| /* |
| * Completely Fair Scheduling (CFS) Class (SCHED_NORMAL/SCHED_BATCH) |
| * |
| * Copyright (C) 2007 Red Hat, Inc., Ingo Molnar <mingo@redhat.com> |
| * |
| * Interactivity improvements by Mike Galbraith |
| * (C) 2007 Mike Galbraith <efault@gmx.de> |
| * |
| * Various enhancements by Dmitry Adamushko. |
| * (C) 2007 Dmitry Adamushko <dmitry.adamushko@gmail.com> |
| * |
| * Group scheduling enhancements by Srivatsa Vaddagiri |
| * Copyright IBM Corporation, 2007 |
| * Author: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com> |
| * |
| * Scaled math optimizations by Thomas Gleixner |
| * Copyright (C) 2007, Thomas Gleixner <tglx@linutronix.de> |
| * |
| * Adaptive scheduling granularity, math enhancements by Peter Zijlstra |
| * Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra |
| */ |
| |
| #include <linux/sched.h> |
| #include <linux/latencytop.h> |
| #include <linux/cpumask.h> |
| #include <linux/cpuidle.h> |
| #include <linux/slab.h> |
| #include <linux/profile.h> |
| #include <linux/interrupt.h> |
| #include <linux/mempolicy.h> |
| #include <linux/migrate.h> |
| #include <linux/task_work.h> |
| #include <linux/module.h> |
| |
| #include "sched.h" |
| #include "tune.h" |
| #include <trace/events/sched.h> |
| |
| /* QHMP/Zone forward declarations */ |
| |
| struct lb_env; |
| struct sd_lb_stats; |
| struct sg_lb_stats; |
| |
| #ifdef CONFIG_SCHED_HMP |
| |
| #ifdef CONFIG_CFS_BANDWIDTH |
| static void inc_cfs_rq_hmp_stats(struct cfs_rq *cfs_rq, |
| struct task_struct *p, int change_cra); |
| static void dec_cfs_rq_hmp_stats(struct cfs_rq *cfs_rq, |
| struct task_struct *p, int change_cra); |
| |
| static inline void dec_throttled_cfs_rq_hmp_stats( |
| struct hmp_sched_stats *stats, |
| struct cfs_rq *cfs_rq); |
| |
| static inline void inc_throttled_cfs_rq_hmp_stats( |
| struct hmp_sched_stats *stats, |
| struct cfs_rq *cfs_rq); |
| |
| static inline void init_cfs_rq_hmp_stats(struct cfs_rq *cfs_rq); |
| |
| #else /* CONFIG_CFS_BANDWIDTH */ |
| static inline void inc_cfs_rq_hmp_stats(struct cfs_rq *cfs_rq, |
| struct task_struct *p, int change_cra) { } |
| static inline void dec_cfs_rq_hmp_stats(struct cfs_rq *cfs_rq, |
| struct task_struct *p, int change_cra) { } |
| #endif /* CONFIG_CFS_BANDWIDTH */ |
| |
| static void fixup_hmp_sched_stats_fair(struct rq *rq, struct task_struct *p, |
| u32 new_task_load, u32 new_pred_demand); |
| #ifdef CONFIG_SMP |
| |
| static struct rq *find_busiest_queue_hmp(struct lb_env *env, |
| struct sched_group *group); |
| static int |
| bail_inter_cluster_balance(struct lb_env *env, struct sd_lb_stats *sds); |
| |
| static bool update_sd_pick_busiest_active_balance(struct lb_env *env, |
| struct sd_lb_stats *sds, |
| struct sched_group *sg, |
| struct sg_lb_stats *sgs); |
| |
| static int select_best_cpu(struct task_struct *p, int target, int reason, |
| int sync); |
| |
| #ifdef CONFIG_NO_HZ_COMMON |
| static int find_new_hmp_ilb(int type); |
| static int _nohz_kick_needed_hmp(struct rq *rq, int cpu, int *type); |
| #endif /* CONFIG_NO_HZ_COMMON */ |
| #endif /* CONFIG_SMP */ |
| #else /* CONFIG_SCHED_HMP */ |
| |
| static inline void inc_cfs_rq_hmp_stats(struct cfs_rq *cfs_rq, |
| struct task_struct *p, int change_cra) { } |
| static inline void dec_cfs_rq_hmp_stats(struct cfs_rq *cfs_rq, |
| struct task_struct *p, int change_cra) { } |
| static inline void dec_throttled_cfs_rq_hmp_stats( |
| struct hmp_sched_stats *stats, |
| struct cfs_rq *cfs_rq) { } |
| static inline void inc_throttled_cfs_rq_hmp_stats( |
| struct hmp_sched_stats *stats, |
| struct cfs_rq *cfs_rq) { } |
| static inline void init_cfs_rq_hmp_stats(struct cfs_rq *cfs_rq) { } |
| |
| #ifdef CONFIG_SMP |
| |
| static inline int |
| bail_inter_cluster_balance(struct lb_env *env, struct sd_lb_stats *sds) |
| { |
| return 0; |
| } |
| |
| static inline bool update_sd_pick_busiest_active_balance(struct lb_env *env, |
| struct sd_lb_stats *sds, |
| struct sched_group *sg, |
| struct sg_lb_stats *sgs) |
| { |
| return false; |
| } |
| #endif /* CONFIG_SMP */ |
| |
| #endif /* CONFIG_SCHED_HMP */ |
| |
| /* |
| * Targeted preemption latency for CPU-bound tasks: |
| * (default: 6ms * (1 + ilog(ncpus)), units: nanoseconds) |
| * |
| * NOTE: this latency value is not the same as the concept of |
| * 'timeslice length' - timeslices in CFS are of variable length |
| * and have no persistent notion like in traditional, time-slice |
| * based scheduling concepts. |
| * |
| * (to see the precise effective timeslice length of your workload, |
| * run vmstat and monitor the context-switches (cs) field) |
| */ |
| unsigned int sysctl_sched_latency = 6000000ULL; |
| unsigned int normalized_sysctl_sched_latency = 6000000ULL; |
| |
| unsigned int sysctl_sched_is_big_little = 0; |
| unsigned int sysctl_sched_sync_hint_enable = 1; |
| unsigned int sysctl_sched_initial_task_util = 0; |
| unsigned int sysctl_sched_cstate_aware = 1; |
| |
| #ifdef CONFIG_SCHED_WALT |
| unsigned int sysctl_sched_use_walt_cpu_util = 1; |
| unsigned int sysctl_sched_use_walt_task_util = 1; |
| __read_mostly unsigned int sysctl_sched_walt_cpu_high_irqload = |
| (10 * NSEC_PER_MSEC); |
| #endif |
| /* |
| * The initial- and re-scaling of tunables is configurable |
| * (default SCHED_TUNABLESCALING_LOG = *(1+ilog(ncpus)) |
| * |
| * Options are: |
| * SCHED_TUNABLESCALING_NONE - unscaled, always *1 |
| * SCHED_TUNABLESCALING_LOG - scaled logarithmical, *1+ilog(ncpus) |
| * SCHED_TUNABLESCALING_LINEAR - scaled linear, *ncpus |
| */ |
| enum sched_tunable_scaling sysctl_sched_tunable_scaling |
| = SCHED_TUNABLESCALING_LOG; |
| |
| /* |
| * Minimal preemption granularity for CPU-bound tasks: |
| * (default: 0.75 msec * (1 + ilog(ncpus)), units: nanoseconds) |
| */ |
| unsigned int sysctl_sched_min_granularity = 750000ULL; |
| unsigned int normalized_sysctl_sched_min_granularity = 750000ULL; |
| |
| /* |
| * is kept at sysctl_sched_latency / sysctl_sched_min_granularity |
| */ |
| static unsigned int sched_nr_latency = 8; |
| |
| /* |
| * After fork, child runs first. If set to 0 (default) then |
| * parent will (try to) run first. |
| */ |
| unsigned int sysctl_sched_child_runs_first __read_mostly; |
| |
| /* |
| * SCHED_OTHER wake-up granularity. |
| * (default: 1 msec * (1 + ilog(ncpus)), units: nanoseconds) |
| * |
| * This option delays the preemption effects of decoupled workloads |
| * and reduces their over-scheduling. Synchronous workloads will still |
| * have immediate wakeup/sleep latencies. |
| */ |
| unsigned int sysctl_sched_wakeup_granularity = 1000000UL; |
| unsigned int normalized_sysctl_sched_wakeup_granularity = 1000000UL; |
| |
| const_debug unsigned int sysctl_sched_migration_cost = 500000UL; |
| |
| /* |
| * The exponential sliding window over which load is averaged for shares |
| * distribution. |
| * (default: 10msec) |
| */ |
| unsigned int __read_mostly sysctl_sched_shares_window = 10000000UL; |
| |
| #ifdef CONFIG_CFS_BANDWIDTH |
| /* |
| * Amount of runtime to allocate from global (tg) to local (per-cfs_rq) pool |
| * each time a cfs_rq requests quota. |
| * |
| * Note: in the case that the slice exceeds the runtime remaining (either due |
| * to consumption or the quota being specified to be smaller than the slice) |
| * we will always only issue the remaining available time. |
| * |
| * default: 5 msec, units: microseconds |
| */ |
| unsigned int sysctl_sched_cfs_bandwidth_slice = 5000UL; |
| #endif |
| |
| /* |
| * The margin used when comparing utilization with CPU capacity: |
| * util * 1024 < capacity * margin |
| */ |
| unsigned int capacity_margin = 1280; /* ~20% */ |
| |
| static inline void update_load_add(struct load_weight *lw, unsigned long inc) |
| { |
| lw->weight += inc; |
| lw->inv_weight = 0; |
| } |
| |
| static inline void update_load_sub(struct load_weight *lw, unsigned long dec) |
| { |
| lw->weight -= dec; |
| lw->inv_weight = 0; |
| } |
| |
| static inline void update_load_set(struct load_weight *lw, unsigned long w) |
| { |
| lw->weight = w; |
| lw->inv_weight = 0; |
| } |
| |
| /* |
| * Increase the granularity value when there are more CPUs, |
| * because with more CPUs the 'effective latency' as visible |
| * to users decreases. But the relationship is not linear, |
| * so pick a second-best guess by going with the log2 of the |
| * number of CPUs. |
| * |
| * This idea comes from the SD scheduler of Con Kolivas: |
| */ |
| static unsigned int get_update_sysctl_factor(void) |
| { |
| unsigned int cpus = min_t(unsigned int, num_online_cpus(), 8); |
| unsigned int factor; |
| |
| switch (sysctl_sched_tunable_scaling) { |
| case SCHED_TUNABLESCALING_NONE: |
| factor = 1; |
| break; |
| case SCHED_TUNABLESCALING_LINEAR: |
| factor = cpus; |
| break; |
| case SCHED_TUNABLESCALING_LOG: |
| default: |
| factor = 1 + ilog2(cpus); |
| break; |
| } |
| |
| return factor; |
| } |
| |
| static void update_sysctl(void) |
| { |
| unsigned int factor = get_update_sysctl_factor(); |
| |
| #define SET_SYSCTL(name) \ |
| (sysctl_##name = (factor) * normalized_sysctl_##name) |
| SET_SYSCTL(sched_min_granularity); |
| SET_SYSCTL(sched_latency); |
| SET_SYSCTL(sched_wakeup_granularity); |
| #undef SET_SYSCTL |
| } |
| |
| void sched_init_granularity(void) |
| { |
| update_sysctl(); |
| } |
| |
| #define WMULT_CONST (~0U) |
| #define WMULT_SHIFT 32 |
| |
| static void __update_inv_weight(struct load_weight *lw) |
| { |
| unsigned long w; |
| |
| if (likely(lw->inv_weight)) |
| return; |
| |
| w = scale_load_down(lw->weight); |
| |
| if (BITS_PER_LONG > 32 && unlikely(w >= WMULT_CONST)) |
| lw->inv_weight = 1; |
| else if (unlikely(!w)) |
| lw->inv_weight = WMULT_CONST; |
| else |
| lw->inv_weight = WMULT_CONST / w; |
| } |
| |
| /* |
| * delta_exec * weight / lw.weight |
| * OR |
| * (delta_exec * (weight * lw->inv_weight)) >> WMULT_SHIFT |
| * |
| * Either weight := NICE_0_LOAD and lw \e sched_prio_to_wmult[], in which case |
| * we're guaranteed shift stays positive because inv_weight is guaranteed to |
| * fit 32 bits, and NICE_0_LOAD gives another 10 bits; therefore shift >= 22. |
| * |
| * Or, weight =< lw.weight (because lw.weight is the runqueue weight), thus |
| * weight/lw.weight <= 1, and therefore our shift will also be positive. |
| */ |
| static u64 __calc_delta(u64 delta_exec, unsigned long weight, struct load_weight *lw) |
| { |
| u64 fact = scale_load_down(weight); |
| int shift = WMULT_SHIFT; |
| |
| __update_inv_weight(lw); |
| |
| if (unlikely(fact >> 32)) { |
| while (fact >> 32) { |
| fact >>= 1; |
| shift--; |
| } |
| } |
| |
| /* hint to use a 32x32->64 mul */ |
| fact = (u64)(u32)fact * lw->inv_weight; |
| |
| while (fact >> 32) { |
| fact >>= 1; |
| shift--; |
| } |
| |
| return mul_u64_u32_shr(delta_exec, fact, shift); |
| } |
| |
| #ifdef CONFIG_SMP |
| static int active_load_balance_cpu_stop(void *data); |
| #endif |
| |
| const struct sched_class fair_sched_class; |
| |
| /************************************************************** |
| * CFS operations on generic schedulable entities: |
| */ |
| |
| #ifdef CONFIG_FAIR_GROUP_SCHED |
| |
| /* cpu runqueue to which this cfs_rq is attached */ |
| static inline struct rq *rq_of(struct cfs_rq *cfs_rq) |
| { |
| return cfs_rq->rq; |
| } |
| |
| /* An entity is a task if it doesn't "own" a runqueue */ |
| #define entity_is_task(se) (!se->my_q) |
| |
| static inline struct task_struct *task_of(struct sched_entity *se) |
| { |
| SCHED_WARN_ON(!entity_is_task(se)); |
| return container_of(se, struct task_struct, se); |
| } |
| |
| /* Walk up scheduling entities hierarchy */ |
| #define for_each_sched_entity(se) \ |
| for (; se; se = se->parent) |
| |
| static inline struct cfs_rq *task_cfs_rq(struct task_struct *p) |
| { |
| return p->se.cfs_rq; |
| } |
| |
| /* runqueue on which this entity is (to be) queued */ |
| static inline struct cfs_rq *cfs_rq_of(struct sched_entity *se) |
| { |
| return se->cfs_rq; |
| } |
| |
| /* runqueue "owned" by this group */ |
| static inline struct cfs_rq *group_cfs_rq(struct sched_entity *grp) |
| { |
| return grp->my_q; |
| } |
| |
| static inline void list_add_leaf_cfs_rq(struct cfs_rq *cfs_rq) |
| { |
| if (!cfs_rq->on_list) { |
| /* |
| * Ensure we either appear before our parent (if already |
| * enqueued) or force our parent to appear after us when it is |
| * enqueued. The fact that we always enqueue bottom-up |
| * reduces this to two cases. |
| */ |
| if (cfs_rq->tg->parent && |
| cfs_rq->tg->parent->cfs_rq[cpu_of(rq_of(cfs_rq))]->on_list) { |
| list_add_rcu(&cfs_rq->leaf_cfs_rq_list, |
| &rq_of(cfs_rq)->leaf_cfs_rq_list); |
| } else { |
| list_add_tail_rcu(&cfs_rq->leaf_cfs_rq_list, |
| &rq_of(cfs_rq)->leaf_cfs_rq_list); |
| } |
| |
| cfs_rq->on_list = 1; |
| } |
| } |
| |
| static inline void list_del_leaf_cfs_rq(struct cfs_rq *cfs_rq) |
| { |
| if (cfs_rq->on_list) { |
| list_del_rcu(&cfs_rq->leaf_cfs_rq_list); |
| cfs_rq->on_list = 0; |
| } |
| } |
| |
| /* Iterate thr' all leaf cfs_rq's on a runqueue */ |
| #define for_each_leaf_cfs_rq(rq, cfs_rq) \ |
| list_for_each_entry_rcu(cfs_rq, &rq->leaf_cfs_rq_list, leaf_cfs_rq_list) |
| |
| /* Do the two (enqueued) entities belong to the same group ? */ |
| static inline struct cfs_rq * |
| is_same_group(struct sched_entity *se, struct sched_entity *pse) |
| { |
| if (se->cfs_rq == pse->cfs_rq) |
| return se->cfs_rq; |
| |
| return NULL; |
| } |
| |
| static inline struct sched_entity *parent_entity(struct sched_entity *se) |
| { |
| return se->parent; |
| } |
| |
| static void |
| find_matching_se(struct sched_entity **se, struct sched_entity **pse) |
| { |
| int se_depth, pse_depth; |
| |
| /* |
| * preemption test can be made between sibling entities who are in the |
| * same cfs_rq i.e who have a common parent. Walk up the hierarchy of |
| * both tasks until we find their ancestors who are siblings of common |
| * parent. |
| */ |
| |
| /* First walk up until both entities are at same depth */ |
| se_depth = (*se)->depth; |
| pse_depth = (*pse)->depth; |
| |
| while (se_depth > pse_depth) { |
| se_depth--; |
| *se = parent_entity(*se); |
| } |
| |
| while (pse_depth > se_depth) { |
| pse_depth--; |
| *pse = parent_entity(*pse); |
| } |
| |
| while (!is_same_group(*se, *pse)) { |
| *se = parent_entity(*se); |
| *pse = parent_entity(*pse); |
| } |
| } |
| |
| #else /* !CONFIG_FAIR_GROUP_SCHED */ |
| |
| static inline struct task_struct *task_of(struct sched_entity *se) |
| { |
| return container_of(se, struct task_struct, se); |
| } |
| |
| static inline struct rq *rq_of(struct cfs_rq *cfs_rq) |
| { |
| return container_of(cfs_rq, struct rq, cfs); |
| } |
| |
| #define entity_is_task(se) 1 |
| |
| #define for_each_sched_entity(se) \ |
| for (; se; se = NULL) |
| |
| static inline struct cfs_rq *task_cfs_rq(struct task_struct *p) |
| { |
| return &task_rq(p)->cfs; |
| } |
| |
| static inline struct cfs_rq *cfs_rq_of(struct sched_entity *se) |
| { |
| struct task_struct *p = task_of(se); |
| struct rq *rq = task_rq(p); |
| |
| return &rq->cfs; |
| } |
| |
| /* runqueue "owned" by this group */ |
| static inline struct cfs_rq *group_cfs_rq(struct sched_entity *grp) |
| { |
| return NULL; |
| } |
| |
| static inline void list_add_leaf_cfs_rq(struct cfs_rq *cfs_rq) |
| { |
| } |
| |
| static inline void list_del_leaf_cfs_rq(struct cfs_rq *cfs_rq) |
| { |
| } |
| |
| #define for_each_leaf_cfs_rq(rq, cfs_rq) \ |
| for (cfs_rq = &rq->cfs; cfs_rq; cfs_rq = NULL) |
| |
| static inline struct sched_entity *parent_entity(struct sched_entity *se) |
| { |
| return NULL; |
| } |
| |
| static inline void |
| find_matching_se(struct sched_entity **se, struct sched_entity **pse) |
| { |
| } |
| |
| #endif /* CONFIG_FAIR_GROUP_SCHED */ |
| |
| static __always_inline |
| void account_cfs_rq_runtime(struct cfs_rq *cfs_rq, u64 delta_exec); |
| |
| /************************************************************** |
| * Scheduling class tree data structure manipulation methods: |
| */ |
| |
| static inline u64 max_vruntime(u64 max_vruntime, u64 vruntime) |
| { |
| s64 delta = (s64)(vruntime - max_vruntime); |
| if (delta > 0) |
| max_vruntime = vruntime; |
| |
| return max_vruntime; |
| } |
| |
| static inline u64 min_vruntime(u64 min_vruntime, u64 vruntime) |
| { |
| s64 delta = (s64)(vruntime - min_vruntime); |
| if (delta < 0) |
| min_vruntime = vruntime; |
| |
| return min_vruntime; |
| } |
| |
| static inline int entity_before(struct sched_entity *a, |
| struct sched_entity *b) |
| { |
| return (s64)(a->vruntime - b->vruntime) < 0; |
| } |
| |
| static void update_min_vruntime(struct cfs_rq *cfs_rq) |
| { |
| struct sched_entity *curr = cfs_rq->curr; |
| |
| u64 vruntime = cfs_rq->min_vruntime; |
| |
| if (curr) { |
| if (curr->on_rq) |
| vruntime = curr->vruntime; |
| else |
| curr = NULL; |
| } |
| |
| if (cfs_rq->rb_leftmost) { |
| struct sched_entity *se = rb_entry(cfs_rq->rb_leftmost, |
| struct sched_entity, |
| run_node); |
| |
| if (!curr) |
| vruntime = se->vruntime; |
| else |
| vruntime = min_vruntime(vruntime, se->vruntime); |
| } |
| |
| /* ensure we never gain time by being placed backwards. */ |
| cfs_rq->min_vruntime = max_vruntime(cfs_rq->min_vruntime, vruntime); |
| #ifndef CONFIG_64BIT |
| smp_wmb(); |
| cfs_rq->min_vruntime_copy = cfs_rq->min_vruntime; |
| #endif |
| } |
| |
| /* |
| * Enqueue an entity into the rb-tree: |
| */ |
| static void __enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se) |
| { |
| struct rb_node **link = &cfs_rq->tasks_timeline.rb_node; |
| struct rb_node *parent = NULL; |
| struct sched_entity *entry; |
| int leftmost = 1; |
| |
| /* |
| * Find the right place in the rbtree: |
| */ |
| while (*link) { |
| parent = *link; |
| entry = rb_entry(parent, struct sched_entity, run_node); |
| /* |
| * We dont care about collisions. Nodes with |
| * the same key stay together. |
| */ |
| if (entity_before(se, entry)) { |
| link = &parent->rb_left; |
| } else { |
| link = &parent->rb_right; |
| leftmost = 0; |
| } |
| } |
| |
| /* |
| * Maintain a cache of leftmost tree entries (it is frequently |
| * used): |
| */ |
| if (leftmost) |
| cfs_rq->rb_leftmost = &se->run_node; |
| |
| rb_link_node(&se->run_node, parent, link); |
| rb_insert_color(&se->run_node, &cfs_rq->tasks_timeline); |
| } |
| |
| static void __dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se) |
| { |
| if (cfs_rq->rb_leftmost == &se->run_node) { |
| struct rb_node *next_node; |
| |
| next_node = rb_next(&se->run_node); |
| cfs_rq->rb_leftmost = next_node; |
| } |
| |
| rb_erase(&se->run_node, &cfs_rq->tasks_timeline); |
| } |
| |
| struct sched_entity *__pick_first_entity(struct cfs_rq *cfs_rq) |
| { |
| struct rb_node *left = cfs_rq->rb_leftmost; |
| |
| if (!left) |
| return NULL; |
| |
| return rb_entry(left, struct sched_entity, run_node); |
| } |
| |
| static struct sched_entity *__pick_next_entity(struct sched_entity *se) |
| { |
| struct rb_node *next = rb_next(&se->run_node); |
| |
| if (!next) |
| return NULL; |
| |
| return rb_entry(next, struct sched_entity, run_node); |
| } |
| |
| #ifdef CONFIG_SCHED_DEBUG |
| struct sched_entity *__pick_last_entity(struct cfs_rq *cfs_rq) |
| { |
| struct rb_node *last = rb_last(&cfs_rq->tasks_timeline); |
| |
| if (!last) |
| return NULL; |
| |
| return rb_entry(last, struct sched_entity, run_node); |
| } |
| |
| /************************************************************** |
| * Scheduling class statistics methods: |
| */ |
| |
| int sched_proc_update_handler(struct ctl_table *table, int write, |
| void __user *buffer, size_t *lenp, |
| loff_t *ppos) |
| { |
| int ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos); |
| unsigned int factor = get_update_sysctl_factor(); |
| |
| if (ret || !write) |
| return ret; |
| |
| sched_nr_latency = DIV_ROUND_UP(sysctl_sched_latency, |
| sysctl_sched_min_granularity); |
| |
| #define WRT_SYSCTL(name) \ |
| (normalized_sysctl_##name = sysctl_##name / (factor)) |
| WRT_SYSCTL(sched_min_granularity); |
| WRT_SYSCTL(sched_latency); |
| WRT_SYSCTL(sched_wakeup_granularity); |
| #undef WRT_SYSCTL |
| |
| return 0; |
| } |
| #endif |
| |
| /* |
| * delta /= w |
| */ |
| static inline u64 calc_delta_fair(u64 delta, struct sched_entity *se) |
| { |
| if (unlikely(se->load.weight != NICE_0_LOAD)) |
| delta = __calc_delta(delta, NICE_0_LOAD, &se->load); |
| |
| return delta; |
| } |
| |
| /* |
| * The idea is to set a period in which each task runs once. |
| * |
| * When there are too many tasks (sched_nr_latency) we have to stretch |
| * this period because otherwise the slices get too small. |
| * |
| * p = (nr <= nl) ? l : l*nr/nl |
| */ |
| static u64 __sched_period(unsigned long nr_running) |
| { |
| if (unlikely(nr_running > sched_nr_latency)) |
| return nr_running * sysctl_sched_min_granularity; |
| else |
| return sysctl_sched_latency; |
| } |
| |
| /* |
| * We calculate the wall-time slice from the period by taking a part |
| * proportional to the weight. |
| * |
| * s = p*P[w/rw] |
| */ |
| static u64 sched_slice(struct cfs_rq *cfs_rq, struct sched_entity *se) |
| { |
| u64 slice = __sched_period(cfs_rq->nr_running + !se->on_rq); |
| |
| for_each_sched_entity(se) { |
| struct load_weight *load; |
| struct load_weight lw; |
| |
| cfs_rq = cfs_rq_of(se); |
| load = &cfs_rq->load; |
| |
| if (unlikely(!se->on_rq)) { |
| lw = cfs_rq->load; |
| |
| update_load_add(&lw, se->load.weight); |
| load = &lw; |
| } |
| slice = __calc_delta(slice, se->load.weight, load); |
| } |
| return slice; |
| } |
| |
| /* |
| * We calculate the vruntime slice of a to-be-inserted task. |
| * |
| * vs = s/w |
| */ |
| static u64 sched_vslice(struct cfs_rq *cfs_rq, struct sched_entity *se) |
| { |
| return calc_delta_fair(sched_slice(cfs_rq, se), se); |
| } |
| |
| #ifdef CONFIG_SMP |
| static int select_idle_sibling(struct task_struct *p, int prev_cpu, int cpu); |
| static unsigned long task_h_load(struct task_struct *p); |
| |
| /* |
| * We choose a half-life close to 1 scheduling period. |
| * Note: The tables runnable_avg_yN_inv and runnable_avg_yN_sum are |
| * dependent on this value. |
| */ |
| #define LOAD_AVG_PERIOD 32 |
| #define LOAD_AVG_MAX 47742 /* maximum possible load avg */ |
| #define LOAD_AVG_MAX_N 345 /* number of full periods to produce LOAD_AVG_MAX */ |
| |
| /* Give new sched_entity start runnable values to heavy its load in infant time */ |
| void init_entity_runnable_average(struct sched_entity *se) |
| { |
| struct sched_avg *sa = &se->avg; |
| |
| sa->last_update_time = 0; |
| /* |
| * sched_avg's period_contrib should be strictly less then 1024, so |
| * we give it 1023 to make sure it is almost a period (1024us), and |
| * will definitely be update (after enqueue). |
| */ |
| sa->period_contrib = 1023; |
| /* |
| * Tasks are intialized with full load to be seen as heavy tasks until |
| * they get a chance to stabilize to their real load level. |
| * Group entities are intialized with zero load to reflect the fact that |
| * nothing has been attached to the task group yet. |
| */ |
| if (entity_is_task(se)) |
| sa->load_avg = scale_load_down(se->load.weight); |
| sa->load_sum = sa->load_avg * LOAD_AVG_MAX; |
| |
| /* |
| * At this point, util_avg won't be used in select_task_rq_fair anyway |
| */ |
| sa->util_avg = sched_freq() ? |
| sysctl_sched_initial_task_util : |
| 0; |
| sa->util_sum = 0; |
| /* when this task enqueue'ed, it will contribute to its cfs_rq's load_avg */ |
| } |
| |
| static inline u64 cfs_rq_clock_task(struct cfs_rq *cfs_rq); |
| static int update_cfs_rq_load_avg(u64 now, struct cfs_rq *cfs_rq, bool update_freq); |
| static void update_tg_load_avg(struct cfs_rq *cfs_rq, int force); |
| static void attach_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se); |
| |
| /* |
| * With new tasks being created, their initial util_avgs are extrapolated |
| * based on the cfs_rq's current util_avg: |
| * |
| * util_avg = cfs_rq->util_avg / (cfs_rq->load_avg + 1) * se.load.weight |
| * |
| * However, in many cases, the above util_avg does not give a desired |
| * value. Moreover, the sum of the util_avgs may be divergent, such |
| * as when the series is a harmonic series. |
| * |
| * To solve this problem, we also cap the util_avg of successive tasks to |
| * only 1/2 of the left utilization budget: |
| * |
| * util_avg_cap = (1024 - cfs_rq->avg.util_avg) / 2^n |
| * |
| * where n denotes the nth task. |
| * |
| * For example, a simplest series from the beginning would be like: |
| * |
| * task util_avg: 512, 256, 128, 64, 32, 16, 8, ... |
| * cfs_rq util_avg: 512, 768, 896, 960, 992, 1008, 1016, ... |
| * |
| * Finally, that extrapolated util_avg is clamped to the cap (util_avg_cap) |
| * if util_avg > util_avg_cap. |
| */ |
| void post_init_entity_util_avg(struct sched_entity *se) |
| { |
| struct cfs_rq *cfs_rq = cfs_rq_of(se); |
| struct sched_avg *sa = &se->avg; |
| long cap = (long)(SCHED_CAPACITY_SCALE - cfs_rq->avg.util_avg) / 2; |
| u64 now = cfs_rq_clock_task(cfs_rq); |
| |
| if (cap > 0) { |
| if (cfs_rq->avg.util_avg != 0) { |
| sa->util_avg = cfs_rq->avg.util_avg * se->load.weight; |
| sa->util_avg /= (cfs_rq->avg.load_avg + 1); |
| |
| if (sa->util_avg > cap) |
| sa->util_avg = cap; |
| } else { |
| sa->util_avg = cap; |
| } |
| sa->util_sum = sa->util_avg * LOAD_AVG_MAX; |
| } |
| |
| if (entity_is_task(se)) { |
| struct task_struct *p = task_of(se); |
| if (p->sched_class != &fair_sched_class) { |
| /* |
| * For !fair tasks do: |
| * |
| update_cfs_rq_load_avg(now, cfs_rq, false); |
| attach_entity_load_avg(cfs_rq, se); |
| switched_from_fair(rq, p); |
| * |
| * such that the next switched_to_fair() has the |
| * expected state. |
| */ |
| se->avg.last_update_time = now; |
| return; |
| } |
| } |
| |
| update_cfs_rq_load_avg(now, cfs_rq, false); |
| attach_entity_load_avg(cfs_rq, se); |
| update_tg_load_avg(cfs_rq, false); |
| } |
| |
| #else /* !CONFIG_SMP */ |
| void init_entity_runnable_average(struct sched_entity *se) |
| { |
| } |
| void post_init_entity_util_avg(struct sched_entity *se) |
| { |
| } |
| static void update_tg_load_avg(struct cfs_rq *cfs_rq, int force) |
| { |
| } |
| #endif /* CONFIG_SMP */ |
| |
| /* |
| * Update the current task's runtime statistics. |
| */ |
| static void update_curr(struct cfs_rq *cfs_rq) |
| { |
| struct sched_entity *curr = cfs_rq->curr; |
| u64 now = rq_clock_task(rq_of(cfs_rq)); |
| u64 delta_exec; |
| |
| if (unlikely(!curr)) |
| return; |
| |
| delta_exec = now - curr->exec_start; |
| if (unlikely((s64)delta_exec <= 0)) |
| return; |
| |
| curr->exec_start = now; |
| |
| schedstat_set(curr->statistics.exec_max, |
| max(delta_exec, curr->statistics.exec_max)); |
| |
| curr->sum_exec_runtime += delta_exec; |
| schedstat_add(cfs_rq->exec_clock, delta_exec); |
| |
| curr->vruntime += calc_delta_fair(delta_exec, curr); |
| update_min_vruntime(cfs_rq); |
| |
| if (entity_is_task(curr)) { |
| struct task_struct *curtask = task_of(curr); |
| |
| trace_sched_stat_runtime(curtask, delta_exec, curr->vruntime); |
| cpuacct_charge(curtask, delta_exec); |
| account_group_exec_runtime(curtask, delta_exec); |
| } |
| |
| account_cfs_rq_runtime(cfs_rq, delta_exec); |
| } |
| |
| static void update_curr_fair(struct rq *rq) |
| { |
| update_curr(cfs_rq_of(&rq->curr->se)); |
| } |
| |
| static inline void |
| update_stats_wait_start(struct cfs_rq *cfs_rq, struct sched_entity *se) |
| { |
| u64 wait_start, prev_wait_start; |
| |
| if (!schedstat_enabled()) |
| return; |
| |
| wait_start = rq_clock(rq_of(cfs_rq)); |
| prev_wait_start = schedstat_val(se->statistics.wait_start); |
| |
| if (entity_is_task(se) && task_on_rq_migrating(task_of(se)) && |
| likely(wait_start > prev_wait_start)) |
| wait_start -= prev_wait_start; |
| |
| schedstat_set(se->statistics.wait_start, wait_start); |
| } |
| |
| static inline void |
| update_stats_wait_end(struct cfs_rq *cfs_rq, struct sched_entity *se) |
| { |
| struct task_struct *p; |
| u64 delta; |
| |
| if (!schedstat_enabled()) |
| return; |
| |
| delta = rq_clock(rq_of(cfs_rq)) - schedstat_val(se->statistics.wait_start); |
| |
| if (entity_is_task(se)) { |
| p = task_of(se); |
| if (task_on_rq_migrating(p)) { |
| /* |
| * Preserve migrating task's wait time so wait_start |
| * time stamp can be adjusted to accumulate wait time |
| * prior to migration. |
| */ |
| schedstat_set(se->statistics.wait_start, delta); |
| return; |
| } |
| trace_sched_stat_wait(p, delta); |
| } |
| |
| schedstat_set(se->statistics.wait_max, |
| max(schedstat_val(se->statistics.wait_max), delta)); |
| schedstat_inc(se->statistics.wait_count); |
| schedstat_add(se->statistics.wait_sum, delta); |
| schedstat_set(se->statistics.wait_start, 0); |
| } |
| |
| static inline void |
| update_stats_enqueue_sleeper(struct cfs_rq *cfs_rq, struct sched_entity *se) |
| { |
| struct task_struct *tsk = NULL; |
| u64 sleep_start, block_start; |
| |
| if (!schedstat_enabled()) |
| return; |
| |
| sleep_start = schedstat_val(se->statistics.sleep_start); |
| block_start = schedstat_val(se->statistics.block_start); |
| |
| if (entity_is_task(se)) |
| tsk = task_of(se); |
| |
| if (sleep_start) { |
| u64 delta = rq_clock(rq_of(cfs_rq)) - sleep_start; |
| |
| if ((s64)delta < 0) |
| delta = 0; |
| |
| if (unlikely(delta > schedstat_val(se->statistics.sleep_max))) |
| schedstat_set(se->statistics.sleep_max, delta); |
| |
| schedstat_set(se->statistics.sleep_start, 0); |
| schedstat_add(se->statistics.sum_sleep_runtime, delta); |
| |
| if (tsk) { |
| account_scheduler_latency(tsk, delta >> 10, 1); |
| trace_sched_stat_sleep(tsk, delta); |
| } |
| } |
| if (block_start) { |
| u64 delta = rq_clock(rq_of(cfs_rq)) - block_start; |
| |
| if ((s64)delta < 0) |
| delta = 0; |
| |
| if (unlikely(delta > schedstat_val(se->statistics.block_max))) |
| schedstat_set(se->statistics.block_max, delta); |
| |
| schedstat_set(se->statistics.block_start, 0); |
| schedstat_add(se->statistics.sum_sleep_runtime, delta); |
| |
| if (tsk) { |
| if (tsk->in_iowait) { |
| schedstat_add(se->statistics.iowait_sum, delta); |
| schedstat_inc(se->statistics.iowait_count); |
| trace_sched_stat_iowait(tsk, delta); |
| } |
| |
| trace_sched_stat_blocked(tsk, delta); |
| trace_sched_blocked_reason(tsk); |
| |
| /* |
| * Blocking time is in units of nanosecs, so shift by |
| * 20 to get a milliseconds-range estimation of the |
| * amount of time that the task spent sleeping: |
| */ |
| if (unlikely(prof_on == SLEEP_PROFILING)) { |
| profile_hits(SLEEP_PROFILING, |
| (void *)get_wchan(tsk), |
| delta >> 20); |
| } |
| account_scheduler_latency(tsk, delta >> 10, 0); |
| } |
| } |
| } |
| |
| /* |
| * Task is being enqueued - update stats: |
| */ |
| static inline void |
| update_stats_enqueue(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags) |
| { |
| if (!schedstat_enabled()) |
| return; |
| |
| /* |
| * Are we enqueueing a waiting task? (for current tasks |
| * a dequeue/enqueue event is a NOP) |
| */ |
| if (se != cfs_rq->curr) |
| update_stats_wait_start(cfs_rq, se); |
| |
| if (flags & ENQUEUE_WAKEUP) |
| update_stats_enqueue_sleeper(cfs_rq, se); |
| } |
| |
| static inline void |
| update_stats_dequeue(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags) |
| { |
| |
| if (!schedstat_enabled()) |
| return; |
| |
| /* |
| * Mark the end of the wait period if dequeueing a |
| * waiting task: |
| */ |
| if (se != cfs_rq->curr) |
| update_stats_wait_end(cfs_rq, se); |
| |
| if ((flags & DEQUEUE_SLEEP) && entity_is_task(se)) { |
| struct task_struct *tsk = task_of(se); |
| |
| if (tsk->state & TASK_INTERRUPTIBLE) |
| schedstat_set(se->statistics.sleep_start, |
| rq_clock(rq_of(cfs_rq))); |
| if (tsk->state & TASK_UNINTERRUPTIBLE) |
| schedstat_set(se->statistics.block_start, |
| rq_clock(rq_of(cfs_rq))); |
| } |
| } |
| |
| /* |
| * We are picking a new current task - update its stats: |
| */ |
| static inline void |
| update_stats_curr_start(struct cfs_rq *cfs_rq, struct sched_entity *se) |
| { |
| /* |
| * We are starting a new run period: |
| */ |
| se->exec_start = rq_clock_task(rq_of(cfs_rq)); |
| } |
| |
| /************************************************** |
| * Scheduling class queueing methods: |
| */ |
| |
| #ifdef CONFIG_NUMA_BALANCING |
| /* |
| * Approximate time to scan a full NUMA task in ms. The task scan period is |
| * calculated based on the tasks virtual memory size and |
| * numa_balancing_scan_size. |
| */ |
| unsigned int sysctl_numa_balancing_scan_period_min = 1000; |
| unsigned int sysctl_numa_balancing_scan_period_max = 60000; |
| |
| /* Portion of address space to scan in MB */ |
| unsigned int sysctl_numa_balancing_scan_size = 256; |
| |
| /* Scan @scan_size MB every @scan_period after an initial @scan_delay in ms */ |
| unsigned int sysctl_numa_balancing_scan_delay = 1000; |
| |
| static unsigned int task_nr_scan_windows(struct task_struct *p) |
| { |
| unsigned long rss = 0; |
| unsigned long nr_scan_pages; |
| |
| /* |
| * Calculations based on RSS as non-present and empty pages are skipped |
| * by the PTE scanner and NUMA hinting faults should be trapped based |
| * on resident pages |
| */ |
| nr_scan_pages = sysctl_numa_balancing_scan_size << (20 - PAGE_SHIFT); |
| rss = get_mm_rss(p->mm); |
| if (!rss) |
| rss = nr_scan_pages; |
| |
| rss = round_up(rss, nr_scan_pages); |
| return rss / nr_scan_pages; |
| } |
| |
| /* For sanitys sake, never scan more PTEs than MAX_SCAN_WINDOW MB/sec. */ |
| #define MAX_SCAN_WINDOW 2560 |
| |
| static unsigned int task_scan_min(struct task_struct *p) |
| { |
| unsigned int scan_size = READ_ONCE(sysctl_numa_balancing_scan_size); |
| unsigned int scan, floor; |
| unsigned int windows = 1; |
| |
| if (scan_size < MAX_SCAN_WINDOW) |
| windows = MAX_SCAN_WINDOW / scan_size; |
| floor = 1000 / windows; |
| |
| scan = sysctl_numa_balancing_scan_period_min / task_nr_scan_windows(p); |
| return max_t(unsigned int, floor, scan); |
| } |
| |
| static unsigned int task_scan_max(struct task_struct *p) |
| { |
| unsigned int smin = task_scan_min(p); |
| unsigned int smax; |
| |
| /* Watch for min being lower than max due to floor calculations */ |
| smax = sysctl_numa_balancing_scan_period_max / task_nr_scan_windows(p); |
| return max(smin, smax); |
| } |
| |
| static void account_numa_enqueue(struct rq *rq, struct task_struct *p) |
| { |
| rq->nr_numa_running += (p->numa_preferred_nid != -1); |
| rq->nr_preferred_running += (p->numa_preferred_nid == task_node(p)); |
| } |
| |
| static void account_numa_dequeue(struct rq *rq, struct task_struct *p) |
| { |
| rq->nr_numa_running -= (p->numa_preferred_nid != -1); |
| rq->nr_preferred_running -= (p->numa_preferred_nid == task_node(p)); |
| } |
| |
| struct numa_group { |
| atomic_t refcount; |
| |
| spinlock_t lock; /* nr_tasks, tasks */ |
| int nr_tasks; |
| pid_t gid; |
| int active_nodes; |
| |
| struct rcu_head rcu; |
| unsigned long total_faults; |
| unsigned long max_faults_cpu; |
| /* |
| * Faults_cpu is used to decide whether memory should move |
| * towards the CPU. As a consequence, these stats are weighted |
| * more by CPU use than by memory faults. |
| */ |
| unsigned long *faults_cpu; |
| unsigned long faults[0]; |
| }; |
| |
| /* Shared or private faults. */ |
| #define NR_NUMA_HINT_FAULT_TYPES 2 |
| |
| /* Memory and CPU locality */ |
| #define NR_NUMA_HINT_FAULT_STATS (NR_NUMA_HINT_FAULT_TYPES * 2) |
| |
| /* Averaged statistics, and temporary buffers. */ |
| #define NR_NUMA_HINT_FAULT_BUCKETS (NR_NUMA_HINT_FAULT_STATS * 2) |
| |
| pid_t task_numa_group_id(struct task_struct *p) |
| { |
| return p->numa_group ? p->numa_group->gid : 0; |
| } |
| |
| /* |
| * The averaged statistics, shared & private, memory & cpu, |
| * occupy the first half of the array. The second half of the |
| * array is for current counters, which are averaged into the |
| * first set by task_numa_placement. |
| */ |
| static inline int task_faults_idx(enum numa_faults_stats s, int nid, int priv) |
| { |
| return NR_NUMA_HINT_FAULT_TYPES * (s * nr_node_ids + nid) + priv; |
| } |
| |
| static inline unsigned long task_faults(struct task_struct *p, int nid) |
| { |
| if (!p->numa_faults) |
| return 0; |
| |
| return p->numa_faults[task_faults_idx(NUMA_MEM, nid, 0)] + |
| p->numa_faults[task_faults_idx(NUMA_MEM, nid, 1)]; |
| } |
| |
| static inline unsigned long group_faults(struct task_struct *p, int nid) |
| { |
| if (!p->numa_group) |
| return 0; |
| |
| return p->numa_group->faults[task_faults_idx(NUMA_MEM, nid, 0)] + |
| p->numa_group->faults[task_faults_idx(NUMA_MEM, nid, 1)]; |
| } |
| |
| static inline unsigned long group_faults_cpu(struct numa_group *group, int nid) |
| { |
| return group->faults_cpu[task_faults_idx(NUMA_MEM, nid, 0)] + |
| group->faults_cpu[task_faults_idx(NUMA_MEM, nid, 1)]; |
| } |
| |
| /* |
| * A node triggering more than 1/3 as many NUMA faults as the maximum is |
| * considered part of a numa group's pseudo-interleaving set. Migrations |
| * between these nodes are slowed down, to allow things to settle down. |
| */ |
| #define ACTIVE_NODE_FRACTION 3 |
| |
| static bool numa_is_active_node(int nid, struct numa_group *ng) |
| { |
| return group_faults_cpu(ng, nid) * ACTIVE_NODE_FRACTION > ng->max_faults_cpu; |
| } |
| |
| /* Handle placement on systems where not all nodes are directly connected. */ |
| static unsigned long score_nearby_nodes(struct task_struct *p, int nid, |
| int maxdist, bool task) |
| { |
| unsigned long score = 0; |
| int node; |
| |
| /* |
| * All nodes are directly connected, and the same distance |
| * from each other. No need for fancy placement algorithms. |
| */ |
| if (sched_numa_topology_type == NUMA_DIRECT) |
| return 0; |
| |
| /* |
| * This code is called for each node, introducing N^2 complexity, |
| * which should be ok given the number of nodes rarely exceeds 8. |
| */ |
| for_each_online_node(node) { |
| unsigned long faults; |
| int dist = node_distance(nid, node); |
| |
| /* |
| * The furthest away nodes in the system are not interesting |
| * for placement; nid was already counted. |
| */ |
| if (dist == sched_max_numa_distance || node == nid) |
| continue; |
| |
| /* |
| * On systems with a backplane NUMA topology, compare groups |
| * of nodes, and move tasks towards the group with the most |
| * memory accesses. When comparing two nodes at distance |
| * "hoplimit", only nodes closer by than "hoplimit" are part |
| * of each group. Skip other nodes. |
| */ |
| if (sched_numa_topology_type == NUMA_BACKPLANE && |
| dist > maxdist) |
| continue; |
| |
| /* Add up the faults from nearby nodes. */ |
| if (task) |
| faults = task_faults(p, node); |
| else |
| faults = group_faults(p, node); |
| |
| /* |
| * On systems with a glueless mesh NUMA topology, there are |
| * no fixed "groups of nodes". Instead, nodes that are not |
| * directly connected bounce traffic through intermediate |
| * nodes; a numa_group can occupy any set of nodes. |
| * The further away a node is, the less the faults count. |
| * This seems to result in good task placement. |
| */ |
| if (sched_numa_topology_type == NUMA_GLUELESS_MESH) { |
| faults *= (sched_max_numa_distance - dist); |
| faults /= (sched_max_numa_distance - LOCAL_DISTANCE); |
| } |
| |
| score += faults; |
| } |
| |
| return score; |
| } |
| |
| /* |
| * These return the fraction of accesses done by a particular task, or |
| * task group, on a particular numa node. The group weight is given a |
| * larger multiplier, in order to group tasks together that are almost |
| * evenly spread out between numa nodes. |
| */ |
| static inline unsigned long task_weight(struct task_struct *p, int nid, |
| int dist) |
| { |
| unsigned long faults, total_faults; |
| |
| if (!p->numa_faults) |
| return 0; |
| |
| total_faults = p->total_numa_faults; |
| |
| if (!total_faults) |
| return 0; |
| |
| faults = task_faults(p, nid); |
| faults += score_nearby_nodes(p, nid, dist, true); |
| |
| return 1000 * faults / total_faults; |
| } |
| |
| static inline unsigned long group_weight(struct task_struct *p, int nid, |
| int dist) |
| { |
| unsigned long faults, total_faults; |
| |
| if (!p->numa_group) |
| return 0; |
| |
| total_faults = p->numa_group->total_faults; |
| |
| if (!total_faults) |
| return 0; |
| |
| faults = group_faults(p, nid); |
| faults += score_nearby_nodes(p, nid, dist, false); |
| |
| return 1000 * faults / total_faults; |
| } |
| |
| bool should_numa_migrate_memory(struct task_struct *p, struct page * page, |
| int src_nid, int dst_cpu) |
| { |
| struct numa_group *ng = p->numa_group; |
| int dst_nid = cpu_to_node(dst_cpu); |
| int last_cpupid, this_cpupid; |
| |
| this_cpupid = cpu_pid_to_cpupid(dst_cpu, current->pid); |
| |
| /* |
| * Multi-stage node selection is used in conjunction with a periodic |
| * migration fault to build a temporal task<->page relation. By using |
| * a two-stage filter we remove short/unlikely relations. |
| * |
| * Using P(p) ~ n_p / n_t as per frequentist probability, we can equate |
| * a task's usage of a particular page (n_p) per total usage of this |
| * page (n_t) (in a given time-span) to a probability. |
| * |
| * Our periodic faults will sample this probability and getting the |
| * same result twice in a row, given these samples are fully |
| * independent, is then given by P(n)^2, provided our sample period |
| * is sufficiently short compared to the usage pattern. |
| * |
| * This quadric squishes small probabilities, making it less likely we |
| * act on an unlikely task<->page relation. |
| */ |
| last_cpupid = page_cpupid_xchg_last(page, this_cpupid); |
| if (!cpupid_pid_unset(last_cpupid) && |
| cpupid_to_nid(last_cpupid) != dst_nid) |
| return false; |
| |
| /* Always allow migrate on private faults */ |
| if (cpupid_match_pid(p, last_cpupid)) |
| return true; |
| |
| /* A shared fault, but p->numa_group has not been set up yet. */ |
| if (!ng) |
| return true; |
| |
| /* |
| * Destination node is much more heavily used than the source |
| * node? Allow migration. |
| */ |
| if (group_faults_cpu(ng, dst_nid) > group_faults_cpu(ng, src_nid) * |
| ACTIVE_NODE_FRACTION) |
| return true; |
| |
| /* |
| * Distribute memory according to CPU & memory use on each node, |
| * with 3/4 hysteresis to avoid unnecessary memory migrations: |
| * |
| * faults_cpu(dst) 3 faults_cpu(src) |
| * --------------- * - > --------------- |
| * faults_mem(dst) 4 faults_mem(src) |
| */ |
| return group_faults_cpu(ng, dst_nid) * group_faults(p, src_nid) * 3 > |
| group_faults_cpu(ng, src_nid) * group_faults(p, dst_nid) * 4; |
| } |
| |
| static unsigned long weighted_cpuload(const int cpu); |
| static unsigned long source_load(int cpu, int type); |
| static unsigned long target_load(int cpu, int type); |
| static unsigned long capacity_of(int cpu); |
| static long effective_load(struct task_group *tg, int cpu, long wl, long wg); |
| |
| /* Cached statistics for all CPUs within a node */ |
| struct numa_stats { |
| unsigned long nr_running; |
| unsigned long load; |
| |
| /* Total compute capacity of CPUs on a node */ |
| unsigned long compute_capacity; |
| |
| /* Approximate capacity in terms of runnable tasks on a node */ |
| unsigned long task_capacity; |
| int has_free_capacity; |
| }; |
| |
| /* |
| * XXX borrowed from update_sg_lb_stats |
| */ |
| static void update_numa_stats(struct numa_stats *ns, int nid) |
| { |
| int smt, cpu, cpus = 0; |
| unsigned long capacity; |
| |
| memset(ns, 0, sizeof(*ns)); |
| for_each_cpu(cpu, cpumask_of_node(nid)) { |
| struct rq *rq = cpu_rq(cpu); |
| |
| ns->nr_running += rq->nr_running; |
| ns->load += weighted_cpuload(cpu); |
| ns->compute_capacity += capacity_of(cpu); |
| |
| cpus++; |
| } |
| |
| /* |
| * If we raced with hotplug and there are no CPUs left in our mask |
| * the @ns structure is NULL'ed and task_numa_compare() will |
| * not find this node attractive. |
| * |
| * We'll either bail at !has_free_capacity, or we'll detect a huge |
| * imbalance and bail there. |
| */ |
| if (!cpus) |
| return; |
| |
| /* smt := ceil(cpus / capacity), assumes: 1 < smt_power < 2 */ |
| smt = DIV_ROUND_UP(SCHED_CAPACITY_SCALE * cpus, ns->compute_capacity); |
| capacity = cpus / smt; /* cores */ |
| |
| ns->task_capacity = min_t(unsigned, capacity, |
| DIV_ROUND_CLOSEST(ns->compute_capacity, SCHED_CAPACITY_SCALE)); |
| ns->has_free_capacity = (ns->nr_running < ns->task_capacity); |
| } |
| |
| struct task_numa_env { |
| struct task_struct *p; |
| |
| int src_cpu, src_nid; |
| int dst_cpu, dst_nid; |
| |
| struct numa_stats src_stats, dst_stats; |
| |
| int imbalance_pct; |
| int dist; |
| |
| struct task_struct *best_task; |
| long best_imp; |
| int best_cpu; |
| }; |
| |
| static void task_numa_assign(struct task_numa_env *env, |
| struct task_struct *p, long imp) |
| { |
| if (env->best_task) |
| put_task_struct(env->best_task); |
| if (p) |
| get_task_struct(p); |
| |
| env->best_task = p; |
| env->best_imp = imp; |
| env->best_cpu = env->dst_cpu; |
| } |
| |
| static bool load_too_imbalanced(long src_load, long dst_load, |
| struct task_numa_env *env) |
| { |
| long imb, old_imb; |
| long orig_src_load, orig_dst_load; |
| long src_capacity, dst_capacity; |
| |
| /* |
| * The load is corrected for the CPU capacity available on each node. |
| * |
| * src_load dst_load |
| * ------------ vs --------- |
| * src_capacity dst_capacity |
| */ |
| src_capacity = env->src_stats.compute_capacity; |
| dst_capacity = env->dst_stats.compute_capacity; |
| |
| /* We care about the slope of the imbalance, not the direction. */ |
| if (dst_load < src_load) |
| swap(dst_load, src_load); |
| |
| /* Is the difference below the threshold? */ |
| imb = dst_load * src_capacity * 100 - |
| src_load * dst_capacity * env->imbalance_pct; |
| if (imb <= 0) |
| return false; |
| |
| /* |
| * The imbalance is above the allowed threshold. |
| * Compare it with the old imbalance. |
| */ |
| orig_src_load = env->src_stats.load; |
| orig_dst_load = env->dst_stats.load; |
| |
| if (orig_dst_load < orig_src_load) |
| swap(orig_dst_load, orig_src_load); |
| |
| old_imb = orig_dst_load * src_capacity * 100 - |
| orig_src_load * dst_capacity * env->imbalance_pct; |
| |
| /* Would this change make things worse? */ |
| return (imb > old_imb); |
| } |
| |
| /* |
| * This checks if the overall compute and NUMA accesses of the system would |
| * be improved if the source tasks was migrated to the target dst_cpu taking |
| * into account that it might be best if task running on the dst_cpu should |
| * be exchanged with the source task |
| */ |
| static void task_numa_compare(struct task_numa_env *env, |
| long taskimp, long groupimp) |
| { |
| struct rq *src_rq = cpu_rq(env->src_cpu); |
| struct rq *dst_rq = cpu_rq(env->dst_cpu); |
| struct task_struct *cur; |
| long src_load, dst_load; |
| long load; |
| long imp = env->p->numa_group ? groupimp : taskimp; |
| long moveimp = imp; |
| int dist = env->dist; |
| |
| rcu_read_lock(); |
| cur = task_rcu_dereference(&dst_rq->curr); |
| if (cur && ((cur->flags & PF_EXITING) || is_idle_task(cur))) |
| cur = NULL; |
| |
| /* |
| * Because we have preemption enabled we can get migrated around and |
| * end try selecting ourselves (current == env->p) as a swap candidate. |
| */ |
| if (cur == env->p) |
| goto unlock; |
| |
| /* |
| * "imp" is the fault differential for the source task between the |
| * source and destination node. Calculate the total differential for |
| * the source task and potential destination task. The more negative |
| * the value is, the more rmeote accesses that would be expected to |
| * be incurred if the tasks were swapped. |
| */ |
| if (cur) { |
| /* Skip this swap candidate if cannot move to the source cpu */ |
| if (!cpumask_test_cpu(env->src_cpu, tsk_cpus_allowed(cur))) |
| goto unlock; |
| |
| /* |
| * If dst and source tasks are in the same NUMA group, or not |
| * in any group then look only at task weights. |
| */ |
| if (cur->numa_group == env->p->numa_group) { |
| imp = taskimp + task_weight(cur, env->src_nid, dist) - |
| task_weight(cur, env->dst_nid, dist); |
| /* |
| * Add some hysteresis to prevent swapping the |
| * tasks within a group over tiny differences. |
| */ |
| if (cur->numa_group) |
| imp -= imp/16; |
| } else { |
| /* |
| * Compare the group weights. If a task is all by |
| * itself (not part of a group), use the task weight |
| * instead. |
| */ |
| if (cur->numa_group) |
| imp += group_weight(cur, env->src_nid, dist) - |
| group_weight(cur, env->dst_nid, dist); |
| else |
| imp += task_weight(cur, env->src_nid, dist) - |
| task_weight(cur, env->dst_nid, dist); |
| } |
| } |
| |
| if (imp <= env->best_imp && moveimp <= env->best_imp) |
| goto unlock; |
| |
| if (!cur) { |
| /* Is there capacity at our destination? */ |
| if (env->src_stats.nr_running <= env->src_stats.task_capacity && |
| !env->dst_stats.has_free_capacity) |
| goto unlock; |
| |
| goto balance; |
| } |
| |
| /* Balance doesn't matter much if we're running a task per cpu */ |
| if (imp > env->best_imp && src_rq->nr_running == 1 && |
| dst_rq->nr_running == 1) |
| goto assign; |
| |
| /* |
| * In the overloaded case, try and keep the load balanced. |
| */ |
| balance: |
| load = task_h_load(env->p); |
| dst_load = env->dst_stats.load + load; |
| src_load = env->src_stats.load - load; |
| |
| if (moveimp > imp && moveimp > env->best_imp) { |
| /* |
| * If the improvement from just moving env->p direction is |
| * better than swapping tasks around, check if a move is |
| * possible. Store a slightly smaller score than moveimp, |
| * so an actually idle CPU will win. |
| */ |
| if (!load_too_imbalanced(src_load, dst_load, env)) { |
| imp = moveimp - 1; |
| cur = NULL; |
| goto assign; |
| } |
| } |
| |
| if (imp <= env->best_imp) |
| goto unlock; |
| |
| if (cur) { |
| load = task_h_load(cur); |
| dst_load -= load; |
| src_load += load; |
| } |
| |
| if (load_too_imbalanced(src_load, dst_load, env)) |
| goto unlock; |
| |
| /* |
| * One idle CPU per node is evaluated for a task numa move. |
| * Call select_idle_sibling to maybe find a better one. |
| */ |
| if (!cur) { |
| /* |
| * select_idle_siblings() uses an per-cpu cpumask that |
| * can be used from IRQ context. |
| */ |
| local_irq_disable(); |
| env->dst_cpu = select_idle_sibling(env->p, env->src_cpu, |
| env->dst_cpu); |
| local_irq_enable(); |
| } |
| |
| assign: |
| task_numa_assign(env, cur, imp); |
| unlock: |
| rcu_read_unlock(); |
| } |
| |
| static void task_numa_find_cpu(struct task_numa_env *env, |
| long taskimp, long groupimp) |
| { |
| int cpu; |
| |
| for_each_cpu(cpu, cpumask_of_node(env->dst_nid)) { |
| /* Skip this CPU if the source task cannot migrate */ |
| if (!cpumask_test_cpu(cpu, tsk_cpus_allowed(env->p))) |
| continue; |
| |
| env->dst_cpu = cpu; |
| task_numa_compare(env, taskimp, groupimp); |
| } |
| } |
| |
| /* Only move tasks to a NUMA node less busy than the current node. */ |
| static bool numa_has_capacity(struct task_numa_env *env) |
| { |
| struct numa_stats *src = &env->src_stats; |
| struct numa_stats *dst = &env->dst_stats; |
| |
| if (src->has_free_capacity && !dst->has_free_capacity) |
| return false; |
| |
| /* |
| * Only consider a task move if the source has a higher load |
| * than the destination, corrected for CPU capacity on each node. |
| * |
| * src->load dst->load |
| * --------------------- vs --------------------- |
| * src->compute_capacity dst->compute_capacity |
| */ |
| if (src->load * dst->compute_capacity * env->imbalance_pct > |
| |
| dst->load * src->compute_capacity * 100) |
| return true; |
| |
| return false; |
| } |
| |
| static int task_numa_migrate(struct task_struct *p) |
| { |
| struct task_numa_env env = { |
| .p = p, |
| |
| .src_cpu = task_cpu(p), |
| .src_nid = task_node(p), |
| |
| .imbalance_pct = 112, |
| |
| .best_task = NULL, |
| .best_imp = 0, |
| .best_cpu = -1, |
| }; |
| struct sched_domain *sd; |
| unsigned long taskweight, groupweight; |
| int nid, ret, dist; |
| long taskimp, groupimp; |
| |
| /* |
| * Pick the lowest SD_NUMA domain, as that would have the smallest |
| * imbalance and would be the first to start moving tasks about. |
| * |
| * And we want to avoid any moving of tasks about, as that would create |
| * random movement of tasks -- counter the numa conditions we're trying |
| * to satisfy here. |
| */ |
| rcu_read_lock(); |
| sd = rcu_dereference(per_cpu(sd_numa, env.src_cpu)); |
| if (sd) |
| env.imbalance_pct = 100 + (sd->imbalance_pct - 100) / 2; |
| rcu_read_unlock(); |
| |
| /* |
| * Cpusets can break the scheduler domain tree into smaller |
| * balance domains, some of which do not cross NUMA boundaries. |
| * Tasks that are "trapped" in such domains cannot be migrated |
| * elsewhere, so there is no point in (re)trying. |
| */ |
| if (unlikely(!sd)) { |
| p->numa_preferred_nid = task_node(p); |
| return -EINVAL; |
| } |
| |
| env.dst_nid = p->numa_preferred_nid; |
| dist = env.dist = node_distance(env.src_nid, env.dst_nid); |
| taskweight = task_weight(p, env.src_nid, dist); |
| groupweight = group_weight(p, env.src_nid, dist); |
| update_numa_stats(&env.src_stats, env.src_nid); |
| taskimp = task_weight(p, env.dst_nid, dist) - taskweight; |
| groupimp = group_weight(p, env.dst_nid, dist) - groupweight; |
| update_numa_stats(&env.dst_stats, env.dst_nid); |
| |
| /* Try to find a spot on the preferred nid. */ |
| if (numa_has_capacity(&env)) |
| task_numa_find_cpu(&env, taskimp, groupimp); |
| |
| /* |
| * Look at other nodes in these cases: |
| * - there is no space available on the preferred_nid |
| * - the task is part of a numa_group that is interleaved across |
| * multiple NUMA nodes; in order to better consolidate the group, |
| * we need to check other locations. |
| */ |
| if (env.best_cpu == -1 || (p->numa_group && p->numa_group->active_nodes > 1)) { |
| for_each_online_node(nid) { |
| if (nid == env.src_nid || nid == p->numa_preferred_nid) |
| continue; |
| |
| dist = node_distance(env.src_nid, env.dst_nid); |
| if (sched_numa_topology_type == NUMA_BACKPLANE && |
| dist != env.dist) { |
| taskweight = task_weight(p, env.src_nid, dist); |
| groupweight = group_weight(p, env.src_nid, dist); |
| } |
| |
| /* Only consider nodes where both task and groups benefit */ |
| taskimp = task_weight(p, nid, dist) - taskweight; |
| groupimp = group_weight(p, nid, dist) - groupweight; |
| if (taskimp < 0 && groupimp < 0) |
| continue; |
| |
| env.dist = dist; |
| env.dst_nid = nid; |
| update_numa_stats(&env.dst_stats, env.dst_nid); |
| if (numa_has_capacity(&env)) |
| task_numa_find_cpu(&env, taskimp, groupimp); |
| } |
| } |
| |
| /* |
| * If the task is part of a workload that spans multiple NUMA nodes, |
| * and is migrating into one of the workload's active nodes, remember |
| * this node as the task's preferred numa node, so the workload can |
| * settle down. |
| * A task that migrated to a second choice node will be better off |
| * trying for a better one later. Do not set the preferred node here. |
| */ |
| if (p->numa_group) { |
| struct numa_group *ng = p->numa_group; |
| |
| if (env.best_cpu == -1) |
| nid = env.src_nid; |
| else |
| nid = env.dst_nid; |
| |
| if (ng->active_nodes > 1 && numa_is_active_node(env.dst_nid, ng)) |
| sched_setnuma(p, env.dst_nid); |
| } |
| |
| /* No better CPU than the current one was found. */ |
| if (env.best_cpu == -1) |
| return -EAGAIN; |
| |
| /* |
| * Reset the scan period if the task is being rescheduled on an |
| * alternative node to recheck if the tasks is now properly placed. |
| */ |
| p->numa_scan_period = task_scan_min(p); |
| |
| if (env.best_task == NULL) { |
| ret = migrate_task_to(p, env.best_cpu); |
| if (ret != 0) |
| trace_sched_stick_numa(p, env.src_cpu, env.best_cpu); |
| return ret; |
| } |
| |
| ret = migrate_swap(p, env.best_task); |
| if (ret != 0) |
| trace_sched_stick_numa(p, env.src_cpu, task_cpu(env.best_task)); |
| put_task_struct(env.best_task); |
| return ret; |
| } |
| |
| /* Attempt to migrate a task to a CPU on the preferred node. */ |
| static void numa_migrate_preferred(struct task_struct *p) |
| { |
| unsigned long interval = HZ; |
| |
| /* This task has no NUMA fault statistics yet */ |
| if (unlikely(p->numa_preferred_nid == -1 || !p->numa_faults)) |
| return; |
| |
| /* Periodically retry migrating the task to the preferred node */ |
| interval = min(interval, msecs_to_jiffies(p->numa_scan_period) / 16); |
| p->numa_migrate_retry = jiffies + interval; |
| |
| /* Success if task is already running on preferred CPU */ |
| if (task_node(p) == p->numa_preferred_nid) |
| return; |
| |
| /* Otherwise, try migrate to a CPU on the preferred node */ |
| task_numa_migrate(p); |
| } |
| |
| /* |
| * Find out how many nodes on the workload is actively running on. Do this by |
| * tracking the nodes from which NUMA hinting faults are triggered. This can |
| * be different from the set of nodes where the workload's memory is currently |
| * located. |
| */ |
| static void numa_group_count_active_nodes(struct numa_group *numa_group) |
| { |
| unsigned long faults, max_faults = 0; |
| int nid, active_nodes = 0; |
| |
| for_each_online_node(nid) { |
| faults = group_faults_cpu(numa_group, nid); |
| if (faults > max_faults) |
| max_faults = faults; |
| } |
| |
| for_each_online_node(nid) { |
| faults = group_faults_cpu(numa_group, nid); |
| if (faults * ACTIVE_NODE_FRACTION > max_faults) |
| active_nodes++; |
| } |
| |
| numa_group->max_faults_cpu = max_faults; |
| numa_group->active_nodes = active_nodes; |
| } |
| |
| /* |
| * When adapting the scan rate, the period is divided into NUMA_PERIOD_SLOTS |
| * increments. The more local the fault statistics are, the higher the scan |
| * period will be for the next scan window. If local/(local+remote) ratio is |
| * below NUMA_PERIOD_THRESHOLD (where range of ratio is 1..NUMA_PERIOD_SLOTS) |
| * the scan period will decrease. Aim for 70% local accesses. |
| */ |
| #define NUMA_PERIOD_SLOTS 10 |
| #define NUMA_PERIOD_THRESHOLD 7 |
| |
| /* |
| * Increase the scan period (slow down scanning) if the majority of |
| * our memory is already on our local node, or if the majority of |
| * the page accesses are shared with other processes. |
| * Otherwise, decrease the scan period. |
| */ |
| static void update_task_scan_period(struct task_struct *p, |
| unsigned long shared, unsigned long private) |
| { |
| unsigned int period_slot; |
| int ratio; |
| int diff; |
| |
| unsigned long remote = p->numa_faults_locality[0]; |
| unsigned long local = p->numa_faults_locality[1]; |
| |
| /* |
| * If there were no record hinting faults then either the task is |
| * completely idle or all activity is areas that are not of interest |
| * to automatic numa balancing. Related to that, if there were failed |
| * migration then it implies we are migrating too quickly or the local |
| * node is overloaded. In either case, scan slower |
| */ |
| if (local + shared == 0 || p->numa_faults_locality[2]) { |
| p->numa_scan_period = min(p->numa_scan_period_max, |
| p->numa_scan_period << 1); |
| |
| p->mm->numa_next_scan = jiffies + |
| msecs_to_jiffies(p->numa_scan_period); |
| |
| return; |
| } |
| |
| /* |
| * Prepare to scale scan period relative to the current period. |
| * == NUMA_PERIOD_THRESHOLD scan period stays the same |
| * < NUMA_PERIOD_THRESHOLD scan period decreases (scan faster) |
| * >= NUMA_PERIOD_THRESHOLD scan period increases (scan slower) |
| */ |
| period_slot = DIV_ROUND_UP(p->numa_scan_period, NUMA_PERIOD_SLOTS); |
| ratio = (local * NUMA_PERIOD_SLOTS) / (local + remote); |
| if (ratio >= NUMA_PERIOD_THRESHOLD) { |
| int slot = ratio - NUMA_PERIOD_THRESHOLD; |
| if (!slot) |
| slot = 1; |
| diff = slot * period_slot; |
| } else { |
| diff = -(NUMA_PERIOD_THRESHOLD - ratio) * period_slot; |
| |
| /* |
| * Scale scan rate increases based on sharing. There is an |
| * inverse relationship between the degree of sharing and |
| * the adjustment made to the scanning period. Broadly |
| * speaking the intent is that there is little point |
| * scanning faster if shared accesses dominate as it may |
| * simply bounce migrations uselessly |
| */ |
| ratio = DIV_ROUND_UP(private * NUMA_PERIOD_SLOTS, (private + shared + 1)); |
| diff = (diff * ratio) / NUMA_PERIOD_SLOTS; |
| } |
| |
| p->numa_scan_period = clamp(p->numa_scan_period + diff, |
| task_scan_min(p), task_scan_max(p)); |
| memset(p->numa_faults_locality, 0, sizeof(p->numa_faults_locality)); |
| } |
| |
| /* |
| * Get the fraction of time the task has been running since the last |
| * NUMA placement cycle. The scheduler keeps similar statistics, but |
| * decays those on a 32ms period, which is orders of magnitude off |
| * from the dozens-of-seconds NUMA balancing period. Use the scheduler |
| * stats only if the task is so new there are no NUMA statistics yet. |
| */ |
| static u64 numa_get_avg_runtime(struct task_struct *p, u64 *period) |
| { |
| u64 runtime, delta, now; |
| /* Use the start of this time slice to avoid calculations. */ |
| now = p->se.exec_start; |
| runtime = p->se.sum_exec_runtime; |
| |
| if (p->last_task_numa_placement) { |
| delta = runtime - p->last_sum_exec_runtime; |
| *period = now - p->last_task_numa_placement; |
| } else { |
| delta = p->se.avg.load_sum / p->se.load.weight; |
| *period = LOAD_AVG_MAX; |
| } |
| |
| p->last_sum_exec_runtime = runtime; |
| p->last_task_numa_placement = now; |
| |
| return delta; |
| } |
| |
| /* |
| * Determine the preferred nid for a task in a numa_group. This needs to |
| * be done in a way that produces consistent results with group_weight, |
| * otherwise workloads might not converge. |
| */ |
| static int preferred_group_nid(struct task_struct *p, int nid) |
| { |
| nodemask_t nodes; |
| int dist; |
| |
| /* Direct connections between all NUMA nodes. */ |
| if (sched_numa_topology_type == NUMA_DIRECT) |
| return nid; |
| |
| /* |
| * On a system with glueless mesh NUMA topology, group_weight |
| * scores nodes according to the number of NUMA hinting faults on |
| * both the node itself, and on nearby nodes. |
| */ |
| if (sched_numa_topology_type == NUMA_GLUELESS_MESH) { |
| unsigned long score, max_score = 0; |
| int node, max_node = nid; |
| |
| dist = sched_max_numa_distance; |
| |
| for_each_online_node(node) { |
| score = group_weight(p, node, dist); |
| if (score > max_score) { |
| max_score = score; |
| max_node = node; |
| } |
| } |
| return max_node; |
| } |
| |
| /* |
| * Finding the preferred nid in a system with NUMA backplane |
| * interconnect topology is more involved. The goal is to locate |
| * tasks from numa_groups near each other in the system, and |
| * untangle workloads from different sides of the system. This requires |
| * searching down the hierarchy of node groups, recursively searching |
| * inside the highest scoring group of nodes. The nodemask tricks |
| * keep the complexity of the search down. |
| */ |
| nodes = node_online_map; |
| for (dist = sched_max_numa_distance; dist > LOCAL_DISTANCE; dist--) { |
| unsigned long max_faults = 0; |
| nodemask_t max_group = NODE_MASK_NONE; |
| int a, b; |
| |
| /* Are there nodes at this distance from each other? */ |
| if (!find_numa_distance(dist)) |
| continue; |
| |
| for_each_node_mask(a, nodes) { |
| unsigned long faults = 0; |
| nodemask_t this_group; |
| nodes_clear(this_group); |
| |
| /* Sum group's NUMA faults; includes a==b case. */ |
| for_each_node_mask(b, nodes) { |
| if (node_distance(a, b) < dist) { |
| faults += group_faults(p, b); |
| node_set(b, this_group); |
| node_clear(b, nodes); |
| } |
| } |
| |
| /* Remember the top group. */ |
| if (faults > max_faults) { |
| max_faults = faults; |
| max_group = this_group; |
| /* |
| * subtle: at the smallest distance there is |
| * just one node left in each "group", the |
| * winner is the preferred nid. |
| */ |
| nid = a; |
| } |
| } |
| /* Next round, evaluate the nodes within max_group. */ |
| if (!max_faults) |
| break; |
| nodes = max_group; |
| } |
| return nid; |
| } |
| |
| static void task_numa_placement(struct task_struct *p) |
| { |
| int seq, nid, max_nid = -1, max_group_nid = -1; |
| unsigned long max_faults = 0, max_group_faults = 0; |
| unsigned long fault_types[2] = { 0, 0 }; |
| unsigned long total_faults; |
| u64 runtime, period; |
| spinlock_t *group_lock = NULL; |
| |
| /* |
| * The p->mm->numa_scan_seq field gets updated without |
| * exclusive access. Use READ_ONCE() here to ensure |
| * that the field is read in a single access: |
| */ |
| seq = READ_ONCE(p->mm->numa_scan_seq); |
| if (p->numa_scan_seq == seq) |
| return; |
| p->numa_scan_seq = seq; |
| p->numa_scan_period_max = task_scan_max(p); |
| |
| total_faults = p->numa_faults_locality[0] + |
| p->numa_faults_locality[1]; |
| runtime = numa_get_avg_runtime(p, &period); |
| |
| /* If the task is part of a group prevent parallel updates to group stats */ |
| if (p->numa_group) { |
| group_lock = &p->numa_group->lock; |
| spin_lock_irq(group_lock); |
| } |
| |
| /* Find the node with the highest number of faults */ |
| for_each_online_node(nid) { |
| /* Keep track of the offsets in numa_faults array */ |
| int mem_idx, membuf_idx, cpu_idx, cpubuf_idx; |
| unsigned long faults = 0, group_faults = 0; |
| int priv; |
| |
| for (priv = 0; priv < NR_NUMA_HINT_FAULT_TYPES; priv++) { |
| long diff, f_diff, f_weight; |
| |
| mem_idx = task_faults_idx(NUMA_MEM, nid, priv); |
| membuf_idx = task_faults_idx(NUMA_MEMBUF, nid, priv); |
| cpu_idx = task_faults_idx(NUMA_CPU, nid, priv); |
| cpubuf_idx = task_faults_idx(NUMA_CPUBUF, nid, priv); |
| |
| /* Decay existing window, copy faults since last scan */ |
| diff = p->numa_faults[membuf_idx] - p->numa_faults[mem_idx] / 2; |
| fault_types[priv] += p->numa_faults[membuf_idx]; |
| p->numa_faults[membuf_idx] = 0; |
| |
| /* |
| * Normalize the faults_from, so all tasks in a group |
| * count according to CPU use, instead of by the raw |
| * number of faults. Tasks with little runtime have |
| * little over-all impact on throughput, and thus their |
| * faults are less important. |
| */ |
| f_weight = div64_u64(runtime << 16, period + 1); |
| f_weight = (f_weight * p->numa_faults[cpubuf_idx]) / |
| (total_faults + 1); |
| f_diff = f_weight - p->numa_faults[cpu_idx] / 2; |
| p->numa_faults[cpubuf_idx] = 0; |
| |
| p->numa_faults[mem_idx] += diff; |
| p->numa_faults[cpu_idx] += f_diff; |
| faults += p->numa_faults[mem_idx]; |
| p->total_numa_faults += diff; |
| if (p->numa_group) { |
| /* |
| * safe because we can only change our own group |
| * |
| * mem_idx represents the offset for a given |
| * nid and priv in a specific region because it |
| * is at the beginning of the numa_faults array. |
| */ |
| p->numa_group->faults[mem_idx] += diff; |
| p->numa_group->faults_cpu[mem_idx] += f_diff; |
| p->numa_group->total_faults += diff; |
| group_faults += p->numa_group->faults[mem_idx]; |
| } |
| } |
| |
| if (faults > max_faults) { |
| max_faults = faults; |
| max_nid = nid; |
| } |
| |
| if (group_faults > max_group_faults) { |
| max_group_faults = group_faults; |
| max_group_nid = nid; |
| } |
| } |
| |
| update_task_scan_period(p, fault_types[0], fault_types[1]); |
| |
| if (p->numa_group) { |
| numa_group_count_active_nodes(p->numa_group); |
| spin_unlock_irq(group_lock); |
| max_nid = preferred_group_nid(p, max_group_nid); |
| } |
| |
| if (max_faults) { |
| /* Set the new preferred node */ |
| if (max_nid != p->numa_preferred_nid) |
| sched_setnuma(p, max_nid); |
| |
| if (task_node(p) != p->numa_preferred_nid) |
| numa_migrate_preferred(p); |
| } |
| } |
| |
| static inline int get_numa_group(struct numa_group *grp) |
| { |
| return atomic_inc_not_zero(&grp->refcount); |
| } |
| |
| static inline void put_numa_group(struct numa_group *grp) |
| { |
| if (atomic_dec_and_test(&grp->refcount)) |
| kfree_rcu(grp, rcu); |
| } |
| |
| static void task_numa_group(struct task_struct *p, int cpupid, int flags, |
| int *priv) |
| { |
| struct numa_group *grp, *my_grp; |
| struct task_struct *tsk; |
| bool join = false; |
| int cpu = cpupid_to_cpu(cpupid); |
| int i; |
| |
| if (unlikely(!p->numa_group)) { |
| unsigned int size = sizeof(struct numa_group) + |
| 4*nr_node_ids*sizeof(unsigned long); |
| |
| grp = kzalloc(size, GFP_KERNEL | __GFP_NOWARN); |
| if (!grp) |
| return; |
| |
| atomic_set(&grp->refcount, 1); |
| grp->active_nodes = 1; |
| grp->max_faults_cpu = 0; |
| spin_lock_init(&grp->lock); |
| grp->gid = p->pid; |
| /* Second half of the array tracks nids where faults happen */ |
| grp->faults_cpu = grp->faults + NR_NUMA_HINT_FAULT_TYPES * |
| nr_node_ids; |
| |
| for (i = 0; i < NR_NUMA_HINT_FAULT_STATS * nr_node_ids; i++) |
| grp->faults[i] = p->numa_faults[i]; |
| |
| grp->total_faults = p->total_numa_faults; |
| |
| grp->nr_tasks++; |
| rcu_assign_pointer(p->numa_group, grp); |
| } |
| |
| rcu_read_lock(); |
| tsk = READ_ONCE(cpu_rq(cpu)->curr); |
| |
| if (!cpupid_match_pid(tsk, cpupid)) |
| goto no_join; |
| |
| grp = rcu_dereference(tsk->numa_group); |
| if (!grp) |
| goto no_join; |
| |
| my_grp = p->numa_group; |
| if (grp == my_grp) |
| goto no_join; |
| |
| /* |
| * Only join the other group if its bigger; if we're the bigger group, |
| * the other task will join us. |
| */ |
| if (my_grp->nr_tasks > grp->nr_tasks) |
| goto no_join; |
| |
| /* |
| * Tie-break on the grp address. |
| */ |
| if (my_grp->nr_tasks == grp->nr_tasks && my_grp > grp) |
| goto no_join; |
| |
| /* Always join threads in the same process. */ |
| if (tsk->mm == current->mm) |
| join = true; |
| |
| /* Simple filter to avoid false positives due to PID collisions */ |
| if (flags & TNF_SHARED) |
| join = true; |
| |
| /* Update priv based on whether false sharing was detected */ |
| *priv = !join; |
| |
| if (join && !get_numa_group(grp)) |
| goto no_join; |
| |
| rcu_read_unlock(); |
| |
| if (!join) |
| return; |
| |
| BUG_ON(irqs_disabled()); |
| double_lock_irq(&my_grp->lock, &grp->lock); |
| |
| for (i = 0; i < NR_NUMA_HINT_FAULT_STATS * nr_node_ids; i++) { |
| my_grp->faults[i] -= p->numa_faults[i]; |
| grp->faults[i] += p->numa_faults[i]; |
| } |
| my_grp->total_faults -= p->total_numa_faults; |
| grp->total_faults += p->total_numa_faults; |
| |
| my_grp->nr_tasks--; |
| grp->nr_tasks++; |
| |
| spin_unlock(&my_grp->lock); |
| spin_unlock_irq(&grp->lock); |
| |
| rcu_assign_pointer(p->numa_group, grp); |
| |
| put_numa_group(my_grp); |
| return; |
| |
| no_join: |
| rcu_read_unlock(); |
| return; |
| } |
| |
| void task_numa_free(struct task_struct *p) |
| { |
| struct numa_group *grp = p->numa_group; |
| void *numa_faults = p->numa_faults; |
| unsigned long flags; |
| int i; |
| |
| if (grp) { |
| spin_lock_irqsave(&grp->lock, flags); |
| for (i = 0; i < NR_NUMA_HINT_FAULT_STATS * nr_node_ids; i++) |
| grp->faults[i] -= p->numa_faults[i]; |
| grp->total_faults -= p->total_numa_faults; |
| |
| grp->nr_tasks--; |
| spin_unlock_irqrestore(&grp->lock, flags); |
| RCU_INIT_POINTER(p->numa_group, NULL); |
| put_numa_group(grp); |
| } |
| |
| p->numa_faults = NULL; |
| kfree(numa_faults); |
| } |
| |
| /* |
| * Got a PROT_NONE fault for a page on @node. |
| */ |
| void task_numa_fault(int last_cpupid, int mem_node, int pages, int flags) |
| { |
| struct task_struct *p = current; |
| bool migrated = flags & TNF_MIGRATED; |
| int cpu_node = task_node(current); |
| int local = !!(flags & TNF_FAULT_LOCAL); |
| struct numa_group *ng; |
| int priv; |
| |
| if (!static_branch_likely(&sched_numa_balancing)) |
| return; |
| |
| /* for example, ksmd faulting in a user's mm */ |
| if (!p->mm) |
| return; |
| |
| /* Allocate buffer to track faults on a per-node basis */ |
| if (unlikely(!p->numa_faults)) { |
| int size = sizeof(*p->numa_faults) * |
| NR_NUMA_HINT_FAULT_BUCKETS * nr_node_ids; |
| |
| p->numa_faults = kzalloc(size, GFP_KERNEL|__GFP_NOWARN); |
| if (!p->numa_faults) |
| return; |
| |
| p->total_numa_faults = 0; |
| memset(p->numa_faults_locality, 0, sizeof(p->numa_faults_locality)); |
| } |
| |
| /* |
| * First accesses are treated as private, otherwise consider accesses |
| * to be private if the accessing pid has not changed |
| */ |
| if (unlikely(last_cpupid == (-1 & LAST_CPUPID_MASK))) { |
| priv = 1; |
| } else { |
| priv = cpupid_match_pid(p, last_cpupid); |
| if (!priv && !(flags & TNF_NO_GROUP)) |
| task_numa_group(p, last_cpupid, flags, &priv); |
| } |
| |
| /* |
| * If a workload spans multiple NUMA nodes, a shared fault that |
| * occurs wholly within the set of nodes that the workload is |
| * actively using should be counted as local. This allows the |
| * scan rate to slow down when a workload has settled down. |
| */ |
| ng = p->numa_group; |
| if (!priv && !local && ng && ng->active_nodes > 1 && |
| numa_is_active_node(cpu_node, ng) && |
| numa_is_active_node(mem_node, ng)) |
| local = 1; |
| |
| task_numa_placement(p); |
| |
| /* |
| * Retry task to preferred node migration periodically, in case it |
| * case it previously failed, or the scheduler moved us. |
| */ |
| if (time_after(jiffies, p->numa_migrate_retry)) |
| numa_migrate_preferred(p); |
| |
| if (migrated) |
| p->numa_pages_migrated += pages; |
| if (flags & TNF_MIGRATE_FAIL) |
| p->numa_faults_locality[2] += pages; |
| |
| p->numa_faults[task_faults_idx(NUMA_MEMBUF, mem_node, priv)] += pages; |
| p->numa_faults[task_faults_idx(NUMA_CPUBUF, cpu_node, priv)] += pages; |
| p->numa_faults_locality[local] += pages; |
| } |
| |
| static void reset_ptenuma_scan(struct task_struct *p) |
| { |
| /* |
| * We only did a read acquisition of the mmap sem, so |
| * p->mm->numa_scan_seq is written to without exclusive access |
| * and the update is not guaranteed to be atomic. That's not |
| * much of an issue though, since this is just used for |
| * statistical sampling. Use READ_ONCE/WRITE_ONCE, which are not |
| * expensive, to avoid any form of compiler optimizations: |
| */ |
| WRITE_ONCE(p->mm->numa_scan_seq, READ_ONCE(p->mm->numa_scan_seq) + 1); |
| p->mm->numa_scan_offset = 0; |
| } |
| |
| /* |
| * The expensive part of numa migration is done from task_work context. |
| * Triggered from task_tick_numa(). |
| */ |
| void task_numa_work(struct callback_head *work) |
| { |
| unsigned long migrate, next_scan, now = jiffies; |
| struct task_struct *p = current; |
| struct mm_struct *mm = p->mm; |
| u64 runtime = p->se.sum_exec_runtime; |
| struct vm_area_struct *vma; |
| unsigned long start, end; |
| unsigned long nr_pte_updates = 0; |
| long pages, virtpages; |
| |
| SCHED_WARN_ON(p != container_of(work, struct task_struct, numa_work)); |
| |
| work->next = work; /* protect against double add */ |
| /* |
| * Who cares about NUMA placement when they're dying. |
| * |
| * NOTE: make sure not to dereference p->mm before this check, |
| * exit_task_work() happens _after_ exit_mm() so we could be called |
| * without p->mm even though we still had it when we enqueued this |
| * work. |
| */ |
| if (p->flags & PF_EXITING) |
| return; |
| |
| if (!mm->numa_next_scan) { |
| mm->numa_next_scan = now + |
| msecs_to_jiffies(sysctl_numa_balancing_scan_delay); |
| } |
| |
| /* |
| * Enforce maximal scan/migration frequency.. |
| */ |
| migrate = mm->numa_next_scan; |
| if (time_before(now, migrate)) |
| return; |
| |
| if (p->numa_scan_period == 0) { |
| p->numa_scan_period_max = task_scan_max(p); |
| p->numa_scan_period = task_scan_min(p); |
| } |
| |
| next_scan = now + msecs_to_jiffies(p->numa_scan_period); |
| if (cmpxchg(&mm->numa_next_scan, migrate, next_scan) != migrate) |
| return; |
| |
| /* |
| * Delay this task enough that another task of this mm will likely win |
| * the next time around. |
| */ |
| p->node_stamp += 2 * TICK_NSEC; |
| |
| start = mm->numa_scan_offset; |
| pages = sysctl_numa_balancing_scan_size; |
| pages <<= 20 - PAGE_SHIFT; /* MB in pages */ |
| virtpages = pages * 8; /* Scan up to this much virtual space */ |
| if (!pages) |
| return; |
| |
| |
| down_read(&mm->mmap_sem); |
| vma = find_vma(mm, start); |
| if (!vma) { |
| reset_ptenuma_scan(p); |
| start = 0; |
| vma = mm->mmap; |
| } |
| for (; vma; vma = vma->vm_next) { |
| if (!vma_migratable(vma) || !vma_policy_mof(vma) || |
| is_vm_hugetlb_page(vma) || (vma->vm_flags & VM_MIXEDMAP)) { |
| continue; |
| } |
| |
| /* |
| * Shared library pages mapped by multiple processes are not |
| * migrated as it is expected they are cache replicated. Avoid |
| * hinting faults in read-only file-backed mappings or the vdso |
| * as migrating the pages will be of marginal benefit. |
| */ |
| if (!vma->vm_mm || |
| (vma->vm_file && (vma->vm_flags & (VM_READ|VM_WRITE)) == (VM_READ))) |
| continue; |
| |
| /* |
| * Skip inaccessible VMAs to avoid any confusion between |
| * PROT_NONE and NUMA hinting ptes |
| */ |
| if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE))) |
| continue; |
| |
| do { |
| start = max(start, vma->vm_start); |
| end = ALIGN(start + (pages << PAGE_SHIFT), HPAGE_SIZE); |
| end = min(end, vma->vm_end); |
| nr_pte_updates = change_prot_numa(vma, start, end); |
| |
| /* |
| * Try to scan sysctl_numa_balancing_size worth of |
| * hpages that have at least one present PTE that |
| * is not already pte-numa. If the VMA contains |
| * areas that are unused or already full of prot_numa |
| * PTEs, scan up to virtpages, to skip through those |
| * areas faster. |
| */ |
| if (nr_pte_updates) |
| pages -= (end - start) >> PAGE_SHIFT; |
| virtpages -= (end - start) >> PAGE_SHIFT; |
| |
| start = end; |
| if (pages <= 0 || virtpages <= 0) |
| goto out; |
| |
| cond_resched(); |
| } while (end != vma->vm_end); |
| } |
| |
| out: |
| /* |
| * It is possible to reach the end of the VMA list but the last few |
| * VMAs are not guaranteed to the vma_migratable. If they are not, we |
| * would find the !migratable VMA on the next scan but not reset the |
| * scanner to the start so check it now. |
| */ |
| if (vma) |
| mm->numa_scan_offset = start; |
| else |
| reset_ptenuma_scan(p); |
| up_read(&mm->mmap_sem); |
| |
| /* |
| * Make sure tasks use at least 32x as much time to run other code |
| * than they used here, to limit NUMA PTE scanning overhead to 3% max. |
| * Usually update_task_scan_period slows down scanning enough; on an |
| * overloaded system we need to limit overhead on a per task basis. |
| */ |
| if (unlikely(p->se.sum_exec_runtime != runtime)) { |
| u64 diff = p->se.sum_exec_runtime - runtime; |
| p->node_stamp += 32 * diff; |
| } |
| } |
| |
| /* |
| * Drive the periodic memory faults.. |
| */ |
| void task_tick_numa(struct rq *rq, struct task_struct *curr) |
| { |
| struct callback_head *work = &curr->numa_work; |
| u64 period, now; |
| |
| /* |
| * We don't care about NUMA placement if we don't have memory. |
| */ |
| if (!curr->mm || (curr->flags & PF_EXITING) || work->next != work) |
| return; |
| |
| /* |
| * Using runtime rather than walltime has the dual advantage that |
| * we (mostly) drive the selection from busy threads and that the |
| * task needs to have done some actual work before we bother with |
| * NUMA placement. |
| */ |
| now = curr->se.sum_exec_runtime; |
| period = (u64)curr->numa_scan_period * NSEC_PER_MSEC; |
| |
| if (now > curr->node_stamp + period) { |
| if (!curr->node_stamp) |
| curr->numa_scan_period = task_scan_min(curr); |
| curr->node_stamp += period; |
| |
| if (!time_before(jiffies, curr->mm->numa_next_scan)) { |
| init_task_work(work, task_numa_work); /* TODO: move this into sched_fork() */ |
| task_work_add(curr, work, true); |
| } |
| } |
| } |
| #else |
| static void task_tick_numa(struct rq *rq, struct task_struct *curr) |
| { |
| } |
| |
| static inline void account_numa_enqueue(struct rq *rq, struct task_struct *p) |
| { |
| } |
| |
| static inline void account_numa_dequeue(struct rq *rq, struct task_struct *p) |
| { |
| } |
| #endif /* CONFIG_NUMA_BALANCING */ |
| |
| static void |
| account_entity_enqueue(struct cfs_rq *cfs_rq, struct sched_entity *se) |
| { |
| update_load_add(&cfs_rq->load, se->load.weight); |
| if (!parent_entity(se)) |
| update_load_add(&rq_of(cfs_rq)->load, se->load.weight); |
| #ifdef CONFIG_SMP |
| if (entity_is_task(se)) { |
| struct rq *rq = rq_of(cfs_rq); |
| |
| account_numa_enqueue(rq, task_of(se)); |
| list_add(&se->group_node, &rq->cfs_tasks); |
| } |
| #endif |
| cfs_rq->nr_running++; |
| } |
| |
| static void |
| account_entity_dequeue(struct cfs_rq *cfs_rq, struct sched_entity *se) |
| { |
| update_load_sub(&cfs_rq->load, se->load.weight); |
| if (!parent_entity(se)) |
| update_load_sub(&rq_of(cfs_rq)->load, se->load.weight); |
| #ifdef CONFIG_SMP |
| if (entity_is_task(se)) { |
| account_numa_dequeue(rq_of(cfs_rq), task_of(se)); |
| list_del_init(&se->group_node); |
| } |
| #endif |
| cfs_rq->nr_running--; |
| } |
| |
| #ifdef CONFIG_FAIR_GROUP_SCHED |
| # ifdef CONFIG_SMP |
| static long calc_cfs_shares(struct cfs_rq *cfs_rq, struct task_group *tg) |
| { |
| long tg_weight, load, shares; |
| |
| /* |
| * This really should be: cfs_rq->avg.load_avg, but instead we use |
| * cfs_rq->load.weight, which is its upper bound. This helps ramp up |
| * the shares for small weight interactive tasks. |
| */ |
| load = scale_load_down(cfs_rq->load.weight); |
| |
| tg_weight = atomic_long_read(&tg->load_avg); |
| |
| /* Ensure tg_weight >= load */ |
| tg_weight -= cfs_rq->tg_load_avg_contrib; |
| tg_weight += load; |
| |
| shares = (tg->shares * load); |
| if (tg_weight) |
| shares /= tg_weight; |
| |
| if (shares < MIN_SHARES) |
| shares = MIN_SHARES; |
| if (shares > tg->shares) |
| shares = tg->shares; |
| |
| return shares; |
| } |
| # else /* CONFIG_SMP */ |
| static inline long calc_cfs_shares(struct cfs_rq *cfs_rq, struct task_group *tg) |
| { |
| return tg->shares; |
| } |
| # endif /* CONFIG_SMP */ |
| |
| static void reweight_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, |
| unsigned long weight) |
| { |
| if (se->on_rq) { |
| /* commit outstanding execution time */ |
| if (cfs_rq->curr == se) |
| update_curr(cfs_rq); |
| account_entity_dequeue(cfs_rq, se); |
| } |
| |
| update_load_set(&se->load, weight); |
| |
| if (se->on_rq) |
| account_entity_enqueue(cfs_rq, se); |
| } |
| |
| static inline int throttled_hierarchy(struct cfs_rq *cfs_rq); |
| |
| static void update_cfs_shares(struct cfs_rq *cfs_rq) |
| { |
| struct task_group *tg; |
| struct sched_entity *se; |
| long shares; |
| |
| tg = cfs_rq->tg; |
| se = tg->se[cpu_of(rq_of(cfs_rq))]; |
| if (!se || throttled_hierarchy(cfs_rq)) |
| return; |
| #ifndef CONFIG_SMP |
| if (likely(se->load.weight == tg->shares)) |
| return; |
| #endif |
| shares = calc_cfs_shares(cfs_rq, tg); |
| |
| reweight_entity(cfs_rq_of(se), se, shares); |
| } |
| #else /* CONFIG_FAIR_GROUP_SCHED */ |
| static inline void update_cfs_shares(struct cfs_rq *cfs_rq) |
| { |
| } |
| #endif /* CONFIG_FAIR_GROUP_SCHED */ |
| |
| #ifdef CONFIG_SMP |
| u32 sched_get_wake_up_idle(struct task_struct *p) |
| { |
| u32 enabled = p->flags & PF_WAKE_UP_IDLE; |
| |
| return !!enabled; |
| } |
| |
| int sched_set_wake_up_idle(struct task_struct *p, int wake_up_idle) |
| { |
| int enable = !!wake_up_idle; |
| |
| if (enable) |
| p->flags |= PF_WAKE_UP_IDLE; |
| else |
| p->flags &= ~PF_WAKE_UP_IDLE; |
| |
| return 0; |
| } |
| |
| /* Precomputed fixed inverse multiplies for multiplication by y^n */ |
| static const u32 runnable_avg_yN_inv[] = { |
| 0xffffffff, 0xfa83b2da, 0xf5257d14, 0xefe4b99a, 0xeac0c6e6, 0xe5b906e6, |
| 0xe0ccdeeb, 0xdbfbb796, 0xd744fcc9, 0xd2a81d91, 0xce248c14, 0xc9b9bd85, |
| 0xc5672a10, 0xc12c4cc9, 0xbd08a39e, 0xb8fbaf46, 0xb504f333, 0xb123f581, |
| 0xad583ee9, 0xa9a15ab4, 0xa5fed6a9, 0xa2704302, 0x9ef5325f, 0x9b8d39b9, |
| 0x9837f050, 0x94f4efa8, 0x91c3d373, 0x8ea4398a, 0x8b95c1e3, 0x88980e80, |
| 0x85aac367, 0x82cd8698, |
| }; |
| |
| /* |
| * Precomputed \Sum y^k { 1<=k<=n }. These are floor(true_value) to prevent |
| * over-estimates when re-combining. |
| */ |
| static const u32 runnable_avg_yN_sum[] = { |
| 0, 1002, 1982, 2941, 3880, 4798, 5697, 6576, 7437, 8279, 9103, |
| 9909,10698,11470,12226,12966,13690,14398,15091,15769,16433,17082, |
| 17718,18340,18949,19545,20128,20698,21256,21802,22336,22859,23371, |
| }; |
| |
| /* |
| * Precomputed \Sum y^k { 1<=k<=n, where n%32=0). Values are rolled down to |
| * lower integers. See Documentation/scheduler/sched-avg.txt how these |
| * were generated: |
| */ |
| static const u32 __accumulated_sum_N32[] = { |
| 0, 23371, 35056, 40899, 43820, 45281, |
| 46011, 46376, 46559, 46650, 46696, 46719, |
| }; |
| |
| /* |
| * Approximate: |
| * val * y^n, where y^32 ~= 0.5 (~1 scheduling period) |
| */ |
| static __always_inline u64 decay_load(u64 val, u64 n) |
| { |
| unsigned int local_n; |
| |
| if (!n) |
| return val; |
| else if (unlikely(n > LOAD_AVG_PERIOD * 63)) |
| return 0; |
| |
| /* after bounds checking we can collapse to 32-bit */ |
| local_n = n; |
| |
| /* |
| * As y^PERIOD = 1/2, we can combine |
| * y^n = 1/2^(n/PERIOD) * y^(n%PERIOD) |
| * With a look-up table which covers y^n (n<PERIOD) |
| * |
| * To achieve constant time decay_load. |
| */ |
| if (unlikely(local_n >= LOAD_AVG_PERIOD)) { |
| val >>= local_n / LOAD_AVG_PERIOD; |
| local_n %= LOAD_AVG_PERIOD; |
| } |
| |
| val = mul_u64_u32_shr(val, runnable_avg_yN_inv[local_n], 32); |
| return val; |
| } |
| |
| /* |
| * For updates fully spanning n periods, the contribution to runnable |
| * average will be: \Sum 1024*y^n |
| * |
| * We can compute this reasonably efficiently by combining: |
| * y^PERIOD = 1/2 with precomputed \Sum 1024*y^n {for n <PERIOD} |
| */ |
| static u32 __compute_runnable_contrib(u64 n) |
| { |
| u32 contrib = 0; |
| |
| if (likely(n <= LOAD_AVG_PERIOD)) |
| return runnable_avg_yN_sum[n]; |
| else if (unlikely(n >= LOAD_AVG_MAX_N)) |
| return LOAD_AVG_MAX; |
| |
| /* Since n < LOAD_AVG_MAX_N, n/LOAD_AVG_PERIOD < 11 */ |
| contrib = __accumulated_sum_N32[n/LOAD_AVG_PERIOD]; |
| n %= LOAD_AVG_PERIOD; |
| contrib = decay_load(contrib, n); |
| return contrib + runnable_avg_yN_sum[n]; |
| } |
| |
| #define cap_scale(v, s) ((v)*(s) >> SCHED_CAPACITY_SHIFT) |
| |
| /* |
| * We can represent the historical contribution to runnable average as the |
| * coefficients of a geometric series. To do this we sub-divide our runnable |
| * history into segments of approximately 1ms (1024us); label the segment that |
| * occurred N-ms ago p_N, with p_0 corresponding to the current period, e.g. |
| * |
| * [<- 1024us ->|<- 1024us ->|<- 1024us ->| ... |
| * p0 p1 p2 |
| * (now) (~1ms ago) (~2ms ago) |
| * |
| * Let u_i denote the fraction of p_i that the entity was runnable. |
| * |
| * We then designate the fractions u_i as our co-efficients, yielding the |
| * following representation of historical load: |
| * u_0 + u_1*y + u_2*y^2 + u_3*y^3 + ... |
| * |
| * We choose y based on the with of a reasonably scheduling period, fixing: |
| * y^32 = 0.5 |
| * |
| * This means that the contribution to load ~32ms ago (u_32) will be weighted |
| * approximately half as much as the contribution to load within the last ms |
| * (u_0). |
| * |
| * When a period "rolls over" and we have new u_0`, multiplying the previous |
| * sum again by y is sufficient to update: |
| * load_avg = u_0` + y*(u_0 + u_1*y + u_2*y^2 + ... ) |
| * = u_0 + u_1*y + u_2*y^2 + ... [re-labeling u_i --> u_{i+1}] |
| */ |
| static __always_inline int |
| __update_load_avg(u64 now, int cpu, struct sched_avg *sa, |
| unsigned long weight, int running, struct cfs_rq *cfs_rq) |
| { |
| u64 delta, scaled_delta, periods; |
| u32 contrib; |
| unsigned int delta_w, scaled_delta_w, decayed = 0; |
| unsigned long scale_freq, scale_cpu; |
| |
| delta = now - sa->last_update_time; |
| /* |
| * This should only happen when time goes backwards, which it |
| * unfortunately does during sched clock init when we swap over to TSC. |
| */ |
| if ((s64)delta < 0) { |
| sa->last_update_time = now; |
| return 0; |
| } |
| |
| /* |
| * Use 1024ns as the unit of measurement since it's a reasonable |
| * approximation of 1us and fast to compute. |
| */ |
| delta >>= 10; |
| if (!delta) |
| return 0; |
| sa->last_update_time = now; |
| |
| scale_freq = arch_scale_freq_capacity(NULL, cpu); |
| scale_cpu = arch_scale_cpu_capacity(NULL, cpu); |
| trace_sched_contrib_scale_f(cpu, scale_freq, scale_cpu); |
| |
| /* delta_w is the amount already accumulated against our next period */ |
| delta_w = sa->period_contrib; |
| if (delta + delta_w >= 1024) { |
| decayed = 1; |
| |
| /* how much left for next period will start over, we don't know yet */ |
| sa->period_contrib = 0; |
| |
| /* |
| * Now that we know we're crossing a period boundary, figure |
| * out how much from delta we need to complete the current |
| * period and accrue it. |
| */ |
| delta_w = 1024 - delta_w; |
| scaled_delta_w = cap_scale(delta_w, scale_freq); |
| if (weight) { |
| sa->load_sum += weight * scaled_delta_w; |
| if (cfs_rq) { |
| cfs_rq->runnable_load_sum += |
| weight * scaled_delta_w; |
| } |
| } |
| if (running) |
| sa->util_sum += scaled_delta_w * scale_cpu; |
| |
| delta -= delta_w; |
| |
| /* Figure out how many additional periods this update spans */ |
| periods = delta / 1024; |
| delta %= 1024; |
| |
| sa->load_sum = decay_load(sa->load_sum, periods + 1); |
| if (cfs_rq) { |
| cfs_rq->runnable_load_sum = |
| decay_load(cfs_rq->runnable_load_sum, periods + 1); |
| } |
| sa->util_sum = decay_load((u64)(sa->util_sum), periods + 1); |
| |
| /* Efficiently calculate \sum (1..n_period) 1024*y^i */ |
| contrib = __compute_runnable_contrib(periods); |
| contrib = cap_scale(contrib, scale_freq); |
| if (weight) { |
| sa->load_sum += weight * contrib; |
| if (cfs_rq) |
| cfs_rq->runnable_load_sum += weight * contrib; |
| } |
| if (running) |
| sa->util_sum += contrib * scale_cpu; |
| } |
| |
| /* Remainder of delta accrued against u_0` */ |
| scaled_delta = cap_scale(delta, scale_freq); |
| if (weight) { |
| sa->load_sum += weight * scaled_delta; |
| if (cfs_rq) |
| cfs_rq->runnable_load_sum += weight * scaled_delta; |
| } |
| if (running) |
| sa->util_sum += scaled_delta * scale_cpu; |
| |
| sa->period_contrib += delta; |
| |
| if (decayed) { |
| sa->load_avg = div_u64(sa->load_sum, LOAD_AVG_MAX); |
| if (cfs_rq) { |
| cfs_rq->runnable_load_avg = |
| div_u64(cfs_rq->runnable_load_sum, LOAD_AVG_MAX); |
| } |
| sa->util_avg = sa->util_sum / LOAD_AVG_MAX; |
| } |
| |
| return decayed; |
| } |
| |
| #ifdef CONFIG_FAIR_GROUP_SCHED |
| /** |
| * update_tg_load_avg - update the tg's load avg |
| * @cfs_rq: the cfs_rq whose avg changed |
| * @force: update regardless of how small the difference |
| * |
| * This function 'ensures': tg->load_avg := \Sum tg->cfs_rq[]->avg.load. |
| * However, because tg->load_avg is a global value there are performance |
| * considerations. |
| * |
| * In order to avoid having to look at the other cfs_rq's, we use a |
| * differential update where we store the last value we propagated. This in |
| * turn allows skipping updates if the differential is 'small'. |
| * |
| * Updating tg's load_avg is necessary before update_cfs_share() (which is |
| * done) and effective_load() (which is not done because it is too costly). |
| */ |
| static inline void update_tg_load_avg(struct cfs_rq *cfs_rq, int force) |
| { |
| long delta = cfs_rq->avg.load_avg - cfs_rq->tg_load_avg_contrib; |
| |
| /* |
| * No need to update load_avg for root_task_group as it is not used. |
| */ |
| if (cfs_rq->tg == &root_task_group) |
| return; |
| |
| if (force || abs(delta) > cfs_rq->tg_load_avg_contrib / 64) { |
| atomic_long_add(delta, &cfs_rq->tg->load_avg); |
| cfs_rq->tg_load_avg_contrib = cfs_rq->avg.load_avg; |
| } |
| } |
| |
| /* |
| * Called within set_task_rq() right before setting a task's cpu. The |
| * caller only guarantees p->pi_lock is held; no other assumptions, |
| * including the state of rq->lock, should be made. |
| */ |
| void set_task_rq_fair(struct sched_entity *se, |
| struct cfs_rq *prev, struct cfs_rq *next) |
| { |
| if (!sched_feat(ATTACH_AGE_LOAD)) |
| return; |
| |
| /* |
| * We are supposed to update the task to "current" time, then its up to |
| * date and ready to go to new CPU/cfs_rq. But we have difficulty in |
| * getting what current time is, so simply throw away the out-of-date |
| * time. This will result in the wakee task is less decayed, but giving |
| * the wakee more load sounds not bad. |
| */ |
| if (se->avg.last_update_time && prev) { |
| u64 p_last_update_time; |
| u64 n_last_update_time; |
| |
| #ifndef CONFIG_64BIT |
| u64 p_last_update_time_copy; |
| u64 n_last_update_time_copy; |
| |
| do { |
| p_last_update_time_copy = prev->load_last_update_time_copy; |
| n_last_update_time_copy = next->load_last_update_time_copy; |
| |
| smp_rmb(); |
| |
| p_last_update_time = prev->avg.last_update_time; |
| n_last_update_time = next->avg.last_update_time; |
| |
| } while (p_last_update_time != p_last_update_time_copy || |
| n_last_update_time != n_last_update_time_copy); |
| #else |
| p_last_update_time = prev->avg.last_update_time; |
| n_last_update_time = next->avg.last_update_time; |
| #endif |
| __update_load_avg(p_last_update_time, cpu_of(rq_of(prev)), |
| &se->avg, 0, 0, NULL); |
| se->avg.last_update_time = n_last_update_time; |
| } |
| } |
| #else /* CONFIG_FAIR_GROUP_SCHED */ |
| static inline void update_tg_load_avg(struct cfs_rq *cfs_rq, int force) {} |
| #endif /* CONFIG_FAIR_GROUP_SCHED */ |
| |
| static inline void cfs_rq_util_change(struct cfs_rq *cfs_rq) |
| { |
| if (&this_rq()->cfs == cfs_rq) { |
| /* |
| * There are a few boundary cases this might miss but it should |
| * get called often enough that that should (hopefully) not be |
| * a real problem -- added to that it only calls on the local |
| * CPU, so if we enqueue remotely we'll miss an update, but |
| * the next tick/schedule should update. |
| * |
| * It will not get called when we go idle, because the idle |
| * thread is a different class (!fair), nor will the utilization |
| * number include things like RT tasks. |
| * |
| * As is, the util number is not freq-invariant (we'd have to |
| * implement arch_scale_freq_capacity() for that). |
| * |
| * See cpu_util(). |
| */ |
| cpufreq_update_util(rq_of(cfs_rq), 0); |
| } |
| } |
| |
| /* |
| * Unsigned subtract and clamp on underflow. |
| * |
| * Explicitly do a load-store to ensure the intermediate value never hits |
| * memory. This allows lockless observations without ever seeing the negative |
| * values. |
| */ |
| #define sub_positive(_ptr, _val) do { \ |
| typeof(_ptr) ptr = (_ptr); \ |
| typeof(*ptr) val = (_val); \ |
| typeof(*ptr) res, var = READ_ONCE(*ptr); \ |
| res = var - val; \ |
| if (res > var) \ |
| res = 0; \ |
| WRITE_ONCE(*ptr, res); \ |
| } while (0) |
| |
| /** |
| * update_cfs_rq_load_avg - update the cfs_rq's load/util averages |
| * @now: current time, as per cfs_rq_clock_task() |
| * @cfs_rq: cfs_rq to update |
| * @update_freq: should we call cfs_rq_util_change() or will the call do so |
| * |
| * The cfs_rq avg is the direct sum of all its entities (blocked and runnable) |
| * avg. The immediate corollary is that all (fair) tasks must be attached, see |
| * post_init_entity_util_avg(). |
| * |
| * cfs_rq->avg is used for task_h_load() and update_cfs_share() for example. |
| * |
| * Returns true if the load decayed or we removed load. |
| * |
| * Since both these conditions indicate a changed cfs_rq->avg.load we should |
| * call update_tg_load_avg() when this function returns true. |
| */ |
| static inline int |
| update_cfs_rq_load_avg(u64 now, struct cfs_rq *cfs_rq, bool update_freq) |
| { |
| struct sched_avg *sa = &cfs_rq->avg; |
| int decayed, removed_load = 0, removed_util = 0; |
| |
| if (atomic_long_read(&cfs_rq->removed_load_avg)) { |
| s64 r = atomic_long_xchg(&cfs_rq->removed_load_avg, 0); |
| sub_positive(&sa->load_avg, r); |
| sub_positive(&sa->load_sum, r * LOAD_AVG_MAX); |
| removed_load = 1; |
| } |
| |
| if (atomic_long_read(&cfs_rq->removed_util_avg)) { |
| long r = atomic_long_xchg(&cfs_rq->removed_util_avg, 0); |
| sub_positive(&sa->util_avg, r); |
| sub_positive(&sa->util_sum, r * LOAD_AVG_MAX); |
| removed_util = 1; |
| } |
| |
| decayed = __update_load_avg(now, cpu_of(rq_of(cfs_rq)), sa, |
| scale_load_down(cfs_rq->load.weight), cfs_rq->curr != NULL, cfs_rq); |
| |
| #ifndef CONFIG_64BIT |
| smp_wmb(); |
| cfs_rq->load_last_update_time_copy = sa->last_update_time; |
| #endif |
| |
| if (update_freq && (decayed || removed_util)) |
| cfs_rq_util_change(cfs_rq); |
| |
| return decayed || removed_load; |
| } |
| |
| /* Update task and its cfs_rq load average */ |
| static inline void update_load_avg(struct sched_entity *se, int update_tg) |
| { |
| struct cfs_rq *cfs_rq = cfs_rq_of(se); |
| u64 now = cfs_rq_clock_task(cfs_rq); |
| struct rq *rq = rq_of(cfs_rq); |
| int cpu = cpu_of(rq); |
| |
| /* |
| * Track task load average for carrying it to new CPU after migrated, and |
| * track group sched_entity load average for task_h_load calc in migration |
| */ |
| __update_load_avg(now, cpu, &se->avg, |
| se->on_rq * scale_load_down(se->load.weight), |
| cfs_rq->curr == se, NULL); |
| |
| if (update_cfs_rq_load_avg(now, cfs_rq, true) && update_tg) |
| update_tg_load_avg(cfs_rq, 0); |
| |
| if (entity_is_task(se)) |
| trace_sched_load_avg_task(task_of(se), &se->avg); |
| trace_sched_load_avg_cpu(cpu, cfs_rq); |
| } |
| |
| /** |
| * attach_entity_load_avg - attach this entity to its cfs_rq load avg |
| * @cfs_rq: cfs_rq to attach to |
| * @se: sched_entity to attach |
| * |
| * Must call update_cfs_rq_load_avg() before this, since we rely on |
| * cfs_rq->avg.last_update_time being current. |
| */ |
| static void attach_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se) |
| { |
| if (!sched_feat(ATTACH_AGE_LOAD)) |
| goto skip_aging; |
| |
| /* |
| * If we got migrated (either between CPUs or between cgroups) we'll |
| * have aged the average right before clearing @last_update_time. |
| * |
| * Or we're fresh through post_init_entity_util_avg(). |
| */ |
| if (se->avg.last_update_time) { |
| __update_load_avg(cfs_rq->avg.last_update_time, cpu_of(rq_of(cfs_rq)), |
| &se->avg, 0, 0, NULL); |
| |
| /* |
| * XXX: we could have just aged the entire load away if we've been |
| * absent from the fair class for too long. |
| */ |
| } |
| |
| skip_aging: |
| se->avg.last_update_time = cfs_rq->avg.last_update_time; |
| cfs_rq->avg.load_avg += se->avg.load_avg; |
| cfs_rq->avg.load_sum += se->avg.load_sum; |
| cfs_rq->avg.util_avg += se->avg.util_avg; |
| cfs_rq->avg.util_sum += se->avg.util_sum; |
| |
| cfs_rq_util_change(cfs_rq); |
| } |
| |
| /** |
| * detach_entity_load_avg - detach this entity from its cfs_rq load avg |
| * @cfs_rq: cfs_rq to detach from |
| * @se: sched_entity to detach |
| * |
| * Must call update_cfs_rq_load_avg() before this, since we rely on |
| * cfs_rq->avg.last_update_time being current. |
| */ |
| static void detach_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se) |
| { |
| __update_load_avg(cfs_rq->avg.last_update_time, cpu_of(rq_of(cfs_rq)), |
| &se->avg, se->on_rq * scale_load_down(se->load.weight), |
| cfs_rq->curr == se, NULL); |
| |
| sub_positive(&cfs_rq->avg.load_avg, se->avg.load_avg); |
| sub_positive(&cfs_rq->avg.load_sum, se->avg.load_sum); |
| sub_positive(&cfs_rq->avg.util_avg, se->avg.util_avg); |
| sub_positive(&cfs_rq->avg.util_sum, se->avg.util_sum); |
| |
| cfs_rq_util_change(cfs_rq); |
| } |
| |
| /* Add the load generated by se into cfs_rq's load average */ |
| static inline void |
| enqueue_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se) |
| { |
| struct sched_avg *sa = &se->avg; |
| u64 now = cfs_rq_clock_task(cfs_rq); |
| int migrated, decayed; |
| |
| migrated = !sa->last_update_time; |
| if (!migrated) { |
| __update_load_avg(now, cpu_of(rq_of(cfs_rq)), sa, |
| se->on_rq * scale_load_down(se->load.weight), |
| cfs_rq->curr == se, NULL); |
| } |
| |
| decayed = update_cfs_rq_load_avg(now, cfs_rq, !migrated); |
| |
| cfs_rq->runnable_load_avg += sa->load_avg; |
| cfs_rq->runnable_load_sum += sa->load_sum; |
| |
| if (migrated) |
| attach_entity_load_avg(cfs_rq, se); |
| |
| if (decayed || migrated) |
| update_tg_load_avg(cfs_rq, 0); |
| } |
| |
| /* Remove the runnable load generated by se from cfs_rq's runnable load average */ |
| static inline void |
| dequeue_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se) |
| { |
| update_load_avg(se, 1); |
| |
| cfs_rq->runnable_load_avg = |
| max_t(long, cfs_rq->runnable_load_avg - se->avg.load_avg, 0); |
| cfs_rq->runnable_load_sum = |
| max_t(s64, cfs_rq->runnable_load_sum - se->avg.load_sum, 0); |
| } |
| |
| #ifndef CONFIG_64BIT |
| static inline u64 cfs_rq_last_update_time(struct cfs_rq *cfs_rq) |
| { |
| u64 last_update_time_copy; |
| u64 last_update_time; |
| |
| do { |
| last_update_time_copy = cfs_rq->load_last_update_time_copy; |
| smp_rmb(); |
| last_update_time = cfs_rq->avg.last_update_time; |
| } while (last_update_time != last_update_time_copy); |
| |
| return last_update_time; |
| } |
| #else |
| static inline u64 cfs_rq_last_update_time(struct cfs_rq *cfs_rq) |
| { |
| return cfs_rq->avg.last_update_time; |
| } |
| #endif |
| |
| /* |
| * Task first catches up with cfs_rq, and then subtract |
| * itself from the cfs_rq (task must be off the queue now). |
| */ |
| void remove_entity_load_avg(struct sched_entity *se) |
| { |
| struct cfs_rq *cfs_rq = cfs_rq_of(se); |
| u64 last_update_time; |
| |
| /* |
| * tasks cannot exit without having gone through wake_up_new_task() -> |
| * post_init_entity_util_avg() which will have added things to the |
| * cfs_rq, so we can remove unconditionally. |
| * |
| * Similarly for groups, they will have passed through |
| * post_init_entity_util_avg() before unregister_sched_fair_group() |
| * calls this. |
| */ |
| |
| last_update_time = cfs_rq_last_update_time(cfs_rq); |
| |
| __update_load_avg(last_update_time, cpu_of(rq_of(cfs_rq)), &se->avg, 0, 0, NULL); |
| atomic_long_add(se->avg.load_avg, &cfs_rq->removed_load_avg); |
| atomic_long_add(se->avg.util_avg, &cfs_rq->removed_util_avg); |
| } |
| |
| static inline unsigned long cfs_rq_runnable_load_avg(struct cfs_rq *cfs_rq) |
| { |
| return cfs_rq->runnable_load_avg; |
| } |
| |
| static inline unsigned long cfs_rq_load_avg(struct cfs_rq *cfs_rq) |
| { |
| return cfs_rq->avg.load_avg; |
| } |
| |
| static int idle_balance(struct rq *this_rq); |
| |
| #else /* CONFIG_SMP */ |
| |
| static inline int |
| update_cfs_rq_load_avg(u64 now, struct cfs_rq *cfs_rq, bool update_freq) |
| { |
| return 0; |
| } |
| |
| static inline void update_load_avg(struct sched_entity *se, int not_used) |
| { |
| cpufreq_update_util(rq_of(cfs_rq_of(se)), 0); |
| } |
| |
| static inline void |
| enqueue_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se) {} |
| static inline void |
| dequeue_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se) {} |
| static inline void remove_entity_load_avg(struct sched_entity *se) {} |
| |
| static inline void |
| attach_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se) {} |
| static inline void |
| detach_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se) {} |
| |
| static inline int idle_balance(struct rq *rq) |
| { |
| return 0; |
| } |
| |
| #endif /* CONFIG_SMP */ |
| |
| static void check_spread(struct cfs_rq *cfs_rq, struct sched_entity *se) |
| { |
| #ifdef CONFIG_SCHED_DEBUG |
| s64 d = se->vruntime - cfs_rq->min_vruntime; |
| |
| if (d < 0) |
| d = -d; |
| |
| if (d > 3*sysctl_sched_latency) |
| schedstat_inc(cfs_rq->nr_spread_over); |
| #endif |
| } |
| |
| static void |
| place_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int initial) |
| { |
| u64 vruntime = cfs_rq->min_vruntime; |
| |
| /* |
| * The 'current' period is already promised to the current tasks, |
| * however the extra weight of the new task will slow them down a |
| * little, place the new task so that it fits in the slot that |
| * stays open at the end. |
| */ |
| if (initial && sched_feat(START_DEBIT)) |
| vruntime += sched_vslice(cfs_rq, se); |
| |
| /* sleeps up to a single latency don't count. */ |
| if (!initial) { |
| unsigned long thresh = sysctl_sched_latency; |
| |
| /* |
| * Halve their sleep time's effect, to allow |
| * for a gentler effect of sleepers: |
| */ |
| if (sched_feat(GENTLE_FAIR_SLEEPERS)) |
| thresh >>= 1; |
| |
| vruntime -= thresh; |
| } |
| |
| /* ensure we never gain time by being placed backwards. */ |
| se->vruntime = max_vruntime(se->vruntime, vruntime); |
| } |
| |
| static void check_enqueue_throttle(struct cfs_rq *cfs_rq); |
| |
| static inline void check_schedstat_required(void) |
| { |
| #ifdef CONFIG_SCHEDSTATS |
| if (schedstat_enabled()) |
| return; |
| |
| /* Force schedstat enabled if a dependent tracepoint is active */ |
| if (trace_sched_stat_wait_enabled() || |
| trace_sched_stat_sleep_enabled() || |
| trace_sched_stat_iowait_enabled() || |
| trace_sched_stat_blocked_enabled() || |
| trace_sched_stat_runtime_enabled()) { |
| printk_deferred_once("Scheduler tracepoints stat_sleep, stat_iowait, " |
| "stat_blocked and stat_runtime require the " |
| "kernel parameter schedstats=enabled or " |
| "kernel.sched_schedstats=1\n"); |
| } |
| #endif |
| } |
| |
| |
| /* |
| * MIGRATION |
| * |
| * dequeue |
| * update_curr() |
| * update_min_vruntime() |
| * vruntime -= min_vruntime |
| * |
| * enqueue |
| * update_curr() |
| * update_min_vruntime() |
| * vruntime += min_vruntime |
| * |
| * this way the vruntime transition between RQs is done when both |
| * min_vruntime are up-to-date. |
| * |
| * WAKEUP (remote) |
| * |
| * ->migrate_task_rq_fair() (p->state == TASK_WAKING) |
| * vruntime -= min_vruntime |
| * |
| * enqueue |
| * update_curr() |
| * update_min_vruntime() |
| * vruntime += min_vruntime |
| * |
| * this way we don't have the most up-to-date min_vruntime on the originating |
| * CPU and an up-to-date min_vruntime on the destination CPU. |
| */ |
| |
| static void |
| enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags) |
| { |
| bool renorm = !(flags & ENQUEUE_WAKEUP) || (flags & ENQUEUE_MIGRATED); |
| bool curr = cfs_rq->curr == se; |
| |
| /* |
| * If we're the current task, we must renormalise before calling |
| * update_curr(). |
| */ |
| if (renorm && curr) |
| se->vruntime += cfs_rq->min_vruntime; |
| |
| update_curr(cfs_rq); |
| |
| /* |
| * Otherwise, renormalise after, such that we're placed at the current |
| * moment in time, instead of some random moment in the past. Being |
| * placed in the past could significantly boost this task to the |
| * fairness detriment of existing tasks. |
| */ |
| if (renorm && !curr) |
| se->vruntime += cfs_rq->min_vruntime; |
| |
| enqueue_entity_load_avg(cfs_rq, se); |
| account_entity_enqueue(cfs_rq, se); |
| update_cfs_shares(cfs_rq); |
| |
| if (flags & ENQUEUE_WAKEUP) |
| place_entity(cfs_rq, se, 0); |
| |
| check_schedstat_required(); |
| update_stats_enqueue(cfs_rq, se, flags); |
| check_spread(cfs_rq, se); |
| if (!curr) |
| __enqueue_entity(cfs_rq, se); |
| se->on_rq = 1; |
| |
| if (cfs_rq->nr_running == 1) { |
| list_add_leaf_cfs_rq(cfs_rq); |
| check_enqueue_throttle(cfs_rq); |
| } |
| } |
| |
| static void __clear_buddies_last(struct sched_entity *se) |
| { |
| for_each_sched_entity(se) { |
| struct cfs_rq *cfs_rq = cfs_rq_of(se); |
| if (cfs_rq->last != se) |
| break; |
| |
| cfs_rq->last = NULL; |
| } |
| } |
| |
| static void __clear_buddies_next(struct sched_entity *se) |
| { |
| for_each_sched_entity(se) { |
| struct cfs_rq *cfs_rq = cfs_rq_of(se); |
| if (cfs_rq->next != se) |
| break; |
| |
| cfs_rq->next = NULL; |
| } |
| } |
| |
| static void __clear_buddies_skip(struct sched_entity *se) |
| { |
| for_each_sched_entity(se) { |
| struct cfs_rq *cfs_rq = cfs_rq_of(se); |
| if (cfs_rq->skip != se) |
| break; |
| |
| cfs_rq->skip = NULL; |
| } |
| } |
| |
| static void clear_buddies(struct cfs_rq *cfs_rq, struct sched_entity *se) |
| { |
| if (cfs_rq->last == se) |
| __clear_buddies_last(se); |
| |
| if (cfs_rq->next == se) |
| __clear_buddies_next(se); |
| |
| if (cfs_rq->skip == se) |
| __clear_buddies_skip(se); |
| } |
| |
| static __always_inline void return_cfs_rq_runtime(struct cfs_rq *cfs_rq); |
| |
| static void |
| dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags) |
| { |
| /* |
| * Update run-time statistics of the 'current'. |
| */ |
| update_curr(cfs_rq); |
| dequeue_entity_load_avg(cfs_rq, se); |
| |
| update_stats_dequeue(cfs_rq, se, flags); |
| |
| clear_buddies(cfs_rq, se); |
| |
| if (se != cfs_rq->curr) |
| __dequeue_entity(cfs_rq, se); |
| se->on_rq = 0; |
| account_entity_dequeue(cfs_rq, se); |
| |
| /* |
| * Normalize after update_curr(); which will also have moved |
| * min_vruntime if @se is the one holding it back. But before doing |
| * update_min_vruntime() again, which will discount @se's position and |
| * can move min_vruntime forward still more. |
| */ |
| if (!(flags & DEQUEUE_SLEEP)) |
| se->vruntime -= cfs_rq->min_vruntime; |
| |
| /* return excess runtime on last dequeue */ |
| return_cfs_rq_runtime(cfs_rq); |
| |
| update_cfs_shares(cfs_rq); |
| |
| /* |
| * Now advance min_vruntime if @se was the entity holding it back, |
| * except when: DEQUEUE_SAVE && !DEQUEUE_MOVE, in this case we'll be |
| * put back on, and if we advance min_vruntime, we'll be placed back |
| * further than we started -- ie. we'll be penalized. |
| */ |
| if ((flags & (DEQUEUE_SAVE | DEQUEUE_MOVE)) == DEQUEUE_SAVE) |
| update_min_vruntime(cfs_rq); |
| } |
| |
| /* |
| * Preempt the current task with a newly woken task if needed: |
| */ |
| static void |
| check_preempt_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr) |
| { |
| unsigned long ideal_runtime, delta_exec; |
| struct sched_entity *se; |
| s64 delta; |
| |
| ideal_runtime = sched_slice(cfs_rq, curr); |
| delta_exec = curr->sum_exec_runtime - curr->prev_sum_exec_runtime; |
| if (delta_exec > ideal_runtime) { |
| resched_curr(rq_of(cfs_rq)); |
| /* |
| * The current task ran long enough, ensure it doesn't get |
| * re-elected due to buddy favours. |
| */ |
| clear_buddies(cfs_rq, curr); |
| return; |
| } |
| |
| /* |
| * Ensure that a task that missed wakeup preemption by a |
| * narrow margin doesn't have to wait for a full slice. |
| * This also mitigates buddy induced latencies under load. |
| */ |
| if (delta_exec < sysctl_sched_min_granularity) |
| return; |
| |
| se = __pick_first_entity(cfs_rq); |
| delta = curr->vruntime - se->vruntime; |
| |
| if (delta < 0) |
| return; |
| |
| if (delta > ideal_runtime) |
| resched_curr(rq_of(cfs_rq)); |
| } |
| |
| static void |
| set_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *se) |
| { |
| /* 'current' is not kept within the tree. */ |
| if (se->on_rq) { |
| /* |
| * Any task has to be enqueued before it get to execute on |
| * a CPU. So account for the time it spent waiting on the |
| * runqueue. |
| */ |
| update_stats_wait_end(cfs_rq, se); |
| __dequeue_entity(cfs_rq, se); |
| update_load_avg(se, 1); |
| } |
| |
| update_stats_curr_start(cfs_rq, se); |
| cfs_rq->curr = se; |
| |
| /* |
| * Track our maximum slice length, if the CPU's load is at |
| * least twice that of our own weight (i.e. dont track it |
| * when there are only lesser-weight tasks around): |
| */ |
| if (schedstat_enabled() && rq_of(cfs_rq)->load.weight >= 2*se->load.weight) { |
| schedstat_set(se->statistics.slice_max, |
| max((u64)schedstat_val(se->statistics.slice_max), |
| se->sum_exec_runtime - se->prev_sum_exec_runtime)); |
| } |
| |
| se->prev_sum_exec_runtime = se->sum_exec_runtime; |
| } |
| |
| static int |
| wakeup_preempt_entity(struct sched_entity *curr, struct sched_entity *se); |
| |
| /* |
| * Pick the next process, keeping these things in mind, in this order: |
| * 1) keep things fair between processes/task groups |
| * 2) pick the "next" process, since someone really wants that to run |
| * 3) pick the "last" process, for cache locality |
| * 4) do not run the "skip" process, if something else is available |
| */ |
| static struct sched_entity * |
| pick_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *curr) |
| { |
| struct sched_entity *left = __pick_first_entity(cfs_rq); |
| struct sched_entity *se; |
| |
| /* |
| * If curr is set we have to see if its left of the leftmost entity |
| * still in the tree, provided there was anything in the tree at all. |
| */ |
| if (!left || (curr && entity_before(curr, left))) |
| left = curr; |
| |
| se = left; /* ideally we run the leftmost entity */ |
| |
| /* |
| * Avoid running the skip buddy, if running something else can |
| * be done without getting too unfair. |
| */ |
| if (cfs_rq->skip == se) { |
| struct sched_entity *second; |
| |
| if (se == curr) { |
| second = __pick_first_entity(cfs_rq); |
| } else { |
| second = __pick_next_entity(se); |
| if (!second || (curr && entity_before(curr, second))) |
| second = curr; |
| } |
| |
| if (second && wakeup_preempt_entity(second, left) < 1) |
| se = second; |
| } |
| |
| /* |
| * Prefer last buddy, try to return the CPU to a preempted task. |
| */ |
| if (cfs_rq->last && wakeup_preempt_entity(cfs_rq->last, left) < 1) |
| se = cfs_rq->last; |
| |
| /* |
| * Someone really wants this to run. If it's not unfair, run it. |
| */ |
| if (cfs_rq->next && wakeup_preempt_entity(cfs_rq->next, left) < 1) |
| se = cfs_rq->next; |
| |
| clear_buddies(cfs_rq, se); |
| |
| return se; |
| } |
| |
| static bool check_cfs_rq_runtime(struct cfs_rq *cfs_rq); |
| |
| static void put_prev_entity(struct cfs_rq *cfs_rq, struct sched_entity *prev) |
| { |
| /* |
| * If still on the runqueue then deactivate_task() |
| * was not called and update_curr() has to be done: |
| */ |
| if (prev->on_rq) |
| update_curr(cfs_rq); |
| |
| /* throttle cfs_rqs exceeding runtime */ |
| check_cfs_rq_runtime(cfs_rq); |
| |
| check_spread(cfs_rq, prev); |
| |
| if (prev->on_rq) { |
| update_stats_wait_start(cfs_rq, prev); |
| /* Put 'current' back into the tree. */ |
| __enqueue_entity(cfs_rq, prev); |
| /* in !on_rq case, update occurred at dequeue */ |
| update_load_avg(prev, 0); |
| } |
| cfs_rq->curr = NULL; |
| } |
| |
| static void |
| entity_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr, int queued) |
| { |
| /* |
| * Update run-time statistics of the 'current'. |
| */ |
| update_curr(cfs_rq); |
| |
| /* |
| * Ensure that runnable average is periodically updated. |
| */ |
| update_load_avg(curr, 1); |
| update_cfs_shares(cfs_rq); |
| |
| #ifdef CONFIG_SCHED_HRTICK |
| /* |
| * queued ticks are scheduled to match the slice, so don't bother |
| * validating it and just reschedule. |
| */ |
| if (queued) { |
| resched_curr(rq_of(cfs_rq)); |
| return; |
| } |
| /* |
| * don't let the period tick interfere with the hrtick preemption |
| */ |
| if (!sched_feat(DOUBLE_TICK) && |
| hrtimer_active(&rq_of(cfs_rq)->hrtick_timer)) |
| return; |
| #endif |
| |
| if (cfs_rq->nr_running > 1) |
| check_preempt_tick(cfs_rq, curr); |
| } |
| |
| |
| /************************************************** |
| * CFS bandwidth control machinery |
| */ |
| |
| #ifdef CONFIG_CFS_BANDWIDTH |
| |
| #ifdef HAVE_JUMP_LABEL |
| static struct static_key __cfs_bandwidth_used; |
| |
| static inline bool cfs_bandwidth_used(void) |
| { |
| return static_key_false(&__cfs_bandwidth_used); |
| } |
| |
| void cfs_bandwidth_usage_inc(void) |
| { |
| static_key_slow_inc(&__cfs_bandwidth_used); |
| } |
| |
| void cfs_bandwidth_usage_dec(void) |
| { |
| static_key_slow_dec(&__cfs_bandwidth_used); |
| } |
| #else /* HAVE_JUMP_LABEL */ |
| static bool cfs_bandwidth_used(void) |
| { |
| return true; |
| } |
| |
| void cfs_bandwidth_usage_inc(void) {} |
| void cfs_bandwidth_usage_dec(void) {} |
| #endif /* HAVE_JUMP_LABEL */ |
| |
| /* |
| * default period for cfs group bandwidth. |
| * default: 0.1s, units: nanoseconds |
| */ |
| static inline u64 default_cfs_period(void) |
| { |
| return 100000000ULL; |
| } |
| |
| static inline u64 sched_cfs_bandwidth_slice(void) |
| { |
| return (u64)sysctl_sched_cfs_bandwidth_slice * NSEC_PER_USEC; |
| } |
| |
| /* |
| * Replenish runtime according to assigned quota and update expiration time. |
| * We use sched_clock_cpu directly instead of rq->clock to avoid adding |
| * additional synchronization around rq->lock. |
| * |
| * requires cfs_b->lock |
| */ |
| void __refill_cfs_bandwidth_runtime(struct cfs_bandwidth *cfs_b) |
| { |
| u64 now; |
| |
| if (cfs_b->quota == RUNTIME_INF) |
| return; |
| |
| now = sched_clock_cpu(smp_processor_id()); |
| cfs_b->runtime = cfs_b->quota; |
| cfs_b->runtime_expires = now + ktime_to_ns(cfs_b->period); |
| } |
| |
| static inline struct cfs_bandwidth *tg_cfs_bandwidth(struct task_group *tg) |
| { |
| return &tg->cfs_bandwidth; |
| } |
| |
| /* rq->task_clock normalized against any time this cfs_rq has spent throttled */ |
| static inline u64 cfs_rq_clock_task(struct cfs_rq *cfs_rq) |
| { |
| if (unlikely(cfs_rq->throttle_count)) |
| return cfs_rq->throttled_clock_task - cfs_rq->throttled_clock_task_time; |
| |
| return rq_clock_task(rq_of(cfs_rq)) - cfs_rq->throttled_clock_task_time; |
| } |
| |
| /* returns 0 on failure to allocate runtime */ |
| static int assign_cfs_rq_runtime(struct cfs_rq *cfs_rq) |
| { |
| struct task_group *tg = cfs_rq->tg; |
| struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(tg); |
| u64 amount = 0, min_amount, expires; |
| |
| /* note: this is a positive sum as runtime_remaining <= 0 */ |
| min_amount = sched_cfs_bandwidth_slice() - cfs_rq->runtime_remaining; |
| |
| raw_spin_lock(&cfs_b->lock); |
| if (cfs_b->quota == RUNTIME_INF) |
| amount = min_amount; |
| else { |
| start_cfs_bandwidth(cfs_b); |
| |
| if (cfs_b->runtime > 0) { |
| amount = min(cfs_b->runtime, min_amount); |
| cfs_b->runtime -= amount; |
| cfs_b->idle = 0; |
| } |
| } |
| expires = cfs_b->runtime_expires; |
| raw_spin_unlock(&cfs_b->lock); |
| |
| cfs_rq->runtime_remaining += amount; |
| /* |
| * we may have advanced our local expiration to account for allowed |
| * spread between our sched_clock and the one on which runtime was |
| * issued. |
| */ |
| if ((s64)(expires - cfs_rq->runtime_expires) > 0) |
| cfs_rq->runtime_expires = expires; |
| |
| return cfs_rq->runtime_remaining > 0; |
| } |
| |
| /* |
| * Note: This depends on the synchronization provided by sched_clock and the |
| * fact that rq->clock snapshots this value. |
| */ |
| static void expire_cfs_rq_runtime(struct cfs_rq *cfs_rq) |
| { |
| struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg); |
| |
| /* if the deadline is ahead of our clock, nothing to do */ |
| if (likely((s64)(rq_clock(rq_of(cfs_rq)) - cfs_rq->runtime_expires) < 0)) |
| return; |
| |
| if (cfs_rq->runtime_remaining < 0) |
| return; |
| |
| /* |
| * If the local deadline has passed we have to consider the |
| * possibility that our sched_clock is 'fast' and the global deadline |
| * has not truly expired. |
| * |
| * Fortunately we can check determine whether this the case by checking |
| * whether the global deadline has advanced. It is valid to compare |
| * cfs_b->runtime_expires without any locks since we only care about |
| * exact equality, so a partial write will still work. |
| */ |
| |
| if (cfs_rq->runtime_expires != cfs_b->runtime_expires) { |
| /* extend local deadline, drift is bounded above by 2 ticks */ |
| cfs_rq->runtime_expires += TICK_NSEC; |
| } else { |
| /* global deadline is ahead, expiration has passed */ |
| cfs_rq->runtime_remaining = 0; |
| } |
| } |
| |
| static void __account_cfs_rq_runtime(struct cfs_rq *cfs_rq, u64 delta_exec) |
| { |
| /* dock delta_exec before expiring quota (as it could span periods) */ |
| cfs_rq->runtime_remaining -= delta_exec; |
| expire_cfs_rq_runtime(cfs_rq); |
| |
| if (likely(cfs_rq->runtime_remaining > 0)) |
| return; |
| |
| /* |
| * if we're unable to extend our runtime we resched so that the active |
| * hierarchy can be throttled |
| */ |
| if (!assign_cfs_rq_runtime(cfs_rq) && likely(cfs_rq->curr)) |
| resched_curr(rq_of(cfs_rq)); |
| } |
| |
| static __always_inline |
| void account_cfs_rq_runtime(struct cfs_rq *cfs_rq, u64 delta_exec) |
| { |
| if (!cfs_bandwidth_used() || !cfs_rq->runtime_enabled) |
| return; |
| |
| __account_cfs_rq_runtime(cfs_rq, delta_exec); |
| } |
| |
| static inline int cfs_rq_throttled(struct cfs_rq *cfs_rq) |
| { |
| return cfs_bandwidth_used() && cfs_rq->throttled; |
| } |
| |
| /* check whether cfs_rq, or any parent, is throttled */ |
| static inline int throttled_hierarchy(struct cfs_rq *cfs_rq) |
| { |
| return cfs_bandwidth_used() && cfs_rq->throttle_count; |
| } |
| |
| /* |
| * Ensure that neither of the group entities corresponding to src_cpu or |
| * dest_cpu are members of a throttled hierarchy when performing group |
| * load-balance operations. |
| */ |
| static inline int throttled_lb_pair(struct task_group *tg, |
| int src_cpu, int dest_cpu) |
| { |
| struct cfs_rq *src_cfs_rq, *dest_cfs_rq; |
| |
| src_cfs_rq = tg->cfs_rq[src_cpu]; |
| dest_cfs_rq = tg->cfs_rq[dest_cpu]; |
| |
| return throttled_hierarchy(src_cfs_rq) || |
| throttled_hierarchy(dest_cfs_rq); |
| } |
| |
| /* updated child weight may affect parent so we have to do this bottom up */ |
| static int tg_unthrottle_up(struct task_group *tg, void *data) |
| { |
| struct rq *rq = data; |
| struct cfs_rq *cfs_rq = tg->cfs_rq[cpu_of(rq)]; |
| |
| cfs_rq->throttle_count--; |
| if (!cfs_rq->throttle_count) { |
| /* adjust cfs_rq_clock_task() */ |
| cfs_rq->throttled_clock_task_time += rq_clock_task(rq) - |
| cfs_rq->throttled_clock_task; |
| } |
| |
| return 0; |
| } |
| |
| static int tg_throttle_down(struct task_group *tg, void *data) |
| { |
| struct rq *rq = data; |
| struct cfs_rq *cfs_rq = tg->cfs_rq[cpu_of(rq)]; |
| |
| /* group is entering throttled state, stop time */ |
| if (!cfs_rq->throttle_count) |
| cfs_rq->throttled_clock_task = rq_clock_task(rq); |
| cfs_rq->throttle_count++; |
| |
| return 0; |
| } |
| |
| static void throttle_cfs_rq(struct cfs_rq *cfs_rq) |
| { |
| struct rq *rq = rq_of(cfs_rq); |
| struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg); |
| struct sched_entity *se; |
| long task_delta, dequeue = 1; |
| bool empty; |
| |
| se = cfs_rq->tg->se[cpu_of(rq_of(cfs_rq))]; |
| |
| /* freeze hierarchy runnable averages while throttled */ |
| rcu_read_lock(); |
| walk_tg_tree_from(cfs_rq->tg, tg_throttle_down, tg_nop, (void *)rq); |
| rcu_read_unlock(); |
| |
| task_delta = cfs_rq->h_nr_running; |
| for_each_sched_entity(se) { |
| struct cfs_rq *qcfs_rq = cfs_rq_of(se); |
| /* throttled entity or throttle-on-deactivate */ |
| if (!se->on_rq) |
| break; |
| |
| if (dequeue) |
| dequeue_entity(qcfs_rq, se, DEQUEUE_SLEEP); |
| qcfs_rq->h_nr_running -= task_delta; |
| dec_throttled_cfs_rq_hmp_stats(&qcfs_rq->hmp_stats, cfs_rq); |
| |
| if (qcfs_rq->load.weight) |
| dequeue = 0; |
| } |
| |
| if (!se) { |
| sub_nr_running(rq, task_delta); |
| dec_throttled_cfs_rq_hmp_stats(&rq->hmp_stats, cfs_rq); |
| } |
| |
| cfs_rq->throttled = 1; |
| cfs_rq->throttled_clock = rq_clock(rq); |
| raw_spin_lock(&cfs_b->lock); |
| empty = list_empty(&cfs_b->throttled_cfs_rq); |
| |
| /* |
| * Add to the _head_ of the list, so that an already-started |
| * distribute_cfs_runtime will not see us |
| */ |
| list_add_rcu(&cfs_rq->throttled_list, &cfs_b->throttled_cfs_rq); |
| |
| /* |
| * If we're the first throttled task, make sure the bandwidth |
| * timer is running. |
| */ |
| if (empty) |
| start_cfs_bandwidth(cfs_b); |
| |
| raw_spin_unlock(&cfs_b->lock); |
| |
| /* Log effect on hmp stats after throttling */ |
| trace_sched_cpu_load_cgroup(rq, idle_cpu(cpu_of(rq)), |
| sched_irqload(cpu_of(rq)), |
| power_cost(cpu_of(rq), 0), |
| cpu_temp(cpu_of(rq))); |
| } |
| |
| void unthrottle_cfs_rq(struct cfs_rq *cfs_rq) |
| { |
| struct rq *rq = rq_of(cfs_rq); |
| struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg); |
| struct sched_entity *se; |
| int enqueue = 1; |
| long task_delta; |
| struct cfs_rq *tcfs_rq __maybe_unused = cfs_rq; |
| |
| se = cfs_rq->tg->se[cpu_of(rq)]; |
| |
| cfs_rq->throttled = 0; |
| |
| update_rq_clock(rq); |
| |
| raw_spin_lock(&cfs_b->lock); |
| cfs_b->throttled_time += rq_clock(rq) - cfs_rq->throttled_clock; |
| list_del_rcu(&cfs_rq->throttled_list); |
| raw_spin_unlock(&cfs_b->lock); |
| |
| /* update hierarchical throttle state */ |
| walk_tg_tree_from(cfs_rq->tg, tg_nop, tg_unthrottle_up, (void *)rq); |
| |
| if (!cfs_rq->load.weight) |
| return; |
| |
| task_delta = cfs_rq->h_nr_running; |
| for_each_sched_entity(se) { |
| if (se->on_rq) |
| enqueue = 0; |
| |
| cfs_rq = cfs_rq_of(se); |
| if (enqueue) |
| enqueue_entity(cfs_rq, se, ENQUEUE_WAKEUP); |
| cfs_rq->h_nr_running += task_delta; |
| inc_throttled_cfs_rq_hmp_stats(&cfs_rq->hmp_stats, tcfs_rq); |
| |
| if (cfs_rq_throttled(cfs_rq)) |
| break; |
| } |
| |
| if (!se) { |
| add_nr_running(rq, task_delta); |
| inc_throttled_cfs_rq_hmp_stats(&rq->hmp_stats, tcfs_rq); |
| } |
| |
| /* determine whether we need to wake up potentially idle cpu */ |
| if (rq->curr == rq->idle && rq->cfs.nr_running) |
| resched_curr(rq); |
| |
| /* Log effect on hmp stats after un-throttling */ |
| trace_sched_cpu_load_cgroup(rq, idle_cpu(cpu_of(rq)), |
| sched_irqload(cpu_of(rq)), |
| power_cost(cpu_of(rq), 0), |
| cpu_temp(cpu_of(rq))); |
| } |
| |
| static u64 distribute_cfs_runtime(struct cfs_bandwidth *cfs_b, |
| u64 remaining, u64 expires) |
| { |
| struct cfs_rq *cfs_rq; |
| u64 runtime; |
| u64 starting_runtime = remaining; |
| |
| rcu_read_lock(); |
| list_for_each_entry_rcu(cfs_rq, &cfs_b->throttled_cfs_rq, |
| throttled_list) { |
| struct rq *rq = rq_of(cfs_rq); |
| |
| raw_spin_lock(&rq->lock); |
| if (!cfs_rq_throttled(cfs_rq)) |
| goto next; |
| |
| runtime = -cfs_rq->runtime_remaining + 1; |
| if (runtime > remaining) |
| runtime = remaining; |
| remaining -= runtime; |
| |
| cfs_rq->runtime_remaining += runtime; |
| cfs_rq->runtime_expires = expires; |
| |
| /* we check whether we're throttled above */ |
| if (cfs_rq->runtime_remaining > 0) |
| unthrottle_cfs_rq(cfs_rq); |
| |
| next: |
| raw_spin_unlock(&rq->lock); |
| |
| if (!remaining) |
| break; |
| } |
| rcu_read_unlock(); |
| |
| return starting_runtime - remaining; |
| } |
| |
| /* |
| * Responsible for refilling a task_group's bandwidth and unthrottling its |
| * cfs_rqs as appropriate. If there has been no activity within the last |
| * period the timer is deactivated until scheduling resumes; cfs_b->idle is |
| * used to track this state. |
| */ |
| static int do_sched_cfs_period_timer(struct cfs_bandwidth *cfs_b, int overrun) |
| { |
| u64 runtime, runtime_expires; |
| int throttled; |
| |
| /* no need to continue the timer with no bandwidth constraint */ |
| if (cfs_b->quota == RUNTIME_INF) |
| goto out_deactivate; |
| |
| throttled = !list_empty(&cfs_b->throttled_cfs_rq); |
| cfs_b->nr_periods += overrun; |
| |
| /* |
| * idle depends on !throttled (for the case of a large deficit), and if |
| * we're going inactive then everything else can be deferred |
| */ |
| if (cfs_b->idle && !throttled) |
| goto out_deactivate; |
| |
| __refill_cfs_bandwidth_runtime(cfs_b); |
| |
| if (!throttled) { |
| /* mark as potentially idle for the upcoming period */ |
| cfs_b->idle = 1; |
| return 0; |
| } |
| |
| /* account preceding periods in which throttling occurred */ |
| cfs_b->nr_throttled += overrun; |
| |
| runtime_expires = cfs_b->runtime_expires; |
| |
| /* |
| * This check is repeated as we are holding onto the new bandwidth while |
| * we unthrottle. This can potentially race with an unthrottled group |
| * trying to acquire new bandwidth from the global pool. This can result |
| * in us over-using our runtime if it is all used during this loop, but |
| * only by limited amounts in that extreme case. |
| */ |
| while (throttled && cfs_b->runtime > 0) { |
| runtime = cfs_b->runtime; |
| raw_spin_unlock(&cfs_b->lock); |
| /* we can't nest cfs_b->lock while distributing bandwidth */ |
| runtime = distribute_cfs_runtime(cfs_b, runtime, |
| runtime_expires); |
| raw_spin_lock(&cfs_b->lock); |
| |
| throttled = !list_empty(&cfs_b->throttled_cfs_rq); |
| |
| cfs_b->runtime -= min(runtime, cfs_b->runtime); |
| } |
| |
| /* |
| * While we are ensured activity in the period following an |
| * unthrottle, this also covers the case in which the new bandwidth is |
| * insufficient to cover the existing bandwidth deficit. (Forcing the |
| * timer to remain active while there are any throttled entities.) |
| */ |
| cfs_b->idle = 0; |
| |
| return 0; |
| |
| out_deactivate: |
| return 1; |
| } |
| |
| /* a cfs_rq won't donate quota below this amount */ |
| static const u64 min_cfs_rq_runtime = 1 * NSEC_PER_MSEC; |
| /* minimum remaining period time to redistribute slack quota */ |
| static const u64 min_bandwidth_expiration = 2 * NSEC_PER_MSEC; |
| /* how long we wait to gather additional slack before distributing */ |
| static const u64 cfs_bandwidth_slack_period = 5 * NSEC_PER_MSEC; |
| |
| /* |
| * Are we near the end of the current quota period? |
| * |
| * Requires cfs_b->lock for hrtimer_expires_remaining to be safe against the |
| * hrtimer base being cleared by hrtimer_start. In the case of |
| * migrate_hrtimers, base is never cleared, so we are fine. |
| */ |
| static int runtime_refresh_within(struct cfs_bandwidth *cfs_b, u64 min_expire) |
| { |
| struct hrtimer *refresh_timer = &cfs_b->period_timer; |
| u64 remaining; |
| |
| /* if the call-back is running a quota refresh is already occurring */ |
| if (hrtimer_callback_running(refresh_timer)) |
| return 1; |
| |
| /* is a quota refresh about to occur? */ |
| remaining = ktime_to_ns(hrtimer_expires_remaining(refresh_timer)); |
| if (remaining < min_expire) |
| return 1; |
| |
| return 0; |
| } |
| |
| static void start_cfs_slack_bandwidth(struct cfs_bandwidth *cfs_b) |
| { |
| u64 min_left = cfs_bandwidth_slack_period + min_bandwidth_expiration; |
| |
| /* if there's a quota refresh soon don't bother with slack */ |
| if (runtime_refresh_within(cfs_b, min_left)) |
| return; |
| |
| hrtimer_start(&cfs_b->slack_timer, |
| ns_to_ktime(cfs_bandwidth_slack_period), |
| HRTIMER_MODE_REL); |
| } |
| |
| /* we know any runtime found here is valid as update_curr() precedes return */ |
| static void __return_cfs_rq_runtime(struct cfs_rq *cfs_rq) |
| { |
| struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg); |
| s64 slack_runtime = cfs_rq->runtime_remaining - min_cfs_rq_runtime; |
| |
| if (slack_runtime <= 0) |
| return; |
| |
| raw_spin_lock(&cfs_b->lock); |
| if (cfs_b->quota != RUNTIME_INF && |
| cfs_rq->runtime_expires == cfs_b->runtime_expires) { |
| cfs_b->runtime += slack_runtime; |
| |
| /* we are under rq->lock, defer unthrottling using a timer */ |
| if (cfs_b->runtime > sched_cfs_bandwidth_slice() && |
| !list_empty(&cfs_b->throttled_cfs_rq)) |
| start_cfs_slack_bandwidth(cfs_b); |
| } |
| raw_spin_unlock(&cfs_b->lock); |
| |
| /* even if it's not valid for return we don't want to try again */ |
| cfs_rq->runtime_remaining -= slack_runtime; |
| } |
| |
| static __always_inline void return_cfs_rq_runtime(struct cfs_rq *cfs_rq) |
| { |
| if (!cfs_bandwidth_used()) |
| return; |
| |
| if (!cfs_rq->runtime_enabled || cfs_rq->nr_running) |
| return; |
| |
| __return_cfs_rq_runtime(cfs_rq); |
| } |
| |
| /* |
| * This is done with a timer (instead of inline with bandwidth return) since |
| * it's necessary to juggle rq->locks to unthrottle their respective cfs_rqs. |
| */ |
| static void do_sched_cfs_slack_timer(struct cfs_bandwidth *cfs_b) |
| { |
| u64 runtime = 0, slice = sched_cfs_bandwidth_slice(); |
| u64 expires; |
| |
| /* confirm we're still not at a refresh boundary */ |
| raw_spin_lock(&cfs_b->lock); |
| if (runtime_refresh_within(cfs_b, min_bandwidth_expiration)) { |
| raw_spin_unlock(&cfs_b->lock); |
| return; |
| } |
| |
| if (cfs_b->quota != RUNTIME_INF && cfs_b->runtime > slice) |
| runtime = cfs_b->runtime; |
| |
| expires = cfs_b->runtime_expires; |
| raw_spin_unlock(&cfs_b->lock); |
| |
| if (!runtime) |
| return; |
| |
| runtime = distribute_cfs_runtime(cfs_b, runtime, expires); |
| |
| raw_spin_lock(&cfs_b->lock); |
| if (expires == cfs_b->runtime_expires) |
| cfs_b->runtime -= min(runtime, cfs_b->runtime); |
| raw_spin_unlock(&cfs_b->lock); |
| } |
| |
| /* |
| * When a group wakes up we want to make sure that its quota is not already |
| * expired/exceeded, otherwise it may be allowed to steal additional ticks of |
| * runtime as update_curr() throttling can not not trigger until it's on-rq. |
| */ |
| static void check_enqueue_throttle(struct cfs_rq *cfs_rq) |
| { |
| if (!cfs_bandwidth_used()) |
| return; |
| |
| /* an active group must be handled by the update_curr()->put() path */ |
| if (!cfs_rq->runtime_enabled || cfs_rq->curr) |
| return; |
| |
| /* ensure the group is not already throttled */ |
| if (cfs_rq_throttled(cfs_rq)) |
| return; |
| |
| /* update runtime allocation */ |
| account_cfs_rq_runtime(cfs_rq, 0); |
| if (cfs_rq->runtime_remaining <= 0) |
| throttle_cfs_rq(cfs_rq); |
| } |
| |
| static void sync_throttle(struct task_group *tg, int cpu) |
| { |
| struct cfs_rq *pcfs_rq, *cfs_rq; |
| |
| if (!cfs_bandwidth_used()) |
| return; |
| |
| if (!tg->parent) |
| return; |
| |
| cfs_rq = tg->cfs_rq[cpu]; |
| pcfs_rq = tg->parent->cfs_rq[cpu]; |
| |
| cfs_rq->throttle_count = pcfs_rq->throttle_count; |
| cfs_rq->throttled_clock_task = rq_clock_task(cpu_rq(cpu)); |
| } |
| |
| /* conditionally throttle active cfs_rq's from put_prev_entity() */ |
| static bool check_cfs_rq_runtime(struct cfs_rq *cfs_rq) |
| { |
| if (!cfs_bandwidth_used()) |
| return false; |
| |
| if (likely(!cfs_rq->runtime_enabled || cfs_rq->runtime_remaining > 0)) |
| return false; |
| |
| /* |
| * it's possible for a throttled entity to be forced into a running |
| * state (e.g. set_curr_task), in this case we're finished. |
| */ |
| if (cfs_rq_throttled(cfs_rq)) |
| return true; |
| |
| throttle_cfs_rq(cfs_rq); |
| return true; |
| } |
| |
| static enum hrtimer_restart sched_cfs_slack_timer(struct hrtimer *timer) |
| { |
| struct cfs_bandwidth *cfs_b = |
| container_of(timer, struct cfs_bandwidth, slack_timer); |
| |
| do_sched_cfs_slack_timer(cfs_b); |
| |
| return HRTIMER_NORESTART; |
| } |
| |
| static enum hrtimer_restart sched_cfs_period_timer(struct hrtimer *timer) |
| { |
| struct cfs_bandwidth *cfs_b = |
| container_of(timer, struct cfs_bandwidth, period_timer); |
| int overrun; |
| int idle = 0; |
| |
| raw_spin_lock(&cfs_b->lock); |
| for (;;) { |
| overrun = hrtimer_forward_now(timer, cfs_b->period); |
| if (!overrun) |
| break; |
| |
| idle = do_sched_cfs_period_timer(cfs_b, overrun); |
| } |
| if (idle) |
| cfs_b->period_active = 0; |
| raw_spin_unlock(&cfs_b->lock); |
| |
| return idle ? HRTIMER_NORESTART : HRTIMER_RESTART; |
| } |
| |
| void init_cfs_bandwidth(struct cfs_bandwidth *cfs_b) |
| { |
| raw_spin_lock_init(&cfs_b->lock); |
| cfs_b->runtime = 0; |
| cfs_b->quota = RUNTIME_INF; |
| cfs_b->period = ns_to_ktime(default_cfs_period()); |
| |
| INIT_LIST_HEAD(&cfs_b->throttled_cfs_rq); |
| hrtimer_init(&cfs_b->period_timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS_PINNED); |
| cfs_b->period_timer.function = sched_cfs_period_timer; |
| hrtimer_init(&cfs_b->slack_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); |
| cfs_b->slack_timer.function = sched_cfs_slack_timer; |
| } |
| |
| static void init_cfs_rq_runtime(struct cfs_rq *cfs_rq) |
| { |
| cfs_rq->runtime_enabled = 0; |
| INIT_LIST_HEAD(&cfs_rq->throttled_list); |
| init_cfs_rq_hmp_stats(cfs_rq); |
| } |
| |
| void start_cfs_bandwidth(struct cfs_bandwidth *cfs_b) |
| { |
| lockdep_assert_held(&cfs_b->lock); |
| |
| if (!cfs_b->period_active) { |
| cfs_b->period_active = 1; |
| hrtimer_forward_now(&cfs_b->period_timer, cfs_b->period); |
| hrtimer_start_expires(&cfs_b->period_timer, HRTIMER_MODE_ABS_PINNED); |
| } |
| } |
| |
| static void destroy_cfs_bandwidth(struct cfs_bandwidth *cfs_b) |
| { |
| /* init_cfs_bandwidth() was not called */ |
| if (!cfs_b->throttled_cfs_rq.next) |
| return; |
| |
| hrtimer_cancel(&cfs_b->period_timer); |
| hrtimer_cancel(&cfs_b->slack_timer); |
| } |
| |
| static void __maybe_unused update_runtime_enabled(struct rq *rq) |
| { |
| struct cfs_rq *cfs_rq; |
| |
| for_each_leaf_cfs_rq(rq, cfs_rq) { |
| struct cfs_bandwidth *cfs_b = &cfs_rq->tg->cfs_bandwidth; |
| |
| raw_spin_lock(&cfs_b->lock); |
| cfs_rq->runtime_enabled = cfs_b->quota != RUNTIME_INF; |
| raw_spin_unlock(&cfs_b->lock); |
| } |
| } |
| |
| static void __maybe_unused unthrottle_offline_cfs_rqs(struct rq *rq) |
| { |
| struct cfs_rq *cfs_rq; |
| |
| for_each_leaf_cfs_rq(rq, cfs_rq) { |
| if (!cfs_rq->runtime_enabled) |
| continue; |
| |
| /* |
| * clock_task is not advancing so we just need to make sure |
| * there's some valid quota amount |
| */ |
| cfs_rq->runtime_remaining = 1; |
| /* |
| * Offline rq is schedulable till cpu is completely disabled |
| * in take_cpu_down(), so we prevent new cfs throttling here. |
| */ |
| cfs_rq->runtime_enabled = 0; |
| |
| if (cfs_rq_throttled(cfs_rq)) |
| unthrottle_cfs_rq(cfs_rq); |
| } |
| } |
| |
| #else /* CONFIG_CFS_BANDWIDTH */ |
| static inline u64 cfs_rq_clock_task(struct cfs_rq *cfs_rq) |
| { |
| return rq_clock_task(rq_of(cfs_rq)); |
| } |
| |
| static void account_cfs_rq_runtime(struct cfs_rq *cfs_rq, u64 delta_exec) {} |
| static bool check_cfs_rq_runtime(struct cfs_rq *cfs_rq) { return false; } |
| static void check_enqueue_throttle(struct cfs_rq *cfs_rq) {} |
| static inline void sync_throttle(struct task_group *tg, int cpu) {} |
| static __always_inline void return_cfs_rq_runtime(struct cfs_rq *cfs_rq) {} |
| |
| static inline int cfs_rq_throttled(struct cfs_rq *cfs_rq) |
| { |
| return 0; |
| } |
| |
| static inline int throttled_hierarchy(struct cfs_rq *cfs_rq) |
| { |
| return 0; |
| } |
| |
| static inline int throttled_lb_pair(struct task_group *tg, |
| int src_cpu, int dest_cpu) |
| { |
| return 0; |
| } |
| |
| void init_cfs_bandwidth(struct cfs_bandwidth *cfs_b) {} |
| |
| #ifdef CONFIG_FAIR_GROUP_SCHED |
| static void init_cfs_rq_runtime(struct cfs_rq *cfs_rq) {} |
| #endif |
| |
| static inline struct cfs_bandwidth *tg_cfs_bandwidth(struct task_group *tg) |
| { |
| return NULL; |
| } |
| static inline void destroy_cfs_bandwidth(struct cfs_bandwidth *cfs_b) {} |
| static inline void update_runtime_enabled(struct rq *rq) {} |
| static inline void unthrottle_offline_cfs_rqs(struct rq *rq) {} |
| |
| #endif /* CONFIG_CFS_BANDWIDTH */ |
| |
| /************************************************** |
| * CFS operations on tasks: |
| */ |
| |
| #ifdef CONFIG_SCHED_HRTICK |
| static void hrtick_start_fair(struct rq *rq, struct task_struct *p) |
| { |
| struct sched_entity *se = &p->se; |
| struct cfs_rq *cfs_rq = cfs_rq_of(se); |
| |
| SCHED_WARN_ON(task_rq(p) != rq); |
| |
| if (rq->cfs.h_nr_running > 1) { |
| u64 slice = sched_slice(cfs_rq, se); |
| u64 ran = se->sum_exec_runtime - se->prev_sum_exec_runtime; |
| s64 delta = slice - ran; |
| |
| if (delta < 0) { |
| if (rq->curr == p) |
| resched_curr(rq); |
| return; |
| } |
| hrtick_start(rq, delta); |
| } |
| } |
| |
| /* |
| * called from enqueue/dequeue and updates the hrtick when the |
| * current task is from our class and nr_running is low enough |
| * to matter. |
| */ |
| static void hrtick_update(struct rq *rq) |
| { |
| struct task_struct *curr = rq->curr; |
| |
| if (!hrtick_enabled(rq) || curr->sched_class != &fair_sched_class) |
| return; |
| |
| if (cfs_rq_of(&curr->se)->nr_running < sched_nr_latency) |
| hrtick_start_fair(rq, curr); |
| } |
| #else /* !CONFIG_SCHED_HRTICK */ |
| static inline void |
| hrtick_start_fair(struct rq *rq, struct task_struct *p) |
| { |
| } |
| |
| static inline void hrtick_update(struct rq *rq) |
| { |
| } |
| #endif |
| |
| #ifdef CONFIG_SMP |
| static bool cpu_overutilized(int cpu); |
| static unsigned long capacity_orig_of(int cpu); |
| static unsigned long cpu_util(int cpu); |
| static inline unsigned long boosted_cpu_util(int cpu); |
| #else |
| #define boosted_cpu_util(cpu) cpu_util(cpu) |
| #endif |
| |
| #ifdef CONFIG_SMP |
| static void update_capacity_of(int cpu) |
| { |
| unsigned long req_cap; |
| |
| if (!sched_freq()) |
| return; |
| |
| /* Convert scale-invariant capacity to cpu. */ |
| req_cap = boosted_cpu_util(cpu); |
| req_cap = req_cap * SCHED_CAPACITY_SCALE / capacity_orig_of(cpu); |
| set_cfs_cpu_capacity(cpu, true, req_cap); |
| } |
| #endif |
| |
| /* |
| * The enqueue_task method is called before nr_running is |
| * increased. Here we update the fair scheduling stats and |
| * then put the task into the rbtree: |
| */ |
| static void |
| enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags) |
| { |
| struct cfs_rq *cfs_rq; |
| struct sched_entity *se = &p->se; |
| #ifdef CONFIG_SMP |
| int task_new = flags & ENQUEUE_WAKEUP_NEW; |
| int task_wakeup = flags & ENQUEUE_WAKEUP; |
| #endif |
| |
| /* |
| * If in_iowait is set, the code below may not trigger any cpufreq |
| * utilization updates, so do it here explicitly with the IOWAIT flag |
| * passed. |
| */ |
| if (p->in_iowait) |
| cpufreq_update_this_cpu(rq, SCHED_CPUFREQ_IOWAIT); |
| |
| for_each_sched_entity(se) { |
| if (se->on_rq) |
| break; |
| cfs_rq = cfs_rq_of(se); |
| enqueue_entity(cfs_rq, se, flags); |
| |
| /* |
| * end evaluation on encountering a throttled cfs_rq |
| * |
| * note: in the case of encountering a throttled cfs_rq we will |
| * post the final h_nr_running increment below. |
| */ |
| if (cfs_rq_throttled(cfs_rq)) |
| break; |
| cfs_rq->h_nr_running++; |
| inc_cfs_rq_hmp_stats(cfs_rq, p, 1); |
| |
| flags = ENQUEUE_WAKEUP; |
| } |
| |
| for_each_sched_entity(se) { |
| cfs_rq = cfs_rq_of(se); |
| cfs_rq->h_nr_running++; |
| inc_cfs_rq_hmp_stats(cfs_rq, p, 1); |
| |
| if (cfs_rq_throttled(cfs_rq)) |
| break; |
| |
| update_load_avg(se, 1); |
| update_cfs_shares(cfs_rq); |
| } |
| |
| if (!se) { |
| add_nr_running(rq, 1); |
| inc_rq_hmp_stats(rq, p, 1); |
| } |
| |
| #ifdef CONFIG_SMP |
| |
| if (!se) { |
| if (!task_new && !rq->rd->overutilized && |
| cpu_overutilized(rq->cpu)) { |
| rq->rd->overutilized = true; |
| trace_sched_overutilized(true); |
| } |
| |
| /* |
| * We want to potentially trigger a freq switch |
| * request only for tasks that are waking up; this is |
| * because we get here also during load balancing, but |
| * in these cases it seems wise to trigger as single |
| * request after load balancing is done. |
| */ |
| if (task_new || task_wakeup) |
| update_capacity_of(cpu_of(rq)); |
| } |
| |
| /* Update SchedTune accouting */ |
| schedtune_enqueue_task(p, cpu_of(rq)); |
| |
| #endif /* CONFIG_SMP */ |
| hrtick_update(rq); |
| } |
| |
| static void set_next_buddy(struct sched_entity *se); |
| |
| /* |
| * The dequeue_task method is called before nr_running is |
| * decreased. We remove the task from the rbtree and |
| * update the fair scheduling stats: |
| */ |
| static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int flags) |
| { |
| struct cfs_rq *cfs_rq; |
| struct sched_entity *se = &p->se; |
| int task_sleep = flags & DEQUEUE_SLEEP; |
| |
| for_each_sched_entity(se) { |
| cfs_rq = cfs_rq_of(se); |
| dequeue_entity(cfs_rq, se, flags); |
| |
| /* |
| * end evaluation on encountering a throttled cfs_rq |
| * |
| * note: in the case of encountering a throttled cfs_rq we will |
| * post the final h_nr_running decrement below. |
| */ |
| if (cfs_rq_throttled(cfs_rq)) |
| break; |
| cfs_rq->h_nr_running--; |
| dec_cfs_rq_hmp_stats(cfs_rq, p, 1); |
| |
| /* Don't dequeue parent if it has other entities besides us */ |
| if (cfs_rq->load.weight) { |
| /* Avoid re-evaluating load for this entity: */ |
| se = parent_entity(se); |
| /* |
| * Bias pick_next to pick a task from this cfs_rq, as |
| * p is sleeping when it is within its sched_slice. |
| */ |
| if (task_sleep && se && !throttled_hierarchy(cfs_rq)) |
| set_next_buddy(se); |
| break; |
| } |
| flags |= DEQUEUE_SLEEP; |
| } |
| |
| for_each_sched_entity(se) { |
| cfs_rq = cfs_rq_of(se); |
| cfs_rq->h_nr_running--; |
| dec_cfs_rq_hmp_stats(cfs_rq, p, 1); |
| |
| if (cfs_rq_throttled(cfs_rq)) |
| break; |
| |
| update_load_avg(se, 1); |
| update_cfs_shares(cfs_rq); |
| } |
| |
| if (!se) { |
| sub_nr_running(rq, 1); |
| dec_rq_hmp_stats(rq, p, 1); |
| } |
| |
| #ifdef CONFIG_SMP |
| |
| if (!se) { |
| /* |
| * We want to potentially trigger a freq switch |
| * request only for tasks that are going to sleep; |
| * this is because we get here also during load |
| * balancing, but in these cases it seems wise to |
| * trigger as single request after load balancing is |
| * done. |
| */ |
| if (task_sleep) { |
| if (rq->cfs.nr_running) |
| update_capacity_of(cpu_of(rq)); |
| else if (sched_freq()) |
| set_cfs_cpu_capacity(cpu_of(rq), false, 0); |
| } |
| } |
| |
| /* Update SchedTune accouting */ |
| schedtune_dequeue_task(p, cpu_of(rq)); |
| |
| #endif /* CONFIG_SMP */ |
| |
| hrtick_update(rq); |
| } |
| |
| #ifdef CONFIG_SMP |
| |
| /* Working cpumask for: load_balance, load_balance_newidle. */ |
| DEFINE_PER_CPU(cpumask_var_t, load_balance_mask); |
| DEFINE_PER_CPU(cpumask_var_t, select_idle_mask); |
| |
| #ifdef CONFIG_NO_HZ_COMMON |
| /* |
| * per rq 'load' arrray crap; XXX kill this. |
| */ |
| |
| /* |
| * The exact cpuload calculated at every tick would be: |
| * |
| * load' = (1 - 1/2^i) * load + (1/2^i) * cur_load |
| * |
| * If a cpu misses updates for n ticks (as it was idle) and update gets |
| * called on the n+1-th tick when cpu may be busy, then we have: |
| * |
| * load_n = (1 - 1/2^i)^n * load_0 |
| * load_n+1 = (1 - 1/2^i) * load_n + (1/2^i) * cur_load |
| * |
| * decay_load_missed() below does efficient calculation of |
| * |
| * load' = (1 - 1/2^i)^n * load |
| * |
| * Because x^(n+m) := x^n * x^m we can decompose any x^n in power-of-2 factors. |
| * This allows us to precompute the above in said factors, thereby allowing the |
| * reduction of an arbitrary n in O(log_2 n) steps. (See also |
| * fixed_power_int()) |
| * |
| * The calculation is approximated on a 128 point scale. |
| */ |
| #define DEGRADE_SHIFT 7 |
| |
| static const u8 degrade_zero_ticks[CPU_LOAD_IDX_MAX] = {0, 8, 32, 64, 128}; |
| static const u8 degrade_factor[CPU_LOAD_IDX_MAX][DEGRADE_SHIFT + 1] = { |
| { 0, 0, 0, 0, 0, 0, 0, 0 }, |
| { 64, 32, 8, 0, 0, 0, 0, 0 }, |
| { 96, 72, 40, 12, 1, 0, 0, 0 }, |
| { 112, 98, 75, 43, 15, 1, 0, 0 }, |
| { 120, 112, 98, 76, 45, 16, 2, 0 } |
| }; |
| |
| /* |
| * Update cpu_load for any missed ticks, due to tickless idle. The backlog |
| * would be when CPU is idle and so we just decay the old load without |
| * adding any new load. |
| */ |
| static unsigned long |
| decay_load_missed(unsigned long load, unsigned long missed_updates, int idx) |
| { |
| int j = 0; |
| |
| if (!missed_updates) |
| return load; |
| |
| if (missed_updates >= degrade_zero_ticks[idx]) |
| return 0; |
| |
| if (idx == 1) |
| return load >> missed_updates; |
| |
| while (missed_updates) { |
| if (missed_updates % 2) |
| load = (load * degrade_factor[idx][j]) >> DEGRADE_SHIFT; |
| |
| missed_updates >>= 1; |
| j++; |
| } |
| return load; |
| } |
| #endif /* CONFIG_NO_HZ_COMMON */ |
| |
| /** |
| * __cpu_load_update - update the rq->cpu_load[] statistics |
| * @this_rq: The rq to update statistics for |
| * @this_load: The current load |
| * @pending_updates: The number of missed updates |
| * |
| * Update rq->cpu_load[] statistics. This function is usually called every |
| * scheduler tick (TICK_NSEC). |
| * |
| * This function computes a decaying average: |
| * |
| * load[i]' = (1 - 1/2^i) * load[i] + (1/2^i) * load |
| * |
| * Because of NOHZ it might not get called on every tick which gives need for |
| * the @pending_updates argument. |
| * |
| * load[i]_n = (1 - 1/2^i) * load[i]_n-1 + (1/2^i) * load_n-1 |
| * = A * load[i]_n-1 + B ; A := (1 - 1/2^i), B := (1/2^i) * load |
| * = A * (A * load[i]_n-2 + B) + B |
| * = A * (A * (A * load[i]_n-3 + B) + B) + B |
| * = A^3 * load[i]_n-3 + (A^2 + A + 1) * B |
| * = A^n * load[i]_0 + (A^(n-1) + A^(n-2) + ... + 1) * B |
| * = A^n * load[i]_0 + ((1 - A^n) / (1 - A)) * B |
| * = (1 - 1/2^i)^n * (load[i]_0 - load) + load |
| * |
| * In the above we've assumed load_n := load, which is true for NOHZ_FULL as |
| * any change in load would have resulted in the tick being turned back on. |
| * |
| * For regular NOHZ, this reduces to: |
| * |
| * load[i]_n = (1 - 1/2^i)^n * load[i]_0 |
| * |
| * see decay_load_misses(). For NOHZ_FULL we get to subtract and add the extra |
| * term. |
| */ |
| static void cpu_load_update(struct rq *this_rq, unsigned long this_load, |
| unsigned long pending_updates) |
| { |
| unsigned long __maybe_unused tickless_load = this_rq->cpu_load[0]; |
| int i, scale; |
| |
| this_rq->nr_load_updates++; |
| |
| /* Update our load: */ |
| this_rq->cpu_load[0] = this_load; /* Fasttrack for idx 0 */ |
| for (i = 1, scale = 2; i < CPU_LOAD_IDX_MAX; i++, scale += scale) { |
| unsigned long old_load, new_load; |
| |
| /* scale is effectively 1 << i now, and >> i divides by scale */ |
| |
| old_load = this_rq->cpu_load[i]; |
| #ifdef CONFIG_NO_HZ_COMMON |
| old_load = decay_load_missed(old_load, pending_updates - 1, i); |
| if (tickless_load) { |
| old_load -= decay_load_missed(tickless_load, pending_updates - 1, i); |
| /* |
| * old_load can never be a negative value because a |
| * decayed tickless_load cannot be greater than the |
| * original tickless_load. |
| */ |
| old_load += tickless_load; |
| } |
| #endif |
| new_load = this_load; |
| /* |
| * Round up the averaging division if load is increasing. This |
| * prevents us from getting stuck on 9 if the load is 10, for |
| * example. |
| */ |
| if (new_load > old_load) |
| new_load += scale - 1; |
| |
| this_rq->cpu_load[i] = (old_load * (scale - 1) + new_load) >> i; |
| } |
| |
| sched_avg_update(this_rq); |
| } |
| |
| /* Used instead of source_load when we know the type == 0 */ |
| static unsigned long weighted_cpuload(const int cpu) |
| { |
| return cfs_rq_runnable_load_avg(&cpu_rq(cpu)->cfs); |
| } |
| |
| #ifdef CONFIG_NO_HZ_COMMON |
| /* |
| * There is no sane way to deal with nohz on smp when using jiffies because the |
| * cpu doing the jiffies update might drift wrt the cpu doing the jiffy reading |
| * causing off-by-one errors in observed deltas; {0,2} instead of {1,1}. |
| * |
| * Therefore we need to avoid the delta approach from the regular tick when |
| * possible since that would seriously skew the load calculation. This is why we |
| * use cpu_load_update_periodic() for CPUs out of nohz. However we'll rely on |
| * jiffies deltas for updates happening while in nohz mode (idle ticks, idle |
| * loop exit, nohz_idle_balance, nohz full exit...) |
| * |
| * This means we might still be one tick off for nohz periods. |
| */ |
| |
| static void cpu_load_update_nohz(struct rq *this_rq, |
| unsigned long curr_jiffies, |
| unsigned long load) |
| { |
| unsigned long pending_updates; |
| |
| pending_updates = curr_jiffies - this_rq->last_load_update_tick; |
| if (pending_updates) { |
| this_rq->last_load_update_tick = curr_jiffies; |
| /* |
| * In the regular NOHZ case, we were idle, this means load 0. |
| * In the NOHZ_FULL case, we were non-idle, we should consider |
| * its weighted load. |
| */ |
| cpu_load_update(this_rq, load, pending_updates); |
| } |
| } |
| |
| /* |
| * Called from nohz_idle_balance() to update the load ratings before doing the |
| * idle balance. |
| */ |
| static void cpu_load_update_idle(struct rq *this_rq) |
| { |
| /* |
| * bail if there's load or we're actually up-to-date. |
| */ |
| if (weighted_cpuload(cpu_of(this_rq))) |
| return; |
| |
| cpu_load_update_nohz(this_rq, READ_ONCE(jiffies), 0); |
| } |
| |
| /* |
| * Record CPU load on nohz entry so we know the tickless load to account |
| * on nohz exit. cpu_load[0] happens then to be updated more frequently |
| * than other cpu_load[idx] but it should be fine as cpu_load readers |
| * shouldn't rely into synchronized cpu_load[*] updates. |
| */ |
| void cpu_load_update_nohz_start(void) |
| { |
| struct rq *this_rq = this_rq(); |
| |
| /* |
| * This is all lockless but should be fine. If weighted_cpuload changes |
| * concurrently we'll exit nohz. And cpu_load write can race with |
| * cpu_load_update_idle() but both updater would be writing the same. |
| */ |
| this_rq->cpu_load[0] = weighted_cpuload(cpu_of(this_rq)); |
| } |
| |
| /* |
| * Account the tickless load in the end of a nohz frame. |
| */ |
| void cpu_load_update_nohz_stop(void) |
| { |
| unsigned long curr_jiffies = READ_ONCE(jiffies); |
| struct rq *this_rq = this_rq(); |
| unsigned long load; |
| |
| if (curr_jiffies == this_rq->last_load_update_tick) |
| return; |
| |
| load = weighted_cpuload(cpu_of(this_rq)); |
| raw_spin_lock(&this_rq->lock); |
| update_rq_clock(this_rq); |
| cpu_load_update_nohz(this_rq, curr_jiffies, load); |
| raw_spin_unlock(&this_rq->lock); |
| } |
| #else /* !CONFIG_NO_HZ_COMMON */ |
| static inline void cpu_load_update_nohz(struct rq *this_rq, |
| unsigned long curr_jiffies, |
| unsigned long load) { } |
| #endif /* CONFIG_NO_HZ_COMMON */ |
| |
| static void cpu_load_update_periodic(struct rq *this_rq, unsigned long load) |
| { |
| #ifdef CONFIG_NO_HZ_COMMON |
| /* See the mess around cpu_load_update_nohz(). */ |
| this_rq->last_load_update_tick = READ_ONCE(jiffies); |
| #endif |
| cpu_load_update(this_rq, load, 1); |
| } |
| |
| /* |
| * Called from scheduler_tick() |
| */ |
| void cpu_load_update_active(struct rq *this_rq) |
| { |
| unsigned long load = weighted_cpuload(cpu_of(this_rq)); |
| |
| if (tick_nohz_tick_stopped()) |
| cpu_load_update_nohz(this_rq, READ_ONCE(jiffies), load); |
| else |
| cpu_load_update_periodic(this_rq, load); |
| } |
| |
| /* |
| * Return a low guess at the load of a migration-source cpu weighted |
| * according to the scheduling class and "nice" value. |
| * |
| * We want to under-estimate the load of migration sources, to |
| * balance conservatively. |
| */ |
| static unsigned long source_load(int cpu, int type) |
| { |
| struct rq *rq = cpu_rq(cpu); |
| unsigned long total = weighted_cpuload(cpu); |
| |
| if (type == 0 || !sched_feat(LB_BIAS)) |
| return total; |
| |
| return min(rq->cpu_load[type-1], total); |
| } |
| |
| /* |
| * Return a high guess at the load of a migration-target cpu weighted |
| * according to the scheduling class and "nice" value. |
| */ |
| static unsigned long target_load(int cpu, int type) |
| { |
| struct rq *rq = cpu_rq(cpu); |
| unsigned long total = weighted_cpuload(cpu); |
| |
| if (type == 0 || !sched_feat(LB_BIAS)) |
| return total; |
| |
| return max(rq->cpu_load[type-1], total); |
| } |
| |
| |
| static unsigned long cpu_avg_load_per_task(int cpu) |
| { |
| struct rq *rq = cpu_rq(cpu); |
| unsigned long nr_running = READ_ONCE(rq->cfs.h_nr_running); |
| unsigned long load_avg = weighted_cpuload(cpu); |
| |
| if (nr_running) |
| return load_avg / nr_running; |
| |
| return 0; |
| } |
| |
| #ifdef CONFIG_FAIR_GROUP_SCHED |
| /* |
| * effective_load() calculates the load change as seen from the root_task_group |
| * |
| * Adding load to a group doesn't make a group heavier, but can cause movement |
| * of group shares between cpus. Assuming the shares were perfectly aligned one |
| * can calculate the shift in shares. |
| * |
| * Calculate the effective load difference if @wl is added (subtracted) to @tg |
| * on this @cpu and results in a total addition (subtraction) of @wg to the |
| * total group weight. |
| * |
| * Given a runqueue weight distribution (rw_i) we can compute a shares |
| * distribution (s_i) using: |
| * |
| * s_i = rw_i / \Sum rw_j (1) |
| * |
| * Suppose we have 4 CPUs and our @tg is a direct child of the root group and |
| * has 7 equal weight tasks, distributed as below (rw_i), with the resulting |
| * shares distribution (s_i): |
| * |
| * rw_i = { 2, 4, 1, 0 } |
| * s_i = { 2/7, 4/7, 1/7, 0 } |
| * |
| * As per wake_affine() we're interested in the load of two CPUs (the CPU the |
| * task used to run on and the CPU the waker is running on), we need to |
| * compute the effect of waking a task on either CPU and, in case of a sync |
| * wakeup, compute the effect of the current task going to sleep. |
| * |
| * So for a change of @wl to the local @cpu with an overall group weight change |
| * of @wl we can compute the new shares distribution (s'_i) using: |
| * |
| * s'_i = (rw_i + @wl) / (@wg + \Sum rw_j) (2) |
| * |
| * Suppose we're interested in CPUs 0 and 1, and want to compute the load |
| * differences in waking a task to CPU 0. The additional task changes the |
| * weight and shares distributions like: |
| * |
| * rw'_i = { 3, 4, 1, 0 } |
| * s'_i = { 3/8, 4/8, 1/8, 0 } |
| * |
| * We can then compute the difference in effective weight by using: |
| * |
| * dw_i = S * (s'_i - s_i) (3) |
| * |
| * Where 'S' is the group weight as seen by its parent. |
| * |
| * Therefore the effective change in loads on CPU 0 would be 5/56 (3/8 - 2/7) |
| * times the weight of the group. The effect on CPU 1 would be -4/56 (4/8 - |
| * 4/7) times the weight of the group. |
| */ |
| static long effective_load(struct task_group *tg, int cpu, long wl, long wg) |
| { |
| struct sched_entity *se = tg->se[cpu]; |
| |
| if (!tg->parent) /* the trivial, non-cgroup case */ |
| return wl; |
| |
| for_each_sched_entity(se) { |
| struct cfs_rq *cfs_rq = se->my_q; |
| long W, w = cfs_rq_load_avg(cfs_rq); |
| |
| tg = cfs_rq->tg; |
| |
| /* |
| * W = @wg + \Sum rw_j |
| */ |
| W = wg + atomic_long_read(&tg->load_avg); |
| |
| /* Ensure \Sum rw_j >= rw_i */ |
| W -= cfs_rq->tg_load_avg_contrib; |
| W += w; |
| |
| /* |
| * w = rw_i + @wl |
| */ |
| w += wl; |
| |
| /* |
| * wl = S * s'_i; see (2) |
| */ |
| if (W > 0 && w < W) |
| wl = (w * (long)scale_load_down(tg->shares)) / W; |
| else |
| wl = scale_load_down(tg->shares); |
| |
| /* |
| * Per the above, wl is the new se->load.weight value; since |
| * those are clipped to [MIN_SHARES, ...) do so now. See |
| * calc_cfs_shares(). |
| */ |
| if (wl < MIN_SHARES) |
| wl = MIN_SHARES; |
| |
| /* |
| * wl = dw_i = S * (s'_i - s_i); see (3) |
| */ |
| wl -= se->avg.load_avg; |
| |
| /* |
| * Recursively apply this logic to all parent groups to compute |
| * the final effective load change on the root group. Since |
| * only the @tg group gets extra weight, all parent groups can |
| * only redistribute existing shares. @wl is the shift in shares |
| * resulting from this level per the above. |
| */ |
| wg = 0; |
| } |
| |
| return wl; |
| } |
| #else |
| |
| static long effective_load(struct task_group *tg, int cpu, long wl, long wg) |
| { |
| return wl; |
| } |
| |
| #endif |
| |
| static void record_wakee(struct task_struct *p) |
| { |
| /* |
| * Only decay a single time; tasks that have less then 1 wakeup per |
| * jiffy will not have built up many flips. |
| */ |
| if (time_after(jiffies, current->wakee_flip_decay_ts + HZ)) { |
| current->wakee_flips >>= 1; |
| current->wakee_flip_decay_ts = jiffies; |
| } |
| |
| if (current->last_wakee != p) { |
| current->last_wakee = p; |
| current->wakee_flips++; |
| } |
| } |
| |
| /* |
| * Returns the current capacity of cpu after applying both |
| * cpu and freq scaling. |
| */ |
| unsigned long capacity_curr_of(int cpu) |
| { |
| return cpu_rq(cpu)->cpu_capacity_orig * |
| arch_scale_freq_capacity(NULL, cpu) |
| >> SCHED_CAPACITY_SHIFT; |
| } |
| |
| static inline bool energy_aware(void) |
| { |
| return sched_feat(ENERGY_AWARE); |
| } |
| |
| /* |
| * Externally visible function. Let's keep the one above |
| * so that the check is inlined/optimized in the sched paths. |
| */ |
| bool sched_is_energy_aware(void) |
| { |
| return energy_aware(); |
| } |
| |
| struct energy_env { |
| struct sched_group *sg_top; |
| struct sched_group *sg_cap; |
| int cap_idx; |
| int util_delta; |
| int src_cpu; |
| int dst_cpu; |
| int energy; |
| int payoff; |
| struct task_struct *task; |
| struct { |
| int before; |
| int after; |
| int delta; |
| int diff; |
| } nrg; |
| struct { |
| int before; |
| int after; |
| int delta; |
| } cap; |
| }; |
| |
| /* |
| * __cpu_norm_util() returns the cpu util relative to a specific capacity, |
| * i.e. it's busy ratio, in the range [0..SCHED_LOAD_SCALE] which is useful for |
| * energy calculations. Using the scale-invariant util returned by |
| * cpu_util() and approximating scale-invariant util by: |
| * |
| * util ~ (curr_freq/max_freq)*1024 * capacity_orig/1024 * running_time/time |
| * |
| * the normalized util can be found using the specific capacity. |
| * |
| * capacity = capacity_orig * curr_freq/max_freq |
| * |
| * norm_util = running_time/time ~ util/capacity |
| */ |
| static unsigned long __cpu_norm_util(int cpu, unsigned long capacity, int delta) |
| { |
| int util = __cpu_util(cpu, delta); |
| |
| if (util >= capacity) |
| return SCHED_CAPACITY_SCALE; |
| |
| return (util << SCHED_CAPACITY_SHIFT)/capacity; |
| } |
| |
| static int calc_util_delta(struct energy_env *eenv, int cpu) |
| { |
| if (cpu == eenv->src_cpu) |
| return -eenv->util_delta; |
| if (cpu == eenv->dst_cpu) |
| return eenv->util_delta; |
| return 0; |
| } |
| |
| static |
| unsigned long group_max_util(struct energy_env *eenv) |
| { |
| int i, delta; |
| unsigned long max_util = 0; |
| |
| for_each_cpu(i, sched_group_cpus(eenv->sg_cap)) { |
| delta = calc_util_delta(eenv, i); |
| max_util = max(max_util, __cpu_util(i, delta)); |
| } |
| |
| return max_util; |
| } |
| |
| /* |
| * group_norm_util() returns the approximated group util relative to it's |
| * current capacity (busy ratio) in the range [0..SCHED_LOAD_SCALE] for use in |
| * energy calculations. Since task executions may or may not overlap in time in |
| * the group the true normalized util is between max(cpu_norm_util(i)) and |
| * sum(cpu_norm_util(i)) when iterating over all cpus in the group, i. The |
| * latter is used as the estimate as it leads to a more pessimistic energy |
| * estimate (more busy). |
| */ |
| static unsigned |
| long group_norm_util(struct energy_env *eenv, struct sched_group *sg) |
| { |
| int i, delta; |
| unsigned long util_sum = 0; |
| unsigned long capacity = sg->sge->cap_states[eenv->cap_idx].cap; |
| |
| for_each_cpu(i, sched_group_cpus(sg)) { |
| delta = calc_util_delta(eenv, i); |
| util_sum += __cpu_norm_util(i, capacity, delta); |
| } |
| |
| if (util_sum > SCHED_CAPACITY_SCALE) |
| return SCHED_CAPACITY_SCALE; |
| return util_sum; |
| } |
| |
| static int find_new_capacity(struct energy_env *eenv, |
| const struct sched_group_energy * const sge) |
| { |
| int idx; |
| unsigned long util = group_max_util(eenv); |
| |
| for (idx = 0; idx < sge->nr_cap_states; idx++) { |
| if (sge->cap_states[idx].cap >= util) |
| break; |
| } |
| |
| eenv->cap_idx = idx; |
| |
| return idx; |
| } |
| |
| static int group_idle_state(struct sched_group *sg) |
| { |
| int i, state = INT_MAX; |
| |
| /* Find the shallowest idle state in the sched group. */ |
| for_each_cpu(i, sched_group_cpus(sg)) |
| state = min(state, idle_get_state_idx(cpu_rq(i))); |
| |
| /* Take non-cpuidle idling into account (active idle/arch_cpu_idle()) */ |
| state++; |
| |
| return state; |
| } |
| |
| /* |
| * sched_group_energy(): Computes the absolute energy consumption of cpus |
| * belonging to the sched_group including shared resources shared only by |
| * members of the group. Iterates over all cpus in the hierarchy below the |
| * sched_group starting from the bottom working it's way up before going to |
| * the next cpu until all cpus are covered at all levels. The current |
| * implementation is likely to gather the same util statistics multiple times. |
| * This can probably be done in a faster but more complex way. |
| * Note: sched_group_energy() may fail when racing with sched_domain updates. |
| */ |
| static int sched_group_energy(struct energy_env *eenv) |
| { |
| struct sched_domain *sd; |
| int cpu, total_energy = 0; |
| struct cpumask visit_cpus; |
| struct sched_group *sg; |
| |
| WARN_ON(!eenv->sg_top->sge); |
| |
| cpumask_copy(&visit_cpus, sched_group_cpus(eenv->sg_top)); |
| |
| while (!cpumask_empty(&visit_cpus)) { |
| struct sched_group *sg_shared_cap = NULL; |
| |
| cpu = cpumask_first(&visit_cpus); |
| |
| /* |
| * Is the group utilization affected by cpus outside this |
| * sched_group? |
| */ |
| sd = rcu_dereference(per_cpu(sd_scs, cpu)); |
| |
| if (!sd) |
| /* |
| * We most probably raced with hotplug; returning a |
| * wrong energy estimation is better than entering an |
| * infinite loop. |
| */ |
| return -EINVAL; |
| |
| if (sd->parent) |
| sg_shared_cap = sd->parent->groups; |
| |
| for_each_domain(cpu, sd) { |
| sg = sd->groups; |
| |
| /* Has this sched_domain already been visited? */ |
| if (sd->child && group_first_cpu(sg) != cpu) |
| break; |
| |
| do { |
| unsigned long group_util; |
| int sg_busy_energy, sg_idle_energy; |
| int cap_idx, idle_idx; |
| |
| if (sg_shared_cap && sg_shared_cap->group_weight >= sg->group_weight) |
| eenv->sg_cap = sg_shared_cap; |
| else |
| eenv->sg_cap = sg; |
| |
| cap_idx = find_new_capacity(eenv, sg->sge); |
| |
| if (sg->group_weight == 1) { |
| /* Remove capacity of src CPU (before task move) */ |
| if (eenv->util_delta == 0 && |
| cpumask_test_cpu(eenv->src_cpu, sched_group_cpus(sg))) { |
| eenv->cap.before = sg->sge->cap_states[cap_idx].cap; |
| eenv->cap.delta -= eenv->cap.before; |
| } |
| /* Add capacity of dst CPU (after task move) */ |
| if (eenv->util_delta != 0 && |
| cpumask_test_cpu(eenv->dst_cpu, sched_group_cpus(sg))) { |
| eenv->cap.after = sg->sge->cap_states[cap_idx].cap; |
| eenv->cap.delta += eenv->cap.after; |
| } |
| } |
| |
| idle_idx = group_idle_state(sg); |
| group_util = group_norm_util(eenv, sg); |
| sg_busy_energy = (group_util * sg->sge->cap_states[cap_idx].power) |
| >> SCHED_CAPACITY_SHIFT; |
| sg_idle_energy = ((SCHED_CAPACITY_SCALE-group_util) |
| * sg->sge->idle_states[idle_idx].power) |
| >> SCHED_CAPACITY_SHIFT; |
| |
| total_energy += sg_busy_energy + sg_idle_energy; |
| |
| if (!sd->child) |
| cpumask_xor(&visit_cpus, &visit_cpus, sched_group_cpus(sg)); |
| |
| if (cpumask_equal(sched_group_cpus(sg), sched_group_cpus(eenv->sg_top))) |
| goto next_cpu; |
| |
| } while (sg = sg->next, sg != sd->groups); |
| } |
| next_cpu: |
| cpumask_clear_cpu(cpu, &visit_cpus); |
| continue; |
| } |
| |
| eenv->energy = total_energy; |
| return 0; |
| } |
| |
| static inline bool cpu_in_sg(struct sched_group *sg, int cpu) |
| { |
| return cpu != -1 && cpumask_test_cpu(cpu, sched_group_cpus(sg)); |
| } |
| |
| /* |
| * energy_diff(): Estimate the energy impact of changing the utilization |
| * distribution. eenv specifies the change: utilisation amount, source, and |
| * destination cpu. Source or destination cpu may be -1 in which case the |
| * utilization is removed from or added to the system (e.g. task wake-up). If |
| * both are specified, the utilization is migrated. |
| */ |
| static inline int __energy_diff(struct energy_env *eenv) |
| { |
| struct sched_domain *sd; |
| struct sched_group *sg; |
| int sd_cpu = -1, energy_before = 0, energy_after = 0; |
| |
| struct energy_env eenv_before = { |
| .util_delta = 0, |
| .src_cpu = eenv->src_cpu, |
| .dst_cpu = eenv->dst_cpu, |
| .nrg = { 0, 0, 0, 0}, |
| .cap = { 0, 0, 0 }, |
| }; |
| |
| if (eenv->src_cpu == eenv->dst_cpu) |
| return 0; |
| |
| sd_cpu = (eenv->src_cpu != -1) ? eenv->src_cpu : eenv->dst_cpu; |
| sd = rcu_dereference(per_cpu(sd_ea, sd_cpu)); |
| |
| if (!sd) |
| return 0; /* Error */ |
| |
| sg = sd->groups; |
| |
| do { |
| if (cpu_in_sg(sg, eenv->src_cpu) || cpu_in_sg(sg, eenv->dst_cpu)) { |
| eenv_before.sg_top = eenv->sg_top = sg; |
| |
| if (sched_group_energy(&eenv_before)) |
| return 0; /* Invalid result abort */ |
| energy_before += eenv_before.energy; |
| |
| /* Keep track of SRC cpu (before) capacity */ |
| eenv->cap.before = eenv_before.cap.before; |
| eenv->cap.delta = eenv_before.cap.delta; |
| |
| if (sched_group_energy(eenv)) |
| return 0; /* Invalid result abort */ |
| energy_after += eenv->energy; |
| } |
| } while (sg = sg->next, sg != sd->groups); |
| |
| eenv->nrg.before = energy_before; |
| eenv->nrg.after = energy_after; |
| eenv->nrg.diff = eenv->nrg.after - eenv->nrg.before; |
| eenv->payoff = 0; |
| |
| trace_sched_energy_diff(eenv->task, |
| eenv->src_cpu, eenv->dst_cpu, eenv->util_delta, |
| eenv->nrg.before, eenv->nrg.after, eenv->nrg.diff, |
| eenv->cap.before, eenv->cap.after, eenv->cap.delta, |
| eenv->nrg.delta, eenv->payoff); |
| |
| return eenv->nrg.diff; |
| } |
| |
| #ifdef CONFIG_SCHED_TUNE |
| |
| struct target_nrg schedtune_target_nrg; |
| |
| /* |
| * System energy normalization |
| * Returns the normalized value, in the range [0..SCHED_LOAD_SCALE], |
| * corresponding to the specified energy variation. |
| */ |
| static inline int |
| normalize_energy(int energy_diff) |
| { |
| u32 normalized_nrg; |
| #ifdef CONFIG_SCHED_DEBUG |
| int max_delta; |
| |
| /* Check for boundaries */ |
| max_delta = schedtune_target_nrg.max_power; |
| max_delta -= schedtune_target_nrg.min_power; |
| WARN_ON(abs(energy_diff) >= max_delta); |
| #endif |
| |
| /* Do scaling using positive numbers to increase the range */ |
| normalized_nrg = (energy_diff < 0) ? -energy_diff : energy_diff; |
| |
| /* Scale by energy magnitude */ |
| normalized_nrg <<= SCHED_CAPACITY_SHIFT; |
| |
| /* Normalize on max energy for target platform */ |
| normalized_nrg = reciprocal_divide( |
| normalized_nrg, schedtune_target_nrg.rdiv); |
| |
| return (energy_diff < 0) ? -normalized_nrg : normalized_nrg; |
| } |
| |
| static inline int |
| energy_diff(struct energy_env *eenv) |
| { |
| unsigned int boost; |
| int nrg_delta; |
| |
| /* Conpute "absolute" energy diff */ |
| __energy_diff(eenv); |
| |
| /* Return energy diff when boost margin is 0 */ |
| #ifdef CONFIG_CGROUP_SCHEDTUNE |
| boost = schedtune_task_boost(eenv->task); |
| #else |
| boost = get_sysctl_sched_cfs_boost(); |
| #endif |
| if (boost == 0) |
| return eenv->nrg.diff; |
| |
| /* Compute normalized energy diff */ |
| nrg_delta = normalize_energy(eenv->nrg.diff); |
| eenv->nrg.delta = nrg_delta; |
| |
| eenv->payoff = schedtune_accept_deltas( |
| eenv->nrg.delta, |
| eenv->cap.delta, |
| eenv->task); |
| |
| /* |
| * When SchedTune is enabled, the energy_diff() function will return |
| * the computed energy payoff value. Since the energy_diff() return |
| * value is expected to be negative by its callers, this evaluation |
| * function return a negative value each time the evaluation return a |
| * positive payoff, which is the condition for the acceptance of |
| * a scheduling decision |
| */ |
| return -eenv->payoff; |
| } |
| #else /* CONFIG_SCHED_TUNE */ |
| #define energy_diff(eenv) __energy_diff(eenv) |
| #endif |
| |
| /* |
| * Detect M:N waker/wakee relationships via a switching-frequency heuristic. |
| * |
| * A waker of many should wake a different task than the one last awakened |
| * at a frequency roughly N times higher than one of its wakees. |
| * |
| * In order to determine whether we should let the load spread vs consolidating |
| * to shared cache, we look for a minimum 'flip' frequency of llc_size in one |
| * partner, and a factor of lls_size higher frequency in the other. |
| * |
| * With both conditions met, we can be relatively sure that the relationship is |
| * non-monogamous, with partner count exceeding socket size. |
| * |
| * Waker/wakee being client/server, worker/dispatcher, interrupt source or |
| * whatever is irrelevant, spread criteria is apparent partner count exceeds |
| * socket size. |
| */ |
| static int wake_wide(struct task_struct *p) |
| { |
| unsigned int master = current->wakee_flips; |
| unsigned int slave = p->wakee_flips; |
| int factor = this_cpu_read(sd_llc_size); |
| |
| if (master < slave) |
| swap(master, slave); |
| if (slave < factor || master < slave * factor) |
| return 0; |
| return 1; |
| } |
| |
| static int wake_affine(struct sched_domain *sd, struct task_struct *p, |
| int prev_cpu, int sync) |
| { |
| s64 this_load, load; |
| s64 this_eff_load, prev_eff_load; |
| int idx, this_cpu; |
| struct task_group *tg; |
| unsigned long weight; |
| int balanced; |
| |
| idx = sd->wake_idx; |
| this_cpu = smp_processor_id(); |
| load = source_load(prev_cpu, idx); |
| this_load = target_load(this_cpu, idx); |
| |
| /* |
| * If sync wakeup then subtract the (maximum possible) |
| * effect of the currently running task from the load |
| * of the current CPU: |
| */ |
| if (sync) { |
| tg = task_group(current); |
| weight = current->se.avg.load_avg; |
| |
| this_load += effective_load(tg, this_cpu, -weight, -weight); |
| load += effective_load(tg, prev_cpu, 0, -weight); |
| } |
| |
| tg = task_group(p); |
| weight = p->se.avg.load_avg; |
| |
| /* |
| * In low-load situations, where prev_cpu is idle and this_cpu is idle |
| * due to the sync cause above having dropped this_load to 0, we'll |
| * always have an imbalance, but there's really nothing you can do |
| * about that, so that's good too. |
| * |
| * Otherwise check if either cpus are near enough in load to allow this |
| * task to be woken on this_cpu. |
| */ |
| this_eff_load = 100; |
| this_eff_load *= capacity_of(prev_cpu); |
| |
| prev_eff_load = 100 + (sd->imbalance_pct - 100) / 2; |
| prev_eff_load *= capacity_of(this_cpu); |
| |
| if (this_load > 0) { |
| this_eff_load *= this_load + |
| effective_load(tg, this_cpu, weight, weight); |
| |
| prev_eff_load *= load + effective_load(tg, prev_cpu, 0, weight); |
| } |
| |
| balanced = this_eff_load <= prev_eff_load; |
| |
| schedstat_inc(p->se.statistics.nr_wakeups_affine_attempts); |
| |
| if (!balanced) |
| return 0; |
| |
| schedstat_inc(sd->ttwu_move_affine); |
| schedstat_inc(p->se.statistics.nr_wakeups_affine); |
| |
| return 1; |
| } |
| |
| static inline int task_util(struct task_struct *p) |
| { |
| #ifdef CONFIG_SCHED_WALT |
| if (!walt_disabled && sysctl_sched_use_walt_task_util) { |
| unsigned long demand = p->ravg.demand; |
| return (demand << 10) / walt_ravg_window; |
| } |
| #endif |
| return p->se.avg.util_avg; |
| } |
| |
| static inline unsigned long boosted_task_util(struct task_struct *task); |
| |
| static inline bool __task_fits(struct task_struct *p, int cpu, int util) |
| { |
| unsigned long capacity = capacity_of(cpu); |
| |
| util += boosted_task_util(p); |
| |
| return (capacity * 1024) > (util * capacity_margin); |
| } |
| |
| static inline bool task_fits_max(struct task_struct *p, int cpu) |
| { |
| unsigned long capacity = capacity_of(cpu); |
| unsigned long max_capacity = cpu_rq(cpu)->rd->max_cpu_capacity.val; |
| |
| if (capacity == max_capacity) |
| return true; |
| |
| if (capacity * capacity_margin > max_capacity * 1024) |
| return true; |
| |
| return __task_fits(p, cpu, 0); |
| } |
| |
| static inline bool task_fits_spare(struct task_struct *p, int cpu) |
| { |
| return __task_fits(p, cpu, cpu_util(cpu)); |
| } |
| |
| static bool cpu_overutilized(int cpu) |
| { |
| return (capacity_of(cpu) * 1024) < (cpu_util(cpu) * capacity_margin); |
| } |
| |
| #ifdef CONFIG_SCHED_TUNE |
| |
| static long |
| schedtune_margin(unsigned long signal, long boost) |
| { |
| long long margin = 0; |
| |
| /* |
| * Signal proportional compensation (SPC) |
| * |
| * The Boost (B) value is used to compute a Margin (M) which is |
| * proportional to the complement of the original Signal (S): |
| * M = B * (SCHED_LOAD_SCALE - S), if B is positive |
| * M = B * S, if B is negative |
| * The obtained M could be used by the caller to "boost" S. |
| */ |
| |
| if (boost >= 0) { |
| margin = SCHED_CAPACITY_SCALE - signal; |
| margin *= boost; |
| } else |
| margin = -signal * boost; |
| /* |
| * Fast integer division by constant: |
| * Constant : (C) = 100 |
| * Precision : 0.1% (P) = 0.1 |
| * Reference : C * 100 / P (R) = 100000 |
| * |
| * Thus: |
| * Shift bits : ceil(log(R,2)) (S) = 17 |
| * Mult const : round(2^S/C) (M) = 1311 |
| * |
| * |
| */ |
| margin *= 1311; |
| margin >>= 17; |
| |
| if (boost < 0) |
| margin *= -1; |
| return margin; |
| } |
| |
| static inline int |
| schedtune_cpu_margin(unsigned long util, int cpu) |
| { |
| int boost; |
| |
| #ifdef CONFIG_CGROUP_SCHEDTUNE |
| boost = schedtune_cpu_boost(cpu); |
| #else |
| boost = get_sysctl_sched_cfs_boost(); |
| #endif |
| if (boost == 0) |
| return 0; |
| |
| return schedtune_margin(util, boost); |
| } |
| |
| static inline long |
| schedtune_task_margin(struct task_struct *task) |
| { |
| int boost; |
| unsigned long util; |
| long margin; |
| |
| #ifdef CONFIG_CGROUP_SCHEDTUNE |
| boost = schedtune_task_boost(task); |
| #else |
| boost = get_sysctl_sched_cfs_boost(); |
| #endif |
| if (boost == 0) |
| return 0; |
| |
| util = task_util(task); |
| margin = schedtune_margin(util, boost); |
| |
| return margin; |
| } |
| |
| #else /* CONFIG_SCHED_TUNE */ |
| |
| static inline int |
| schedtune_cpu_margin(unsigned long util, int cpu) |
| { |
| return 0; |
| } |
| |
| static inline int |
| schedtune_task_margin(struct task_struct *task) |
| { |
| return 0; |
| } |
| |
| #endif /* CONFIG_SCHED_TUNE */ |
| |
| static inline unsigned long |
| boosted_cpu_util(int cpu) |
| { |
| unsigned long util = cpu_util(cpu); |
| long margin = schedtune_cpu_margin(util, cpu); |
| |
| trace_sched_boost_cpu(cpu, util, margin); |
| |
| return util + margin; |
| } |
| |
| static inline unsigned long |
| boosted_task_util(struct task_struct *task) |
| { |
| unsigned long util = task_util(task); |
| long margin = schedtune_task_margin(task); |
| |
| trace_sched_boost_task(task, util, margin); |
| |
| return util + margin; |
| } |
| |
| /* |
| * find_idlest_group finds and returns the least busy CPU group within the |
| * domain. |
| */ |
| static struct sched_group * |
| find_idlest_group(struct sched_domain *sd, struct task_struct *p, |
| int this_cpu, int sd_flag) |
| { |
| struct sched_group *idlest = NULL, *group = sd->groups; |
| struct sched_group *fit_group = NULL, *spare_group = NULL; |
| unsigned long min_load = ULONG_MAX, this_load = 0; |
| unsigned long fit_capacity = ULONG_MAX; |
| unsigned long max_spare_capacity = capacity_margin - SCHED_CAPACITY_SCALE; |
| int load_idx = sd->forkexec_idx; |
| int imbalance = 100 + (sd->imbalance_pct-100)/2; |
| |
| if (sd_flag & SD_BALANCE_WAKE) |
| load_idx = sd->wake_idx; |
| |
| do { |
| unsigned long load, avg_load, spare_capacity; |
| int local_group; |
| int i; |
| |
| /* Skip over this group if it has no CPUs allowed */ |
| if (!cpumask_intersects(sched_group_cpus(group), |
| tsk_cpus_allowed(p))) |
| continue; |
| |
| local_group = cpumask_test_cpu(this_cpu, |
| sched_group_cpus(group)); |
| |
| /* Tally up the load of all CPUs in the group */ |
| avg_load = 0; |
| |
| for_each_cpu(i, sched_group_cpus(group)) { |
| /* Bias balancing toward cpus of our domain */ |
| if (local_group) |
| load = source_load(i, load_idx); |
| else |
| load = target_load(i, load_idx); |
| |
| avg_load += load; |
| |
| /* |
| * Look for most energy-efficient group that can fit |
| * that can fit the task. |
| */ |
| if (capacity_of(i) < fit_capacity && task_fits_spare(p, i)) { |
| fit_capacity = capacity_of(i); |
| fit_group = group; |
| } |
| |
| /* |
| * Look for group which has most spare capacity on a |
| * single cpu. |
| */ |
| spare_capacity = capacity_of(i) - cpu_util(i); |
| if (spare_capacity > max_spare_capacity) { |
| max_spare_capacity = spare_capacity; |
| spare_group = group; |
| } |
| } |
| |
| /* Adjust by relative CPU capacity of the group */ |
| avg_load = (avg_load * SCHED_CAPACITY_SCALE) / group->sgc->capacity; |
| |
| if (local_group) { |
| this_load = avg_load; |
| } else if (avg_load < min_load) { |
| min_load = avg_load; |
| idlest = group; |
| } |
| } while (group = group->next, group != sd->groups); |
| |
| if (fit_group) |
| return fit_group; |
| |
| if (spare_group) |
| return spare_group; |
| |
| if (!idlest || 100*this_load < imbalance*min_load) |
| return NULL; |
| return idlest; |
| } |
| |
| /* |
| * find_idlest_cpu - find the idlest cpu among the cpus in group. |
| */ |
| static int |
| find_idlest_cpu(struct sched_group *group, struct task_struct *p, int this_cpu) |
| { |
| unsigned long load, min_load = ULONG_MAX; |
| unsigned int min_exit_latency = UINT_MAX; |
| u64 latest_idle_timestamp = 0; |
| int least_loaded_cpu = this_cpu; |
| int shallowest_idle_cpu = -1; |
| int i; |
| |
| /* Check if we have any choice: */ |
| if (group->group_weight == 1) |
| return cpumask_first(sched_group_cpus(group)); |
| |
| /* Traverse only the allowed CPUs */ |
| for_each_cpu_and(i, sched_group_cpus(group), tsk_cpus_allowed(p)) { |
| if (task_fits_spare(p, i)) { |
| struct rq *rq = cpu_rq(i); |
| struct cpuidle_state *idle = idle_get_state(rq); |
| if (idle && idle->exit_latency < min_exit_latency) { |
| /* |
| * We give priority to a CPU whose idle state |
| * has the smallest exit latency irrespective |
| * of any idle timestamp. |
| */ |
| min_exit_latency = idle->exit_latency; |
| latest_idle_timestamp = rq->idle_stamp; |
| shallowest_idle_cpu = i; |
| } else if (idle_cpu(i) && |
| (!idle || idle->exit_latency == min_exit_latency) && |
| rq->idle_stamp > latest_idle_timestamp) { |
| /* |
| * If equal or no active idle state, then |
| * the most recently idled CPU might have |
| * a warmer cache. |
| */ |
| latest_idle_timestamp = rq->idle_stamp; |
| shallowest_idle_cpu = i; |
| } else if (shallowest_idle_cpu == -1) { |
| /* |
| * If we haven't found an idle CPU yet |
| * pick a non-idle one that can fit the task as |
| * fallback. |
| */ |
| shallowest_idle_cpu = i; |
| } |
| } else if (shallowest_idle_cpu == -1) { |
| load = weighted_cpuload(i); |
| if (load < min_load || (load == min_load && i == this_cpu)) { |
| min_load = load; |
| least_loaded_cpu = i; |
| } |
| } |
| } |
| |
| return shallowest_idle_cpu != -1 ? shallowest_idle_cpu : least_loaded_cpu; |
| } |
| |
| /* |
| * Implement a for_each_cpu() variant that starts the scan at a given cpu |
| * (@start), and wraps around. |
| * |
| * This is used to scan for idle CPUs; such that not all CPUs looking for an |
| * idle CPU find the same CPU. The down-side is that tasks tend to cycle |
| * through the LLC domain. |
| * |
| * Especially tbench is found sensitive to this. |
| */ |
| |
| static int cpumask_next_wrap(int n, const struct cpumask *mask, int start, int *wrapped) |
| { |
| int next; |
| |
| again: |
| next = find_next_bit(cpumask_bits(mask), nr_cpumask_bits, n+1); |
| |
| if (*wrapped) { |
| if (next >= start) |
| return nr_cpumask_bits; |
| } else { |
| if (next >= nr_cpumask_bits) { |
| *wrapped = 1; |
| n = -1; |
| goto again; |
| } |
| } |
| |
| return next; |
| } |
| |
| #define for_each_cpu_wrap(cpu, mask, start, wrap) \ |
| for ((wrap) = 0, (cpu) = (start)-1; \ |
| (cpu) = cpumask_next_wrap((cpu), (mask), (start), &(wrap)), \ |
| (cpu) < nr_cpumask_bits; ) |
| |
| #ifdef CONFIG_SCHED_SMT |
| |
| static inline void set_idle_cores(int cpu, int val) |
| { |
| struct sched_domain_shared *sds; |
| |
| sds = rcu_dereference(per_cpu(sd_llc_shared, cpu)); |
| if (sds) |
| WRITE_ONCE(sds->has_idle_cores, val); |
| } |
| |
| static inline bool test_idle_cores(int cpu, bool def) |
| { |
| struct sched_domain_shared *sds; |
| |
| sds = rcu_dereference(per_cpu(sd_llc_shared, cpu)); |
| if (sds) |
| return READ_ONCE(sds->has_idle_cores); |
| |
| return def; |
| } |
| |
| /* |
| * Scans the local SMT mask to see if the entire core is idle, and records this |
| * information in sd_llc_shared->has_idle_cores. |
| * |
| * Since SMT siblings share all cache levels, inspecting this limited remote |
| * state should be fairly cheap. |
| */ |
| void __update_idle_core(struct rq *rq) |
| { |
| int core = cpu_of(rq); |
| int cpu; |
| |
| rcu_read_lock(); |
| if (test_idle_cores(core, true)) |
| goto unlock; |
| |
| for_each_cpu(cpu, cpu_smt_mask(core)) { |
| if (cpu == core) |
| continue; |
| |
| if (!idle_cpu(cpu)) |
| goto unlock; |
| } |
| |
| set_idle_cores(core, 1); |
| unlock: |
| rcu_read_unlock(); |
| } |
| |
| /* |
| * Scan the entire LLC domain for idle cores; this dynamically switches off if |
| * there are no idle cores left in the system; tracked through |
| * sd_llc->shared->has_idle_cores and enabled through update_idle_core() above. |
| */ |
| static int select_idle_core(struct task_struct *p, struct sched_domain *sd, int target) |
| { |
| struct cpumask *cpus = this_cpu_cpumask_var_ptr(select_idle_mask); |
| int core, cpu, wrap; |
| |
| if (!static_branch_likely(&sched_smt_present)) |
| return -1; |
| |
| if (!test_idle_cores(target, false)) |
| return -1; |
| |
| cpumask_and(cpus, sched_domain_span(sd), tsk_cpus_allowed(p)); |
| |
| for_each_cpu_wrap(core, cpus, target, wrap) { |
| bool idle = true; |
| |
| for_each_cpu(cpu, cpu_smt_mask(core)) { |
| cpumask_clear_cpu(cpu, cpus); |
| if (!idle_cpu(cpu)) |
| idle = false; |
| } |
| |
| if (idle) |
| return core; |
| } |
| |
| /* |
| * Failed to find an idle core; stop looking for one. |
| */ |
| set_idle_cores(target, 0); |
| |
| return -1; |
| } |
| |
| /* |
| * Scan the local SMT mask for idle CPUs. |
| */ |
| static int select_idle_smt(struct task_struct *p, struct sched_domain *sd, int target) |
| { |
| int cpu; |
| |
| if (!static_branch_likely(&sched_smt_present)) |
| return -1; |
| |
| for_each_cpu(cpu, cpu_smt_mask(target)) { |
| if (!cpumask_test_cpu(cpu, tsk_cpus_allowed(p))) |
| continue; |
| if (idle_cpu(cpu)) |
| return cpu; |
| } |
| |
| return -1; |
| } |
| |
| #else /* CONFIG_SCHED_SMT */ |
| |
| static inline int select_idle_core(struct task_struct *p, struct sched_domain *sd, int target) |
| { |
| return -1; |
| } |
| |
| static inline int select_idle_smt(struct task_struct *p, struct sched_domain *sd, int target) |
| { |
| return -1; |
| } |
| |
| #endif /* CONFIG_SCHED_SMT */ |
| |
| /* |
| * Scan the LLC domain for idle CPUs; this is dynamically regulated by |
| * comparing the average scan cost (tracked in sd->avg_scan_cost) against the |
| * average idle time for this rq (as found in rq->avg_idle). |
| */ |
| static int select_idle_cpu(struct task_struct *p, struct sched_domain *sd, int target) |
| { |
| struct sched_domain *this_sd; |
| u64 avg_cost, avg_idle = this_rq()->avg_idle; |
| u64 time, cost; |
| s64 delta; |
| int cpu, wrap; |
| |
| this_sd = rcu_dereference(*this_cpu_ptr(&sd_llc)); |
| if (!this_sd) |
| return -1; |
| |
| avg_cost = this_sd->avg_scan_cost; |
| |
| /* |
| * Due to large variance we need a large fuzz factor; hackbench in |
| * particularly is sensitive here. |
| */ |
| if ((avg_idle / 512) < avg_cost) |
| return -1; |
| |
| time = local_clock(); |
| |
| for_each_cpu_wrap(cpu, sched_domain_span(sd), target, wrap) { |
| if (!cpumask_test_cpu(cpu, tsk_cpus_allowed(p))) |
| continue; |
| if (idle_cpu(cpu)) |
| break; |
| } |
| |
| time = local_clock() - time; |
| cost = this_sd->avg_scan_cost; |
| delta = (s64)(time - cost) / 8; |
| this_sd->avg_scan_cost += delta; |
| |
| return cpu; |
| } |
| |
| /* |
| * Try and locate an idle core/thread in the LLC cache domain. |
| */ |
| static int select_idle_sibling(struct task_struct *p, int prev, int target) |
| { |
| struct sched_domain *sd; |
| struct sched_group *sg; |
| int i = task_cpu(p); |
| int best_idle = -1; |
| int best_idle_cstate = -1; |
| int best_idle_capacity = INT_MAX; |
| |
| if (!sysctl_sched_cstate_aware) { |
| if (idle_cpu(target)) |
| return target; |
| |
| /* |
| * If the prevous cpu is cache affine and idle, don't be stupid. |
| */ |
| if (i != target && cpus_share_cache(i, target) && idle_cpu(i)) |
| return i; |
| |
| sd = rcu_dereference(per_cpu(sd_llc, target)); |
| if (!sd) |
| return target; |
| |
| i = select_idle_core(p, sd, target); |
| if ((unsigned)i < nr_cpumask_bits) |
| return i; |
| |
| i = select_idle_cpu(p, sd, target); |
| if ((unsigned)i < nr_cpumask_bits) |
| return i; |
| |
| i = select_idle_smt(p, sd, target); |
| if ((unsigned)i < nr_cpumask_bits) |
| return i; |
| } |
| |
| /* |
| * Otherwise, iterate the domains and find an elegible idle cpu. |
| */ |
| sd = rcu_dereference(per_cpu(sd_llc, target)); |
| for_each_lower_domain(sd) { |
| sg = sd->groups; |
| do { |
| if (!cpumask_intersects(sched_group_cpus(sg), |
| tsk_cpus_allowed(p))) |
| goto next; |
| |
| |
| if (sysctl_sched_cstate_aware) { |
| for_each_cpu_and(i, tsk_cpus_allowed(p), sched_group_cpus(sg)) { |
| struct rq *rq = cpu_rq(i); |
| int idle_idx = idle_get_state_idx(rq); |
| unsigned long new_usage = boosted_task_util(p); |
| unsigned long capacity_orig = capacity_orig_of(i); |
| if (new_usage > capacity_orig || !idle_cpu(i)) |
| goto next; |
| |
| if (i == target && new_usage <= capacity_curr_of(target)) |
| return target; |
| |
| if (best_idle < 0 || (idle_idx < best_idle_cstate && capacity_orig <= best_idle_capacity)) { |
| best_idle = i; |
| best_idle_cstate = idle_idx; |
| best_idle_capacity = capacity_orig; |
| } |
| } |
| } else { |
| for_each_cpu(i, sched_group_cpus(sg)) { |
| if (i == target || !idle_cpu(i)) |
| goto next; |
| } |
| |
| target = cpumask_first_and(sched_group_cpus(sg), |
| tsk_cpus_allowed(p)); |
| goto done; |
| } |
| next: |
| sg = sg->next; |
| } while (sg != sd->groups); |
| } |
| if (best_idle > 0) |
| target = best_idle; |
| |
| done: |
| return target; |
| } |
| |
| static inline int find_best_target(struct task_struct *p, bool boosted, bool prefer_idle) |
| { |
| int iter_cpu; |
| int target_cpu = -1; |
| int target_util = 0; |
| int backup_capacity = 0; |
| int best_idle_cpu = -1; |
| int best_idle_cstate = INT_MAX; |
| int backup_cpu = -1; |
| unsigned long task_util_boosted, new_util; |
| |
| task_util_boosted = boosted_task_util(p); |
| for (iter_cpu = 0; iter_cpu < NR_CPUS; iter_cpu++) { |
| int cur_capacity; |
| struct rq *rq; |
| int idle_idx; |
| |
| /* |
| * Iterate from higher cpus for boosted tasks. |
| */ |
| int i = boosted ? NR_CPUS-iter_cpu-1 : iter_cpu; |
| |
| if (!cpu_online(i) || !cpumask_test_cpu(i, tsk_cpus_allowed(p))) |
| continue; |
| |
| /* |
| * p's blocked utilization is still accounted for on prev_cpu |
| * so prev_cpu will receive a negative bias due to the double |
| * accounting. However, the blocked utilization may be zero. |
| */ |
| new_util = cpu_util(i) + task_util_boosted; |
| |
| /* |
| * Ensure minimum capacity to grant the required boost. |
| * The target CPU can be already at a capacity level higher |
| * than the one required to boost the task. |
| */ |
| if (new_util > capacity_orig_of(i)) |
| continue; |
| |
| #ifdef CONFIG_SCHED_WALT |
| if (walt_cpu_high_irqload(i)) |
| continue; |
| #endif |
| /* |
| * Unconditionally favoring tasks that prefer idle cpus to |
| * improve latency. |
| */ |
| if (idle_cpu(i) && prefer_idle) { |
| if (best_idle_cpu < 0) |
| best_idle_cpu = i; |
| continue; |
| } |
| |
| cur_capacity = capacity_curr_of(i); |
| rq = cpu_rq(i); |
| idle_idx = idle_get_state_idx(rq); |
| |
| if (new_util < cur_capacity) { |
| if (cpu_rq(i)->nr_running) { |
| if(prefer_idle) { |
| // Find a target cpu with lowest |
| // utilization. |
| if (target_util == 0 || |
| target_util < new_util) { |
| target_cpu = i; |
| target_util = new_util; |
| } |
| } else { |
| // Find a target cpu with highest |
| // utilization. |
| if (target_util == 0 || |
| target_util > new_util) { |
| target_cpu = i; |
| target_util = new_util; |
| } |
| } |
| } else if (!prefer_idle) { |
| if (best_idle_cpu < 0 || |
| (sysctl_sched_cstate_aware && |
| best_idle_cstate > idle_idx)) { |
| best_idle_cstate = idle_idx; |
| best_idle_cpu = i; |
| } |
| } |
| } else if (backup_capacity == 0 || |
| backup_capacity > cur_capacity) { |
| // Find a backup cpu with least capacity. |
| backup_capacity = cur_capacity; |
| backup_cpu = i; |
| } |
| } |
| |
| if (prefer_idle && best_idle_cpu >= 0) |
| target_cpu = best_idle_cpu; |
| else if (target_cpu < 0) |
| target_cpu = best_idle_cpu >= 0 ? best_idle_cpu : backup_cpu; |
| |
| return target_cpu; |
| } |
| |
| static int energy_aware_wake_cpu(struct task_struct *p, int target, int sync) |
| { |
| struct sched_domain *sd; |
| struct sched_group *sg, *sg_target; |
| int target_max_cap = INT_MAX; |
| int target_cpu = task_cpu(p); |
| unsigned long task_util_boosted, new_util; |
| int i; |
| |
| if (sysctl_sched_sync_hint_enable && sync) { |
| int cpu = smp_processor_id(); |
| cpumask_t search_cpus; |
| cpumask_and(&search_cpus, tsk_cpus_allowed(p), cpu_online_mask); |
| if (cpumask_test_cpu(cpu, &search_cpus)) |
| return cpu; |
| } |
| |
| sd = rcu_dereference(per_cpu(sd_ea, task_cpu(p))); |
| |
| if (!sd) |
| return target; |
| |
| sg = sd->groups; |
| sg_target = sg; |
| |
| if (sysctl_sched_is_big_little) { |
| |
| /* |
| * Find group with sufficient capacity. We only get here if no cpu is |
| * overutilized. We may end up overutilizing a cpu by adding the task, |
| * but that should not be any worse than select_idle_sibling(). |
| * load_balance() should sort it out later as we get above the tipping |
| * point. |
| */ |
| do { |
| /* Assuming all cpus are the same in group */ |
| int max_cap_cpu = group_first_cpu(sg); |
| |
| /* |
| * Assume smaller max capacity means more energy-efficient. |
| * Ideally we should query the energy model for the right |
| * answer but it easily ends up in an exhaustive search. |
| */ |
| if (capacity_of(max_cap_cpu) < target_max_cap && |
| task_fits_max(p, max_cap_cpu)) { |
| sg_target = sg; |
| target_max_cap = capacity_of(max_cap_cpu); |
| } |
| } while (sg = sg->next, sg != sd->groups); |
| |
| task_util_boosted = boosted_task_util(p); |
| /* Find cpu with sufficient capacity */ |
| for_each_cpu_and(i, tsk_cpus_allowed(p), sched_group_cpus(sg_target)) { |
| /* |
| * p's blocked utilization is still accounted for on prev_cpu |
| * so prev_cpu will receive a negative bias due to the double |
| * accounting. However, the blocked utilization may be zero. |
| */ |
| new_util = cpu_util(i) + task_util_boosted; |
| |
| /* |
| * Ensure minimum capacity to grant the required boost. |
| * The target CPU can be already at a capacity level higher |
| * than the one required to boost the task. |
| */ |
| if (new_util > capacity_orig_of(i)) |
| continue; |
| |
| if (new_util < capacity_curr_of(i)) { |
| target_cpu = i; |
| if (cpu_rq(i)->nr_running) |
| break; |
| } |
| |
| /* cpu has capacity at higher OPP, keep it as fallback */ |
| if (target_cpu == task_cpu(p)) |
| target_cpu = i; |
| } |
| } else { |
| /* |
| * Find a cpu with sufficient capacity |
| */ |
| #ifdef CONFIG_CGROUP_SCHEDTUNE |
| bool boosted = schedtune_task_boost(p) > 0; |
| bool prefer_idle = schedtune_prefer_idle(p) > 0; |
| #else |
| bool boosted = 0; |
| bool prefer_idle = 0; |
| #endif |
| int tmp_target = find_best_target(p, boosted, prefer_idle); |
| if (tmp_target >= 0) { |
| target_cpu = tmp_target; |
| if ((boosted || prefer_idle) && idle_cpu(target_cpu)) |
| return target_cpu; |
| } |
| } |
| |
| if (target_cpu != task_cpu(p)) { |
| struct energy_env eenv = { |
| .util_delta = task_util(p), |
| .src_cpu = task_cpu(p), |
| .dst_cpu = target_cpu, |
| .task = p, |
| }; |
| |
| /* Not enough spare capacity on previous cpu */ |
| if (cpu_overutilized(task_cpu(p))) |
| return target_cpu; |
| |
| if (energy_diff(&eenv) >= 0) |
| return task_cpu(p); |
| } |
| |
| return target_cpu; |
| } |
| |
| /* |
| * select_task_rq_fair: Select target runqueue for the waking task in domains |
| * that have the 'sd_flag' flag set. In practice, this is SD_BALANCE_WAKE, |
| * SD_BALANCE_FORK, or SD_BALANCE_EXEC. |
| * |
| * Balances load by selecting the idlest cpu in the idlest group, or under |
| * certain conditions an idle sibling cpu if the domain has SD_WAKE_AFFINE set. |
| * |
| * Returns the target cpu number. |
| * |
| * preempt must be disabled. |
| */ |
| static int |
| select_task_rq_fair(struct task_struct *p, int prev_cpu, int sd_flag, int wake_flags) |
| { |
| struct sched_domain *tmp, *affine_sd = NULL, *sd = NULL; |
| int cpu = smp_processor_id(); |
| int new_cpu = prev_cpu; |
| int want_affine = 0; |
| int sync = wake_flags & WF_SYNC; |
| |
| #ifdef CONFIG_SCHED_HMP |
| return select_best_cpu(p, prev_cpu, 0, sync); |
| #endif |
| |
| if (sd_flag & SD_BALANCE_WAKE) { |
| record_wakee(p); |
| want_affine = (!wake_wide(p) && task_fits_max(p, cpu) && |
| cpumask_test_cpu(cpu, tsk_cpus_allowed(p))) || |
| energy_aware(); |
| } |
| |
| rcu_read_lock(); |
| for_each_domain(cpu, tmp) { |
| if (!(tmp->flags & SD_LOAD_BALANCE)) |
| break; |
| |
| /* |
| * If both cpu and prev_cpu are part of this domain, |
| * cpu is a valid SD_WAKE_AFFINE target. |
| */ |
| if (want_affine && (tmp->flags & SD_WAKE_AFFINE) && |
| cpumask_test_cpu(prev_cpu, sched_domain_span(tmp))) { |
| affine_sd = tmp; |
| break; |
| } |
| |
| if (tmp->flags & sd_flag) |
| sd = tmp; |
| else if (!want_affine) |
| break; |
| } |
| |
| if (affine_sd) { |
| sd = NULL; /* Prefer wake_affine over balance flags */ |
| if (cpu != prev_cpu && wake_affine(affine_sd, p, prev_cpu, sync)) |
| new_cpu = cpu; |
| } |
| |
| if (!sd) { |
| if (energy_aware() && !cpu_rq(cpu)->rd->overutilized) |
| new_cpu = energy_aware_wake_cpu(p, prev_cpu, sync); |
| else if (sd_flag & SD_BALANCE_WAKE) /* XXX always ? */ |
| new_cpu = select_idle_sibling(p, prev_cpu, new_cpu); |
| |
| } else while (sd) { |
| struct sched_group *group; |
| int weight; |
| |
| if (!(sd->flags & sd_flag)) { |
| sd = sd->child; |
| continue; |
| } |
| |
| group = find_idlest_group(sd, p, cpu, sd_flag); |
| if (!group) { |
| sd = sd->child; |
| continue; |
| } |
| |
| new_cpu = find_idlest_cpu(group, p, cpu); |
| if (new_cpu == -1 || new_cpu == cpu) { |
| /* Now try balancing at a lower domain level of cpu */ |
| sd = sd->child; |
| continue; |
| } |
| |
| /* Now try balancing at a lower domain level of new_cpu */ |
| cpu = new_cpu; |
| weight = sd->span_weight; |
| sd = NULL; |
| for_each_domain(cpu, tmp) { |
| if (weight <= tmp->span_weight) |
| break; |
| if (tmp->flags & sd_flag) |
| sd = tmp; |
| } |
| /* while loop will break here if sd == NULL */ |
| } |
| rcu_read_unlock(); |
| |
| return new_cpu; |
| } |
| |
| /* |
| * Called immediately before a task is migrated to a new cpu; task_cpu(p) and |
| * cfs_rq_of(p) references at time of call are still valid and identify the |
| * previous cpu. The caller guarantees p->pi_lock or task_rq(p)->lock is held. |
| */ |
| static void migrate_task_rq_fair(struct task_struct *p) |
| { |
| /* |
| * As blocked tasks retain absolute vruntime the migration needs to |
| * deal with this by subtracting the old and adding the new |
| * min_vruntime -- the latter is done by enqueue_entity() when placing |
| * the task on the new runqueue. |
| */ |
| if (p->state == TASK_WAKING) { |
| struct sched_entity *se = &p->se; |
| struct cfs_rq *cfs_rq = cfs_rq_of(se); |
| u64 min_vruntime; |
| |
| #ifndef CONFIG_64BIT |
| u64 min_vruntime_copy; |
| |
| do { |
| min_vruntime_copy = cfs_rq->min_vruntime_copy; |
| smp_rmb(); |
| min_vruntime = cfs_rq->min_vruntime; |
| } while (min_vruntime != min_vruntime_copy); |
| #else |
| min_vruntime = cfs_rq->min_vruntime; |
| #endif |
| |
| se->vruntime -= min_vruntime; |
| } |
| |
| /* |
| * We are supposed to update the task to "current" time, then its up to date |
| * and ready to go to new CPU/cfs_rq. But we have difficulty in getting |
| * what current time is, so simply throw away the out-of-date time. This |
| * will result in the wakee task is less decayed, but giving the wakee more |
| * load sounds not bad. |
| */ |
| remove_entity_load_avg(&p->se); |
| |
| /* Tell new CPU we are migrated */ |
| p->se.avg.last_update_time = 0; |
| |
| /* We have migrated, no longer consider this task hot */ |
| p->se.exec_start = 0; |
| } |
| |
| static void task_dead_fair(struct task_struct *p) |
| { |
| remove_entity_load_avg(&p->se); |
| } |
| #else |
| #define task_fits_max(p, cpu) true |
| #endif /* CONFIG_SMP */ |
| |
| static unsigned long |
| wakeup_gran(struct sched_entity *curr, struct sched_entity *se) |
| { |
| unsigned long gran = sysctl_sched_wakeup_granularity; |
| |
| /* |
| * Since its curr running now, convert the gran from real-time |
| * to virtual-time in his units. |
| * |
| * By using 'se' instead of 'curr' we penalize light tasks, so |
| * they get preempted easier. That is, if 'se' < 'curr' then |
| * the resulting gran will be larger, therefore penalizing the |
| * lighter, if otoh 'se' > 'curr' then the resulting gran will |
| * be smaller, again penalizing the lighter task. |
| * |
| * This is especially important for buddies when the leftmost |
| * task is higher priority than the buddy. |
| */ |
| return calc_delta_fair(gran, se); |
| } |
| |
| /* |
| * Should 'se' preempt 'curr'. |
| * |
| * |s1 |
| * |s2 |
| * |s3 |
| * g |
| * |<--->|c |
| * |
| * w(c, s1) = -1 |
| * w(c, s2) = 0 |
| * w(c, s3) = 1 |
| * |
| */ |
| static int |
| wakeup_preempt_entity(struct sched_entity *curr, struct sched_entity *se) |
| { |
| s64 gran, vdiff = curr->vruntime - se->vruntime; |
| |
| if (vdiff <= 0) |
| return -1; |
| |
| gran = wakeup_gran(curr, se); |
| if (vdiff > gran) |
| return 1; |
| |
| return 0; |
| } |
| |
| static void set_last_buddy(struct sched_entity *se) |
| { |
| if (entity_is_task(se) && unlikely(task_of(se)->policy == SCHED_IDLE)) |
| return; |
| |
| for_each_sched_entity(se) |
| cfs_rq_of(se)->last = se; |
| } |
| |
| static void set_next_buddy(struct sched_entity *se) |
| { |
| if (entity_is_task(se) && unlikely(task_of(se)->policy == SCHED_IDLE)) |
| return; |
| |
| for_each_sched_entity(se) |
| cfs_rq_of(se)->next = se; |
| } |
| |
| static void set_skip_buddy(struct sched_entity *se) |
| { |
| for_each_sched_entity(se) |
| cfs_rq_of(se)->skip = se; |
| } |
| |
| /* |
| * Preempt the current task with a newly woken task if needed: |
| */ |
| static void check_preempt_wakeup(struct rq *rq, struct task_struct *p, int wake_flags) |
| { |
| struct task_struct *curr = rq->curr; |
| struct sched_entity *se = &curr->se, *pse = &p->se; |
| struct cfs_rq *cfs_rq = task_cfs_rq(curr); |
| int scale = cfs_rq->nr_running >= sched_nr_latency; |
| int next_buddy_marked = 0; |
| |
| if (unlikely(se == pse)) |
| return; |
| |
| /* |
| * This is possible from callers such as attach_tasks(), in which we |
| * unconditionally check_prempt_curr() after an enqueue (which may have |
| * lead to a throttle). This both saves work and prevents false |
| * next-buddy nomination below. |
| */ |
| if (unlikely(throttled_hierarchy(cfs_rq_of(pse)))) |
| return; |
| |
| if (sched_feat(NEXT_BUDDY) && scale && !(wake_flags & WF_FORK)) { |
| set_next_buddy(pse); |
| next_buddy_marked = 1; |
| } |
| |
| /* |
| * We can come here with TIF_NEED_RESCHED already set from new task |
| * wake up path. |
| * |
| * Note: this also catches the edge-case of curr being in a throttled |
| * group (e.g. via set_curr_task), since update_curr() (in the |
| * enqueue of curr) will have resulted in resched being set. This |
| * prevents us from potentially nominating it as a false LAST_BUDDY |
| * below. |
| */ |
| if (test_tsk_need_resched(curr)) |
| return; |
| |
| /* Idle tasks are by definition preempted by non-idle tasks. */ |
| if (unlikely(curr->policy == SCHED_IDLE) && |
| likely(p->policy != SCHED_IDLE)) |
| goto preempt; |
| |
| /* |
| * Batch and idle tasks do not preempt non-idle tasks (their preemption |
| * is driven by the tick): |
| */ |
| if (unlikely(p->policy != SCHED_NORMAL) || !sched_feat(WAKEUP_PREEMPTION)) |
| return; |
| |
| find_matching_se(&se, &pse); |
| update_curr(cfs_rq_of(se)); |
| BUG_ON(!pse); |
| if (wakeup_preempt_entity(se, pse) == 1) { |
| /* |
| * Bias pick_next to pick the sched entity that is |
| * triggering this preemption. |
| */ |
| if (!next_buddy_marked) |
| set_next_buddy(pse); |
| goto preempt; |
| } |
| |
| return; |
| |
| preempt: |
| resched_curr(rq); |
| /* |
| * Only set the backward buddy when the current task is still |
| * on the rq. This can happen when a wakeup gets interleaved |
| * with schedule on the ->pre_schedule() or idle_balance() |
| * point, either of which can * drop the rq lock. |
| * |
| * Also, during early boot the idle thread is in the fair class, |
| * for obvious reasons its a bad idea to schedule back to it. |
| */ |
| if (unlikely(!se->on_rq || curr == rq->idle)) |
| return; |
| |
| if (sched_feat(LAST_BUDDY) && scale && entity_is_task(se)) |
| set_last_buddy(se); |
| } |
| |
| static struct task_struct * |
| pick_next_task_fair(struct rq *rq, struct task_struct *prev, struct pin_cookie cookie) |
| { |
| struct cfs_rq *cfs_rq = &rq->cfs; |
| struct sched_entity *se; |
| struct task_struct *p; |
| int new_tasks; |
| |
| again: |
| #ifdef CONFIG_FAIR_GROUP_SCHED |
| if (!cfs_rq->nr_running) |
| goto idle; |
| |
| if (prev->sched_class != &fair_sched_class) |
| goto simple; |
| |
| /* |
| * Because of the set_next_buddy() in dequeue_task_fair() it is rather |
| * likely that a next task is from the same cgroup as the current. |
| * |
| * Therefore attempt to avoid putting and setting the entire cgroup |
| * hierarchy, only change the part that actually changes. |
| */ |
| |
| do { |
| struct sched_entity *curr = cfs_rq->curr; |
| |
| /* |
| * Since we got here without doing put_prev_entity() we also |
| * have to consider cfs_rq->curr. If it is still a runnable |
| * entity, update_curr() will update its vruntime, otherwise |
| * forget we've ever seen it. |
| */ |
| if (curr) { |
| if (curr->on_rq) |
| update_curr(cfs_rq); |
| else |
| curr = NULL; |
| |
| /* |
| * This call to check_cfs_rq_runtime() will do the |
| * throttle and dequeue its entity in the parent(s). |
| * Therefore the 'simple' nr_running test will indeed |
| * be correct. |
| */ |
| if (unlikely(check_cfs_rq_runtime(cfs_rq))) |
| goto simple; |
| } |
| |
| se = pick_next_entity(cfs_rq, curr); |
| cfs_rq = group_cfs_rq(se); |
| } while (cfs_rq); |
| |
| p = task_of(se); |
| |
| /* |
| * Since we haven't yet done put_prev_entity and if the selected task |
| * is a different task than we started out with, try and touch the |
| * least amount of cfs_rqs. |
| */ |
| if (prev != p) { |
| struct sched_entity *pse = &prev->se; |
| |
| while (!(cfs_rq = is_same_group(se, pse))) { |
| int se_depth = se->depth; |
| int pse_depth = pse->depth; |
| |
| if (se_depth <= pse_depth) { |
| put_prev_entity(cfs_rq_of(pse), pse); |
| pse = parent_entity(pse); |
| } |
| if (se_depth >= pse_depth) { |
| set_next_entity(cfs_rq_of(se), se); |
| se = parent_entity(se); |
| } |
| } |
| |
| put_prev_entity(cfs_rq, pse); |
| set_next_entity(cfs_rq, se); |
| } |
| |
| if (hrtick_enabled(rq)) |
| hrtick_start_fair(rq, p); |
| |
| rq->misfit_task = !task_fits_max(p, rq->cpu); |
| |
| return p; |
| simple: |
| cfs_rq = &rq->cfs; |
| #endif |
| |
| if (!cfs_rq->nr_running) |
| goto idle; |
| |
| put_prev_task(rq, prev); |
| |
| do { |
| se = pick_next_entity(cfs_rq, NULL); |
| set_next_entity(cfs_rq, se); |
| cfs_rq = group_cfs_rq(se); |
| } while (cfs_rq); |
| |
| p = task_of(se); |
| |
| if (hrtick_enabled(rq)) |
| hrtick_start_fair(rq, p); |
| |
| rq->misfit_task = !task_fits_max(p, rq->cpu); |
| |
| return p; |
| |
| idle: |
| rq->misfit_task = 0; |
| /* |
| * This is OK, because current is on_cpu, which avoids it being picked |
| * for load-balance and preemption/IRQs are still disabled avoiding |
| * further scheduler activity on it and we're being very careful to |
| * re-start the picking loop. |
| */ |
| lockdep_unpin_lock(&rq->lock, cookie); |
| new_tasks = idle_balance(rq); |
| lockdep_repin_lock(&rq->lock, cookie); |
| /* |
| * Because idle_balance() releases (and re-acquires) rq->lock, it is |
| * possible for any higher priority task to appear. In that case we |
| * must re-start the pick_next_entity() loop. |
| */ |
| if (new_tasks < 0) |
| return RETRY_TASK; |
| |
| if (new_tasks > 0) |
| goto again; |
| |
| return NULL; |
| } |
| |
| /* |
| * Account for a descheduled task: |
| */ |
| static void put_prev_task_fair(struct rq *rq, struct task_struct *prev) |
| { |
| struct sched_entity *se = &prev->se; |
| struct cfs_rq *cfs_rq; |
| |
| for_each_sched_entity(se) { |
| cfs_rq = cfs_rq_of(se); |
| put_prev_entity(cfs_rq, se); |
| } |
| } |
| |
| /* |
| * sched_yield() is very simple |
| * |
| * The magic of dealing with the ->skip buddy is in pick_next_entity. |
| */ |
| static void yield_task_fair(struct rq *rq) |
| { |
| struct task_struct *curr = rq->curr; |
| struct cfs_rq *cfs_rq = task_cfs_rq(curr); |
| struct sched_entity *se = &curr->se; |
| |
| /* |
| * Are we the only task in the tree? |
| */ |
| if (unlikely(rq->nr_running == 1)) |
| return; |
| |
| clear_buddies(cfs_rq, se); |
| |
| if (curr->policy != SCHED_BATCH) { |
| update_rq_clock(rq); |
| /* |
| * Update run-time statistics of the 'current'. |
| */ |
| update_curr(cfs_rq); |
| /* |
| * Tell update_rq_clock() that we've just updated, |
| * so we don't do microscopic update in schedule() |
| * and double the fastpath cost. |
| */ |
| rq_clock_skip_update(rq, true); |
| } |
| |
| set_skip_buddy(se); |
| } |
| |
| static bool yield_to_task_fair(struct rq *rq, struct task_struct *p, bool preempt) |
| { |
| struct sched_entity *se = &p->se; |
| |
| /* throttled hierarchies are not runnable */ |
| if (!se->on_rq || throttled_hierarchy(cfs_rq_of(se))) |
| return false; |
| |
| /* Tell the scheduler that we'd really like pse to run next. */ |
| set_next_buddy(se); |
| |
| yield_task_fair(rq); |
| |
| return true; |
| } |
| |
| #ifdef CONFIG_SMP |
| /************************************************** |
| * Fair scheduling class load-balancing methods. |
| * |
| * BASICS |
| * |
| * The purpose of load-balancing is to achieve the same basic fairness the |
| * per-cpu scheduler provides, namely provide a proportional amount of compute |
| * time to each task. This is expressed in the following equation: |
| * |
| * W_i,n/P_i == W_j,n/P_j for all i,j (1) |
| * |
| * Where W_i,n is the n-th weight average for cpu i. The instantaneous weight |
| * W_i,0 is defined as: |
| * |
| * W_i,0 = \Sum_j w_i,j (2) |
| * |
| * Where w_i,j is the weight of the j-th runnable task on cpu i. This weight |
| * is derived from the nice value as per sched_prio_to_weight[]. |
| * |
| * The weight average is an exponential decay average of the instantaneous |
| * weight: |
| * |
| * W'_i,n = (2^n - 1) / 2^n * W_i,n + 1 / 2^n * W_i,0 (3) |
| * |
| * C_i is the compute capacity of cpu i, typically it is the |
| * fraction of 'recent' time available for SCHED_OTHER task execution. But it |
| * can also include other factors [XXX]. |
| * |
| * To achieve this balance we define a measure of imbalance which follows |
| * directly from (1): |
| * |
| * imb_i,j = max{ avg(W/C), W_i/C_i } - min{ avg(W/C), W_j/C_j } (4) |
| * |
| * We them move tasks around to minimize the imbalance. In the continuous |
| * function space it is obvious this converges, in the discrete case we get |
| * a few fun cases generally called infeasible weight scenarios. |
| * |
| * [XXX expand on: |
| * - infeasible weights; |
| * - local vs global optima in the discrete case. ] |
| * |
| * |
| * SCHED DOMAINS |
| * |
| * In order to solve the imbalance equation (4), and avoid the obvious O(n^2) |
| * for all i,j solution, we create a tree of cpus that follows the hardware |
| * topology where each level pairs two lower groups (or better). This results |
| * in O(log n) layers. Furthermore we reduce the number of cpus going up the |
| * tree to only the first of the previous level and we decrease the frequency |
| * of load-balance at each level inv. proportional to the number of cpus in |
| * the groups. |
| * |
| * This yields: |
| * |
| * log_2 n 1 n |
| * \Sum { --- * --- * 2^i } = O(n) (5) |
| * i = 0 2^i 2^i |
| * `- size of each group |
| * | | `- number of cpus doing load-balance |
| * | `- freq |
| * `- sum over all levels |
| * |
| * Coupled with a limit on how many tasks we can migrate every balance pass, |
| * this makes (5) the runtime complexity of the balancer. |
| * |
| * An important property here is that each CPU is still (indirectly) connected |
| * to every other cpu in at most O(log n) steps: |
| * |
| * The adjacency matrix of the resulting graph is given by: |
| * |
| * log_2 n |
| * A_i,j = \Union (i % 2^k == 0) && i / 2^(k+1) == j / 2^(k+1) (6) |
| * k = 0 |
| * |
| * And you'll find that: |
| * |
| * A^(log_2 n)_i,j != 0 for all i,j (7) |
| * |
| * Showing there's indeed a path between every cpu in at most O(log n) steps. |
| * The task movement gives a factor of O(m), giving a convergence complexity |
| * of: |
| * |
| * O(nm log n), n := nr_cpus, m := nr_tasks (8) |
| * |
| * |
| * WORK CONSERVING |
| * |
| * In order to avoid CPUs going idle while there's still work to do, new idle |
| * balancing is more aggressive and has the newly idle cpu iterate up the domain |
| * tree itself instead of relying on other CPUs to bring it work. |
| * |
| * This adds some complexity to both (5) and (8) but it reduces the total idle |
| * time. |
| * |
| * [XXX more?] |
| * |
| * |
| * CGROUPS |
| * |
| * Cgroups make a horror show out of (2), instead of a simple sum we get: |
| * |
| * s_k,i |
| * W_i,0 = \Sum_j \Prod_k w_k * ----- (9) |
| * S_k |
| * |
| * Where |
| * |
| * s_k,i = \Sum_j w_i,j,k and S_k = \Sum_i s_k,i (10) |
| * |
| * w_i,j,k is the weight of the j-th runnable task in the k-th cgroup on cpu i. |
| * |
| * The big problem is S_k, its a global sum needed to compute a local (W_i) |
| * property. |
| * |
| * [XXX write more on how we solve this.. _after_ merging pjt's patches that |
| * rewrite all of this once again.] |
| */ |
| |
| static unsigned long __read_mostly max_load_balance_interval = HZ/10; |
| |
| enum fbq_type { regular, remote, all }; |
| |
| enum group_type { |
| group_other = 0, |
| group_misfit_task, |
| group_imbalanced, |
| group_overloaded, |
| }; |
| |
| #define LBF_ALL_PINNED 0x01 |
| #define LBF_NEED_BREAK 0x02 |
| #define LBF_DST_PINNED 0x04 |
| #define LBF_SOME_PINNED 0x08 |
| #define LBF_BIG_TASK_ACTIVE_BALANCE 0x80 |
| #define LBF_IGNORE_BIG_TASKS 0x100 |
| #define LBF_IGNORE_PREFERRED_CLUSTER_TASKS 0x200 |
| #define LBF_MOVED_RELATED_THREAD_GROUP_TASK 0x400 |
| |
| struct lb_env { |
| struct sched_domain *sd; |
| |
| struct rq *src_rq; |
| int src_cpu; |
| |
| int dst_cpu; |
| struct rq *dst_rq; |
| |
| struct cpumask *dst_grpmask; |
| int new_dst_cpu; |
| enum cpu_idle_type idle; |
| long imbalance; |
| unsigned int src_grp_nr_running; |
| /* The set of CPUs under consideration for load-balancing */ |
| struct cpumask *cpus; |
| unsigned int busiest_grp_capacity; |
| unsigned int busiest_nr_running; |
| |
| unsigned int flags; |
| |
| unsigned int loop; |
| unsigned int loop_break; |
| unsigned int loop_max; |
| |
| enum fbq_type fbq_type; |
| struct list_head tasks; |
| enum sched_boost_policy boost_policy; |
| }; |
| |
| /* |
| * Is this task likely cache-hot: |
| */ |
| static int task_hot(struct task_struct *p, struct lb_env *env) |
| { |
| s64 delta; |
| |
| lockdep_assert_held(&env->src_rq->lock); |
| |
| if (p->sched_class != &fair_sched_class) |
| return 0; |
| |
| if (unlikely(p->policy == SCHED_IDLE)) |
| return 0; |
| |
| /* |
| * Buddy candidates are cache hot: |
| */ |
| if (sched_feat(CACHE_HOT_BUDDY) && env->dst_rq->nr_running && |
| (&p->se == cfs_rq_of(&p->se)->next || |
| &p->se == cfs_rq_of(&p->se)->last)) |
| return 1; |
| |
| if (sysctl_sched_migration_cost == -1) |
| return 1; |
| if (sysctl_sched_migration_cost == 0) |
| return 0; |
| |
| delta = rq_clock_task(env->src_rq) - p->se.exec_start; |
| |
| return delta < (s64)sysctl_sched_migration_cost; |
| } |
| |
| #ifdef CONFIG_NUMA_BALANCING |
| /* |
| * Returns 1, if task migration degrades locality |
| * Returns 0, if task migration improves locality i.e migration preferred. |
| * Returns -1, if task migration is not affected by locality. |
| */ |
| static int migrate_degrades_locality(struct task_struct *p, struct lb_env *env) |
| { |
| struct numa_group *numa_group = rcu_dereference(p->numa_group); |
| unsigned long src_faults, dst_faults; |
| int src_nid, dst_nid; |
| |
| if (!static_branch_likely(&sched_numa_balancing)) |
| return -1; |
| |
| if (!p->numa_faults || !(env->sd->flags & SD_NUMA)) |
| return -1; |
| |
| src_nid = cpu_to_node(env->src_cpu); |
| dst_nid = cpu_to_node(env->dst_cpu); |
| |
| if (src_nid == dst_nid) |
| return -1; |
| |
| /* Migrating away from the preferred node is always bad. */ |
| if (src_nid == p->numa_preferred_nid) { |
| if (env->src_rq->nr_running > env->src_rq->nr_preferred_running) |
| return 1; |
| else |
| return -1; |
| } |
| |
| /* Encourage migration to the preferred node. */ |
| if (dst_nid == p->numa_preferred_nid) |
| return 0; |
| |
| if (numa_group) { |
| src_faults = group_faults(p, src_nid); |
| dst_faults = group_faults(p, dst_nid); |
| } else { |
| src_faults = task_faults(p, src_nid); |
| dst_faults = task_faults(p, dst_nid); |
| } |
| |
| return dst_faults < src_faults; |
| } |
| |
| #else |
| static inline int migrate_degrades_locality(struct task_struct *p, |
| struct lb_env *env) |
| { |
| return -1; |
| } |
| #endif |
| |
| /* |
| * can_migrate_task - may task p from runqueue rq be migrated to this_cpu? |
| */ |
| static |
| int can_migrate_task(struct task_struct *p, struct lb_env *env) |
| { |
| int tsk_cache_hot; |
| int twf, group_cpus; |
| |
| lockdep_assert_held(&env->src_rq->lock); |
| |
| /* |
| * We do not migrate tasks that are: |
| * 1) throttled_lb_pair, or |
| * 2) cannot be migrated to this CPU due to cpus_allowed, or |
| * 3) running (obviously), or |
| * 4) are cache-hot on their current CPU. |
| */ |
| if (throttled_lb_pair(task_group(p), env->src_cpu, env->dst_cpu)) |
| return 0; |
| |
| if (!cpumask_test_cpu(env->dst_cpu, tsk_cpus_allowed(p))) { |
| int cpu; |
| |
| schedstat_inc(p->se.statistics.nr_failed_migrations_affine); |
| |
| env->flags |= LBF_SOME_PINNED; |
| |
| /* |
| * Remember if this task can be migrated to any other cpu in |
| * our sched_group. We may want to revisit it if we couldn't |
| * meet load balance goals by pulling other tasks on src_cpu. |
| * |
| * Also avoid computing new_dst_cpu if we have already computed |
| * one in current iteration. |
| */ |
| if (!env->dst_grpmask || (env->flags & LBF_DST_PINNED)) |
| return 0; |
| |
| /* Prevent to re-select dst_cpu via env's cpus */ |
| for_each_cpu_and(cpu, env->dst_grpmask, env->cpus) { |
| if (cpumask_test_cpu(cpu, tsk_cpus_allowed(p))) { |
| env->flags |= LBF_DST_PINNED; |
| env->new_dst_cpu = cpu; |
| break; |
| } |
| } |
| |
| return 0; |
| } |
| |
| /* Record that we found atleast one task that could run on dst_cpu */ |
| env->flags &= ~LBF_ALL_PINNED; |
| |
| if (cpu_capacity(env->dst_cpu) > cpu_capacity(env->src_cpu)) { |
| if (nr_big_tasks(env->src_rq) && !is_big_task(p)) |
| return 0; |
| |
| if (env->boost_policy == SCHED_BOOST_ON_BIG && |
| !task_sched_boost(p)) |
| return 0; |
| } |
| |
| twf = task_will_fit(p, env->dst_cpu); |
| |
| /* |
| * Attempt to not pull tasks that don't fit. We may get lucky and find |
| * one that actually fits. |
| */ |
| if (env->flags & LBF_IGNORE_BIG_TASKS && !twf) |
| return 0; |
| |
| if (env->flags & LBF_IGNORE_PREFERRED_CLUSTER_TASKS && |
| !preferred_cluster(rq_cluster(cpu_rq(env->dst_cpu)), p)) |
| return 0; |
| |
| /* |
| * Group imbalance can sometimes cause work to be pulled across groups |
| * even though the group could have managed the imbalance on its own. |
| * Prevent inter-cluster migrations for big tasks when the number of |
| * tasks is lower than the capacity of the group. |
| */ |
| group_cpus = DIV_ROUND_UP(env->busiest_grp_capacity, |
| SCHED_CAPACITY_SCALE); |
| if (!twf && env->busiest_nr_running <= group_cpus) |
| return 0; |
| |
| if (task_running(env->src_rq, p)) { |
| schedstat_inc(p->se.statistics.nr_failed_migrations_running); |
| return 0; |
| } |
| |
| /* |
| * Aggressive migration if: |
| * 1) IDLE or NEWLY_IDLE balance. |
| * 2) destination numa is preferred |
| * 3) task is cache cold, or |
| * 4) too many balance attempts have failed. |
| */ |
| tsk_cache_hot = migrate_degrades_locality(p, env); |
| if (tsk_cache_hot == -1) |
| tsk_cache_hot = task_hot(p, env); |
| |
| if (env->idle != CPU_NOT_IDLE || tsk_cache_hot <= 0 || |
| env->sd->nr_balance_failed > env->sd->cache_nice_tries) { |
| if (tsk_cache_hot == 1) { |
| schedstat_inc(env->sd->lb_hot_gained[env->idle]); |
| schedstat_inc(p->se.statistics.nr_forced_migrations); |
| } |
| return 1; |
| } |
| |
| schedstat_inc(p->se.statistics.nr_failed_migrations_hot); |
| return 0; |
| } |
| |
| /* |
| * detach_task() -- detach the task for the migration specified in env |
| */ |
| static void detach_task(struct task_struct *p, struct lb_env *env) |
| { |
| lockdep_assert_held(&env->src_rq->lock); |
| |
| p->on_rq = TASK_ON_RQ_MIGRATING; |
| deactivate_task(env->src_rq, p, 0); |
| double_lock_balance(env->src_rq, env->dst_rq); |
| set_task_cpu(p, env->dst_cpu); |
| if (task_in_related_thread_group(p)) |
| env->flags |= LBF_MOVED_RELATED_THREAD_GROUP_TASK; |
| double_unlock_balance(env->src_rq, env->dst_rq); |
| } |
| |
| /* |
| * detach_one_task() -- tries to dequeue exactly one task from env->src_rq, as |
| * part of active balancing operations within "domain". |
| * |
| * Returns a task if successful and NULL otherwise. |
| */ |
| static struct task_struct *detach_one_task(struct lb_env *env) |
| { |
| struct task_struct *p, *n; |
| |
| lockdep_assert_held(&env->src_rq->lock); |
| |
| list_for_each_entry_safe(p, n, &env->src_rq->cfs_tasks, se.group_node) { |
| if (!can_migrate_task(p, env)) |
| continue; |
| |
| detach_task(p, env); |
| |
| /* |
| * Right now, this is only the second place where |
| * lb_gained[env->idle] is updated (other is detach_tasks) |
| * so we can safely collect stats here rather than |
| * inside detach_tasks(). |
| */ |
| schedstat_inc(env->sd->lb_gained[env->idle]); |
| return p; |
| } |
| return NULL; |
| } |
| |
| static const unsigned int sched_nr_migrate_break = 32; |
| |
| /* |
| * detach_tasks() -- tries to detach up to imbalance weighted load from |
| * busiest_rq, as part of a balancing operation within domain "sd". |
| * |
| * Returns number of detached tasks if successful and 0 otherwise. |
| */ |
| static int detach_tasks(struct lb_env *env) |
| { |
| struct list_head *tasks = &env->src_rq->cfs_tasks; |
| struct task_struct *p; |
| unsigned long load; |
| int detached = 0; |
| int orig_loop = env->loop; |
| |
| lockdep_assert_held(&env->src_rq->lock); |
| |
| if (env->imbalance <= 0) |
| return 0; |
| |
| if (!same_cluster(env->dst_cpu, env->src_cpu)) |
| env->flags |= LBF_IGNORE_PREFERRED_CLUSTER_TASKS; |
| |
| if (cpu_capacity(env->dst_cpu) < cpu_capacity(env->src_cpu)) |
| env->flags |= LBF_IGNORE_BIG_TASKS; |
| |
| redo: |
| while (!list_empty(tasks)) { |
| /* |
| * We don't want to steal all, otherwise we may be treated likewise, |
| * which could at worst lead to a livelock crash. |
| */ |
| if (env->idle != CPU_NOT_IDLE && env->src_rq->nr_running <= 1) |
| break; |
| |
| p = list_first_entry(tasks, struct task_struct, se.group_node); |
| |
| env->loop++; |
| /* We've more or less seen every task there is, call it quits */ |
| if (env->loop > env->loop_max) |
| break; |
| |
| /* take a breather every nr_migrate tasks */ |
| if (env->loop > env->loop_break) { |
| env->loop_break += sched_nr_migrate_break; |
| env->flags |= LBF_NEED_BREAK; |
| break; |
| } |
| |
| if (!can_migrate_task(p, env)) |
| goto next; |
| |
| load = task_h_load(p); |
| |
| if (sched_feat(LB_MIN) && load < 16 && !env->sd->nr_balance_failed) |
| goto next; |
| |
| if ((load / 2) > env->imbalance) |
| goto next; |
| |
| detach_task(p, env); |
| list_add(&p->se.group_node, &env->tasks); |
| |
| detached++; |
| env->imbalance -= load; |
| |
| #ifdef CONFIG_PREEMPT |
| /* |
| * NEWIDLE balancing is a source of latency, so preemptible |
| * kernels will stop after the first task is detached to minimize |
| * the critical section. |
| */ |
| if (env->idle == CPU_NEWLY_IDLE) |
| break; |
| #endif |
| |
| /* |
| * We only want to steal up to the prescribed amount of |
| * weighted load. |
| */ |
| if (env->imbalance <= 0) |
| break; |
| |
| continue; |
| next: |
| list_move_tail(&p->se.group_node, tasks); |
| } |
| |
| if (env->flags & (LBF_IGNORE_BIG_TASKS | |
| LBF_IGNORE_PREFERRED_CLUSTER_TASKS) && !detached) { |
| tasks = &env->src_rq->cfs_tasks; |
| env->flags &= ~(LBF_IGNORE_BIG_TASKS | |
| LBF_IGNORE_PREFERRED_CLUSTER_TASKS); |
| env->loop = orig_loop; |
| goto redo; |
| } |
| |
| /* |
| * Right now, this is one of only two places we collect this stat |
| * so we can safely collect detach_one_task() stats here rather |
| * than inside detach_one_task(). |
| */ |
| schedstat_add(env->sd->lb_gained[env->idle], detached); |
| |
| return detached; |
| } |
| |
| /* |
| * attach_task() -- attach the task detached by detach_task() to its new rq. |
| */ |
| static void attach_task(struct rq *rq, struct task_struct *p) |
| { |
| lockdep_assert_held(&rq->lock); |
| |
| BUG_ON(task_rq(p) != rq); |
| activate_task(rq, p, 0); |
| p->on_rq = TASK_ON_RQ_QUEUED; |
| check_preempt_curr(rq, p, 0); |
| } |
| |
| /* |
| * attach_one_task() -- attaches the task returned from detach_one_task() to |
| * its new rq. |
| */ |
| static void attach_one_task(struct rq *rq, struct task_struct *p) |
| { |
| raw_spin_lock(&rq->lock); |
| attach_task(rq, p); |
| /* |
| * We want to potentially raise target_cpu's OPP. |
| */ |
| update_capacity_of(cpu_of(rq)); |
| raw_spin_unlock(&rq->lock); |
| } |
| |
| /* |
| * attach_tasks() -- attaches all tasks detached by detach_tasks() to their |
| * new rq. |
| */ |
| static void attach_tasks(struct lb_env *env) |
| { |
| struct list_head *tasks = &env->tasks; |
| struct task_struct *p; |
| |
| raw_spin_lock(&env->dst_rq->lock); |
| |
| while (!list_empty(tasks)) { |
| p = list_first_entry(tasks, struct task_struct, se.group_node); |
| list_del_init(&p->se.group_node); |
| |
| attach_task(env->dst_rq, p); |
| } |
| |
| /* |
| * We want to potentially raise env.dst_cpu's OPP. |
| */ |
| update_capacity_of(env->dst_cpu); |
| |
| raw_spin_unlock(&env->dst_rq->lock); |
| } |
| |
| #ifdef CONFIG_FAIR_GROUP_SCHED |
| static void update_blocked_averages(int cpu) |
| { |
| struct rq *rq = cpu_rq(cpu); |
| struct cfs_rq *cfs_rq; |
| unsigned long flags; |
| |
| raw_spin_lock_irqsave(&rq->lock, flags); |
| update_rq_clock(rq); |
| |
| /* |
| * Iterates the task_group tree in a bottom up fashion, see |
| * list_add_leaf_cfs_rq() for details. |
| */ |
| for_each_leaf_cfs_rq(rq, cfs_rq) { |
| /* throttled entities do not contribute to load */ |
| if (throttled_hierarchy(cfs_rq)) |
| continue; |
| |
| if (update_cfs_rq_load_avg(cfs_rq_clock_task(cfs_rq), cfs_rq, true)) |
| update_tg_load_avg(cfs_rq, 0); |
| } |
| raw_spin_unlock_irqrestore(&rq->lock, flags); |
| } |
| |
| /* |
| * Compute the hierarchical load factor for cfs_rq and all its ascendants. |
| * This needs to be done in a top-down fashion because the load of a child |
| * group is a fraction of its parents load. |
| */ |
| static void update_cfs_rq_h_load(struct cfs_rq *cfs_rq) |
| { |
| struct rq *rq = rq_of(cfs_rq); |
| struct sched_entity *se = cfs_rq->tg->se[cpu_of(rq)]; |
| unsigned long now = jiffies; |
| unsigned long load; |
| |
| if (cfs_rq->last_h_load_update == now) |
| return; |
| |
| cfs_rq->h_load_next = NULL; |
| for_each_sched_entity(se) { |
| cfs_rq = cfs_rq_of(se); |
| cfs_rq->h_load_next = se; |
| if (cfs_rq->last_h_load_update == now) |
| break; |
| } |
| |
| if (!se) { |
| cfs_rq->h_load = cfs_rq_load_avg(cfs_rq); |
| cfs_rq->last_h_load_update = now; |
| } |
| |
| while ((se = cfs_rq->h_load_next) != NULL) { |
| load = cfs_rq->h_load; |
| load = div64_ul(load * se->avg.load_avg, |
| cfs_rq_load_avg(cfs_rq) + 1); |
| cfs_rq = group_cfs_rq(se); |
| cfs_rq->h_load = load; |
| cfs_rq->last_h_load_update = now; |
| } |
| } |
| |
| static unsigned long task_h_load(struct task_struct *p) |
| { |
| struct cfs_rq *cfs_rq = task_cfs_rq(p); |
| |
| update_cfs_rq_h_load(cfs_rq); |
| return div64_ul(p->se.avg.load_avg * cfs_rq->h_load, |
| cfs_rq_load_avg(cfs_rq) + 1); |
| } |
| #else |
| static inline void update_blocked_averages(int cpu) |
| { |
| struct rq *rq = cpu_rq(cpu); |
| struct cfs_rq *cfs_rq = &rq->cfs; |
| unsigned long flags; |
| |
| raw_spin_lock_irqsave(&rq->lock, flags); |
| update_rq_clock(rq); |
| update_cfs_rq_load_avg(cfs_rq_clock_task(cfs_rq), cfs_rq, true); |
| raw_spin_unlock_irqrestore(&rq->lock, flags); |
| } |
| |
| static unsigned long task_h_load(struct task_struct *p) |
| { |
| return p->se.avg.load_avg; |
| } |
| #endif |
| |
| /********** Helpers for find_busiest_group ************************/ |
| |
| /* |
| * sg_lb_stats - stats of a sched_group required for load_balancing |
| */ |
| struct sg_lb_stats { |
| unsigned long avg_load; /*Avg load across the CPUs of the group */ |
| unsigned long group_load; /* Total load over the CPUs of the group */ |
| unsigned long sum_weighted_load; /* Weighted load of group's tasks */ |
| unsigned long load_per_task; |
| unsigned long group_capacity; |
| unsigned long group_util; /* Total utilization of the group */ |
| unsigned int sum_nr_running; /* Nr tasks running in the group */ |
| #ifdef CONFIG_SCHED_HMP |
| unsigned long sum_nr_big_tasks; |
| u64 group_cpu_load; /* Scaled load of all CPUs of the group */ |
| #endif |
| unsigned int idle_cpus; |
| unsigned int group_weight; |
| enum group_type group_type; |
| int group_no_capacity; |
| int group_misfit_task; /* A cpu has a task too big for its capacity */ |
| #ifdef CONFIG_NUMA_BALANCING |
| unsigned int nr_numa_running; |
| unsigned int nr_preferred_running; |
| #endif |
| }; |
| |
| /* |
| * sd_lb_stats - Structure to store the statistics of a sched_domain |
| * during load balancing. |
| */ |
| struct sd_lb_stats { |
| struct sched_group *busiest; /* Busiest group in this sd */ |
| struct sched_group *local; /* Local group in this sd */ |
| unsigned long total_load; /* Total load of all groups in sd */ |
| unsigned long total_capacity; /* Total capacity of all groups in sd */ |
| unsigned long avg_load; /* Average load across all groups in sd */ |
| |
| struct sg_lb_stats busiest_stat;/* Statistics of the busiest group */ |
| struct sg_lb_stats local_stat; /* Statistics of the local group */ |
| }; |
| |
| static inline void init_sd_lb_stats(struct sd_lb_stats *sds) |
| { |
| /* |
| * Skimp on the clearing to avoid duplicate work. We can avoid clearing |
| * local_stat because update_sg_lb_stats() does a full clear/assignment. |
| * We must however clear busiest_stat::avg_load because |
| * update_sd_pick_busiest() reads this before assignment. |
| */ |
| *sds = (struct sd_lb_stats){ |
| .busiest = NULL, |
| .local = NULL, |
| .total_load = 0UL, |
| .total_capacity = 0UL, |
| .busiest_stat = { |
| .avg_load = 0UL, |
| .sum_nr_running = 0, |
| .group_type = group_other, |
| #ifdef CONFIG_SCHED_HMP |
| .sum_nr_big_tasks = 0UL, |
| .group_cpu_load = 0ULL, |
| #endif |
| }, |
| }; |
| } |
| |
| /** |
| * get_sd_load_idx - Obtain the load index for a given sched domain. |
| * @sd: The sched_domain whose load_idx is to be obtained. |
| * @idle: The idle status of the CPU for whose sd load_idx is obtained. |
| * |
| * Return: The load index. |
| */ |
| static inline int get_sd_load_idx(struct sched_domain *sd, |
| enum cpu_idle_type idle) |
| { |
| int load_idx; |
| |
| switch (idle) { |
| case CPU_NOT_IDLE: |
| load_idx = sd->busy_idx; |
| break; |
| |
| case CPU_NEWLY_IDLE: |
| load_idx = sd->newidle_idx; |
| break; |
| default: |
| load_idx = sd->idle_idx; |
| break; |
| } |
| |
| return load_idx; |
| } |
| |
| static unsigned long scale_rt_capacity(int cpu) |
| { |
| struct rq *rq = cpu_rq(cpu); |
| u64 total, used, age_stamp, avg; |
| s64 delta; |
| |
| /* |
| * Since we're reading these variables without serialization make sure |
| * we read them once before doing sanity checks on them. |
| */ |
| age_stamp = READ_ONCE(rq->age_stamp); |
| avg = READ_ONCE(rq->rt_avg); |
| delta = __rq_clock_broken(rq) - age_stamp; |
| |
| if (unlikely(delta < 0)) |
| delta = 0; |
| |
| total = sched_avg_period() + delta; |
| |
| used = div_u64(avg, total); |
| |
| if (likely(used < SCHED_CAPACITY_SCALE)) |
| return SCHED_CAPACITY_SCALE - used; |
| |
| return 1; |
| } |
| |
| void init_max_cpu_capacity(struct max_cpu_capacity *mcc) |
| { |
| raw_spin_lock_init(&mcc->lock); |
| mcc->val = 0; |
| mcc->cpu = -1; |
| } |
| |
| static void update_cpu_capacity(struct sched_domain *sd, int cpu) |
| { |
| unsigned long capacity = arch_scale_cpu_capacity(sd, cpu); |
| struct sched_group *sdg = sd->groups; |
| struct max_cpu_capacity *mcc; |
| unsigned long max_capacity; |
| int max_cap_cpu; |
| unsigned long flags; |
| |
| cpu_rq(cpu)->cpu_capacity_orig = capacity; |
| |
| mcc = &cpu_rq(cpu)->rd->max_cpu_capacity; |
| |
| raw_spin_lock_irqsave(&mcc->lock, flags); |
| max_capacity = mcc->val; |
| max_cap_cpu = mcc->cpu; |
| |
| if ((max_capacity > capacity && max_cap_cpu == cpu) || |
| (max_capacity < capacity)) { |
| mcc->val = capacity; |
| mcc->cpu = cpu; |
| #ifdef CONFIG_SCHED_DEBUG |
| raw_spin_unlock_irqrestore(&mcc->lock, flags); |
| pr_info("CPU%d: update max cpu_capacity %lu\n", cpu, capacity); |
| goto skip_unlock; |
| #endif |
| } |
| raw_spin_unlock_irqrestore(&mcc->lock, flags); |
| |
| skip_unlock: __attribute__ ((unused)); |
| capacity *= scale_rt_capacity(cpu); |
| capacity >>= SCHED_CAPACITY_SHIFT; |
| |
| if (!capacity) |
| capacity = 1; |
| |
| cpu_rq(cpu)->cpu_capacity = capacity; |
| sdg->sgc->capacity = capacity; |
| sdg->sgc->max_capacity = capacity; |
| } |
| |
| void update_group_capacity(struct sched_domain *sd, int cpu) |
| { |
| struct sched_domain *child = sd->child; |
| struct sched_group *group, *sdg = sd->groups; |
| unsigned long capacity, max_capacity; |
| unsigned long interval; |
| |
| interval = msecs_to_jiffies(sd->balance_interval); |
| interval = clamp(interval, 1UL, max_load_balance_interval); |
| sdg->sgc->next_update = jiffies + interval; |
| |
| if (!child) { |
| update_cpu_capacity(sd, cpu); |
| return; |
| } |
| |
| capacity = 0; |
| max_capacity = 0; |
| |
| if (child->flags & SD_OVERLAP) { |
| /* |
| * SD_OVERLAP domains cannot assume that child groups |
| * span the current group. |
| */ |
| |
| for_each_cpu(cpu, sched_group_cpus(sdg)) { |
| struct sched_group_capacity *sgc; |
| struct rq *rq = cpu_rq(cpu); |
| |
| if (cpumask_test_cpu(cpu, cpu_isolated_mask)) |
| continue; |
| /* |
| * build_sched_domains() -> init_sched_groups_capacity() |
| * gets here before we've attached the domains to the |
| * runqueues. |
| * |
| * Use capacity_of(), which is set irrespective of domains |
| * in update_cpu_capacity(). |
| * |
| * This avoids capacity from being 0 and |
| * causing divide-by-zero issues on boot. |
| */ |
| if (unlikely(!rq->sd)) { |
| capacity += capacity_of(cpu); |
| } else { |
| sgc = rq->sd->groups->sgc; |
| capacity += sgc->capacity; |
| } |
| |
| max_capacity = max(capacity, max_capacity); |
| } |
| } else { |
| /* |
| * !SD_OVERLAP domains can assume that child groups |
| * span the current group. |
| */ |
| |
| group = child->groups; |
| do { |
| struct sched_group_capacity *sgc = group->sgc; |
| cpumask_t *cpus = sched_group_cpus(group); |
| |
| /* Revisit this later. This won't work for MT domain */ |
| if (!cpu_isolated(cpumask_first(cpus))) { |
| capacity += sgc->capacity; |
| max_capacity = max(sgc->max_capacity, max_capacity); |
| } |
| group = group->next; |
| } while (group != child->groups); |
| } |
| |
| sdg->sgc->capacity = capacity; |
| sdg->sgc->max_capacity = max_capacity; |
| } |
| |
| /* |
| * Check whether the capacity of the rq has been noticeably reduced by side |
| * activity. The imbalance_pct is used for the threshold. |
| * Return true is the capacity is reduced |
| */ |
| static inline int |
| check_cpu_capacity(struct rq *rq, struct sched_domain *sd) |
| { |
| return ((rq->cpu_capacity * sd->imbalance_pct) < |
| (rq->cpu_capacity_orig * 100)); |
| } |
| |
| /* |
| * Group imbalance indicates (and tries to solve) the problem where balancing |
| * groups is inadequate due to tsk_cpus_allowed() constraints. |
| * |
| * Imagine a situation of two groups of 4 cpus each and 4 tasks each with a |
| * cpumask covering 1 cpu of the first group and 3 cpus of the second group. |
| * Something like: |
| * |
| * { 0 1 2 3 } { 4 5 6 7 } |
| * * * * * |
| * |
| * If we were to balance group-wise we'd place two tasks in the first group and |
| * two tasks in the second group. Clearly this is undesired as it will overload |
| * cpu 3 and leave one of the cpus in the second group unused. |
| * |
| * The current solution to this issue is detecting the skew in the first group |
| * by noticing the lower domain failed to reach balance and had difficulty |
| * moving tasks due to affinity constraints. |
| * |
| * When this is so detected; this group becomes a candidate for busiest; see |
| * update_sd_pick_busiest(). And calculate_imbalance() and |
| * find_busiest_group() avoid some of the usual balance conditions to allow it |
| * to create an effective group imbalance. |
| * |
| * This is a somewhat tricky proposition since the next run might not find the |
| * group imbalance and decide the groups need to be balanced again. A most |
| * subtle and fragile situation. |
| */ |
| |
| static inline int sg_imbalanced(struct sched_group *group) |
| { |
| return group->sgc->imbalance; |
| } |
| |
| /* |
| * group_has_capacity returns true if the group has spare capacity that could |
| * be used by some tasks. |
| * We consider that a group has spare capacity if the * number of task is |
| * smaller than the number of CPUs or if the utilization is lower than the |
| * available capacity for CFS tasks. |
| * For the latter, we use a threshold to stabilize the state, to take into |
| * account the variance of the tasks' load and to return true if the available |
| * capacity in meaningful for the load balancer. |
| * As an example, an available capacity of 1% can appear but it doesn't make |
| * any benefit for the load balance. |
| */ |
| static inline bool |
| group_has_capacity(struct lb_env *env, struct sg_lb_stats *sgs) |
| { |
| if (sgs->sum_nr_running < sgs->group_weight) |
| return true; |
| |
| if ((sgs->group_capacity * 100) > |
| (sgs->group_util * env->sd->imbalance_pct)) |
| return true; |
| |
| return false; |
| } |
| |
| /* |
| * group_is_overloaded returns true if the group has more tasks than it can |
| * handle. |
| * group_is_overloaded is not equals to !group_has_capacity because a group |
| * with the exact right number of tasks, has no more spare capacity but is not |
| * overloaded so both group_has_capacity and group_is_overloaded return |
| * false. |
| */ |
| static inline bool |
| group_is_overloaded(struct lb_env *env, struct sg_lb_stats *sgs) |
| { |
| if (sgs->sum_nr_running <= sgs->group_weight) |
| return false; |
| |
| if ((sgs->group_capacity * 100) < |
| (sgs->group_util * env->sd->imbalance_pct)) |
| return true; |
| |
| return false; |
| } |
| |
| static inline enum |
| group_type group_classify(struct sched_group *group, |
| struct sg_lb_stats *sgs) |
| { |
| if (sgs->group_no_capacity) |
| return group_overloaded; |
| |
| if (sg_imbalanced(group)) |
| return group_imbalanced; |
| |
| if (sgs->group_misfit_task) |
| return group_misfit_task; |
| |
| return group_other; |
| } |
| |
| /** |
| * update_sg_lb_stats - Update sched_group's statistics for load balancing. |
| * @env: The load balancing environment. |
| * @group: sched_group whose statistics are to be updated. |
| * @load_idx: Load index of sched_domain of this_cpu for load calc. |
| * @local_group: Does group contain this_cpu. |
| * @sgs: variable to hold the statistics for this group. |
| * @overload: Indicate more than one runnable task for any CPU. |
| * @overutilized: Indicate overutilization for any CPU. |
| */ |
| static inline void update_sg_lb_stats(struct lb_env *env, |
| struct sched_group *group, int load_idx, |
| int local_group, struct sg_lb_stats *sgs, |
| bool *overload, bool *overutilized) |
| { |
| unsigned long load; |
| int i, nr_running; |
| |
| memset(sgs, 0, sizeof(*sgs)); |
| |
| for_each_cpu_and(i, sched_group_cpus(group), env->cpus) { |
| struct rq *rq = cpu_rq(i); |
| |
| trace_sched_cpu_load_lb(cpu_rq(i), idle_cpu(i), |
| sched_irqload(i), |
| power_cost(i, 0), |
| cpu_temp(i)); |
| |
| if (cpu_isolated(i)) |
| continue; |
| |
| /* Bias balancing toward cpus of our domain */ |
| if (local_group) |
| load = target_load(i, load_idx); |
| else |
| load = source_load(i, load_idx); |
| |
| sgs->group_load += load; |
| sgs->group_util += cpu_util(i); |
| sgs->sum_nr_running += rq->cfs.h_nr_running; |
| |
| nr_running = rq->nr_running; |
| if (nr_running > 1) |
| *overload = true; |
| |
| #ifdef CONFIG_SCHED_HMP |
| sgs->sum_nr_big_tasks += rq->hmp_stats.nr_big_tasks; |
| sgs->group_cpu_load += cpu_load(i); |
| #endif |
| |
| #ifdef CONFIG_NUMA_BALANCING |
| sgs->nr_numa_running += rq->nr_numa_running; |
| sgs->nr_preferred_running += rq->nr_preferred_running; |
| #endif |
| sgs->sum_weighted_load += weighted_cpuload(i); |
| /* |
| * No need to call idle_cpu() if nr_running is not 0 |
| */ |
| if (!nr_running && idle_cpu(i)) |
| sgs->idle_cpus++; |
| |
| if (cpu_overutilized(i)) { |
| *overutilized = true; |
| if (!sgs->group_misfit_task && rq->misfit_task) |
| sgs->group_misfit_task = capacity_of(i); |
| } |
| } |
| |
| /* Isolated CPU has no weight */ |
| if (!group->group_weight) { |
| sgs->group_capacity = 0; |
| sgs->avg_load = 0; |
| sgs->group_no_capacity = 1; |
| sgs->group_type = group_other; |
| sgs->group_weight = group->group_weight; |
| } else { |
| /* Adjust by relative CPU capacity of the group */ |
| sgs->group_capacity = group->sgc->capacity; |
| sgs->avg_load = (sgs->group_load*SCHED_CAPACITY_SCALE) / |
| sgs->group_capacity; |
| |
| sgs->group_weight = group->group_weight; |
| |
| sgs->group_no_capacity = group_is_overloaded(env, sgs); |
| sgs->group_type = group_classify(group, sgs); |
| } |
| |
| if (sgs->sum_nr_running) |
| sgs->load_per_task = sgs->sum_weighted_load / sgs->sum_nr_running; |
| } |
| |
| /** |
| * update_sd_pick_busiest - return 1 on busiest group |
| * @env: The load balancing environment. |
| * @sds: sched_domain statistics |
| * @sg: sched_group candidate to be checked for being the busiest |
| * @sgs: sched_group statistics |
| * |
| * Determine if @sg is a busier group than the previously selected |
| * busiest group. |
| * |
| * Return: %true if @sg is a busier group than the previously selected |
| * busiest group. %false otherwise. |
| */ |
| static bool update_sd_pick_busiest(struct lb_env *env, |
| struct sd_lb_stats *sds, |
| struct sched_group *sg, |
| struct sg_lb_stats *sgs) |
| { |
| struct sg_lb_stats *busiest = &sds->busiest_stat; |
| |
| if (update_sd_pick_busiest_active_balance(env, sds, sg, sgs)) |
| return true; |
| |
| if (sgs->group_type > busiest->group_type) |
| return true; |
| |
| if (sgs->group_type < busiest->group_type) |
| return false; |
| |
| if (sgs->avg_load <= busiest->avg_load) |
| return false; |
| |
| /* This is the busiest node in its class. */ |
| if (!(env->sd->flags & SD_ASYM_PACKING)) |
| return true; |
| |
| /* No ASYM_PACKING if target cpu is already busy */ |
| if (env->idle == CPU_NOT_IDLE) |
| return true; |
| /* |
| * ASYM_PACKING needs to move all the work to the lowest |
| * numbered CPUs in the group, therefore mark all groups |
| * higher than ourself as busy. |
| */ |
| if (sgs->sum_nr_running && env->dst_cpu < group_first_cpu(sg)) { |
| if (!sds->busiest) |
| return true; |
| |
| /* Prefer to move from highest possible cpu's work */ |
| if (group_first_cpu(sds->busiest) < group_first_cpu(sg)) |
| return true; |
| } |
| |
| return false; |
| } |
| |
| #ifdef CONFIG_NUMA_BALANCING |
| static inline enum fbq_type fbq_classify_group(struct sg_lb_stats *sgs) |
| { |
| if (sgs->sum_nr_running > sgs->nr_numa_running) |
| return regular; |
| if (sgs->sum_nr_running > sgs->nr_preferred_running) |
| return remote; |
| return all; |
| } |
| |
| static inline enum fbq_type fbq_classify_rq(struct rq *rq) |
| { |
| if (rq->nr_running > rq->nr_numa_running) |
| return regular; |
| if (rq->nr_running > rq->nr_preferred_running) |
| return remote; |
| return all; |
| } |
| #else |
| static inline enum fbq_type fbq_classify_group(struct sg_lb_stats *sgs) |
| { |
| return all; |
| } |
| |
| static inline enum fbq_type fbq_classify_rq(struct rq *rq) |
| { |
| return regular; |
| } |
| #endif /* CONFIG_NUMA_BALANCING */ |
| |
| /** |
| * update_sd_lb_stats - Update sched_domain's statistics for load balancing. |
| * @env: The load balancing environment. |
| * @sds: variable to hold the statistics for this sched_domain. |
| */ |
| static inline void update_sd_lb_stats(struct lb_env *env, struct sd_lb_stats *sds) |
| { |
| struct sched_domain *child = env->sd->child; |
| struct sched_group *sg = env->sd->groups; |
| struct sg_lb_stats tmp_sgs; |
| int load_idx, prefer_sibling = 0; |
| bool overload = false, overutilized = false; |
| |
| if (child && child->flags & SD_PREFER_SIBLING) |
| prefer_sibling = 1; |
| |
| load_idx = get_sd_load_idx(env->sd, env->idle); |
| |
| do { |
| struct sg_lb_stats *sgs = &tmp_sgs; |
| int local_group; |
| |
| local_group = cpumask_test_cpu(env->dst_cpu, sched_group_cpus(sg)); |
| if (local_group) { |
| sds->local = sg; |
| sgs = &sds->local_stat; |
| |
| if (env->idle != CPU_NEWLY_IDLE || |
| time_after_eq(jiffies, sg->sgc->next_update)) |
| update_group_capacity(env->sd, env->dst_cpu); |
| } |
| |
| update_sg_lb_stats(env, sg, load_idx, local_group, sgs, |
| &overload, &overutilized); |
| |
| if (local_group) |
| goto next_group; |
| |
| /* |
| * In case the child domain prefers tasks go to siblings |
| * first, lower the sg capacity so that we'll try |
| * and move all the excess tasks away. We lower the capacity |
| * of a group only if the local group has the capacity to fit |
| * these excess tasks. The extra check prevents the case where |
| * you always pull from the heaviest group when it is already |
| * under-utilized (possible with a large weight task outweighs |
| * the tasks on the system). |
| */ |
| if (prefer_sibling && sds->local && |
| group_has_capacity(env, &sds->local_stat) && |
| (sgs->sum_nr_running > 1)) { |
| sgs->group_no_capacity = 1; |
| sgs->group_type = group_classify(sg, sgs); |
| } |
| |
| if (update_sd_pick_busiest(env, sds, sg, sgs)) { |
| sds->busiest = sg; |
| sds->busiest_stat = *sgs; |
| env->busiest_nr_running = sgs->sum_nr_running; |
| env->busiest_grp_capacity = sgs->group_capacity; |
| } |
| |
| next_group: |
| /* Now, start updating sd_lb_stats */ |
| sds->total_load += sgs->group_load; |
| sds->total_capacity += sgs->group_capacity; |
| |
| sg = sg->next; |
| } while (sg != env->sd->groups); |
| |
| if (env->sd->flags & SD_NUMA) |
| env->fbq_type = fbq_classify_group(&sds->busiest_stat); |
| |
| env->src_grp_nr_running = sds->busiest_stat.sum_nr_running; |
| |
| if (!env->sd->parent) { |
| /* update overload indicator if we are at root domain */ |
| if (env->dst_rq->rd->overload != overload) |
| env->dst_rq->rd->overload = overload; |
| |
| /* Update over-utilization (tipping point, U >= 0) indicator */ |
| if (env->dst_rq->rd->overutilized != overutilized) { |
| env->dst_rq->rd->overutilized = overutilized; |
| trace_sched_overutilized(overutilized); |
| } |
| } else { |
| if (!env->dst_rq->rd->overutilized && overutilized) { |
| env->dst_rq->rd->overutilized = true; |
| trace_sched_overutilized(true); |
| } |
| } |
| |
| } |
| |
| /** |
| * check_asym_packing - Check to see if the group is packed into the |
| * sched doman. |
| * |
| * This is primarily intended to used at the sibling level. Some |
| * cores like POWER7 prefer to use lower numbered SMT threads. In the |
| * case of POWER7, it can move to lower SMT modes only when higher |
| * threads are idle. When in lower SMT modes, the threads will |
| * perform better since they share less core resources. Hence when we |
| * have idle threads, we want them to be the higher ones. |
| * |
| * This packing function is run on idle threads. It checks to see if |
| * the busiest CPU in this domain (core in the P7 case) has a higher |
| * CPU number than the packing function is being run on. Here we are |
| * assuming lower CPU number will be equivalent to lower a SMT thread |
| * number. |
| * |
| * Return: 1 when packing is required and a task should be moved to |
| * this CPU. The amount of the imbalance is returned in *imbalance. |
| * |
| * @env: The load balancing environment. |
| * @sds: Statistics of the sched_domain which is to be packed |
| */ |
| static int check_asym_packing(struct lb_env *env, struct sd_lb_stats *sds) |
| { |
| int busiest_cpu; |
| |
| if (!(env->sd->flags & SD_ASYM_PACKING)) |
| return 0; |
| |
| if (env->idle == CPU_NOT_IDLE) |
| return 0; |
| |
| if (!sds->busiest) |
| return 0; |
| |
| busiest_cpu = group_first_cpu(sds->busiest); |
| if (env->dst_cpu > busiest_cpu) |
| return 0; |
| |
| env->imbalance = DIV_ROUND_CLOSEST( |
| sds->busiest_stat.avg_load * sds->busiest_stat.group_capacity, |
| SCHED_CAPACITY_SCALE); |
| |
| return 1; |
| } |
| |
| /** |
| * fix_small_imbalance - Calculate the minor imbalance that exists |
| * amongst the groups of a sched_domain, during |
| * load balancing. |
| * @env: The load balancing environment. |
| * @sds: Statistics of the sched_domain whose imbalance is to be calculated. |
| */ |
| static inline |
| void fix_small_imbalance(struct lb_env *env, struct sd_lb_stats *sds) |
| { |
| unsigned long tmp, capa_now = 0, capa_move = 0; |
| unsigned int imbn = 2; |
| unsigned long scaled_busy_load_per_task; |
| struct sg_lb_stats *local, *busiest; |
| |
| local = &sds->local_stat; |
| busiest = &sds->busiest_stat; |
| |
| if (!local->sum_nr_running) |
| local->load_per_task = cpu_avg_load_per_task(env->dst_cpu); |
| else if (busiest->load_per_task > local->load_per_task) |
| imbn = 1; |
| |
| scaled_busy_load_per_task = |
| (busiest->load_per_task * SCHED_CAPACITY_SCALE) / |
| busiest->group_capacity; |
| |
| if (busiest->avg_load + scaled_busy_load_per_task >= |
| local->avg_load + (scaled_busy_load_per_task * imbn)) { |
| env->imbalance = busiest->load_per_task; |
| return; |
| } |
| |
| /* |
| * OK, we don't have enough imbalance to justify moving tasks, |
| * however we may be able to increase total CPU capacity used by |
| * moving them. |
| */ |
| |
| capa_now += busiest->group_capacity * |
| min(busiest->load_per_task, busiest->avg_load); |
| capa_now += local->group_capacity * |
| min(local->load_per_task, local->avg_load); |
| capa_now /= SCHED_CAPACITY_SCALE; |
| |
| /* Amount of load we'd subtract */ |
| if (busiest->avg_load > scaled_busy_load_per_task) { |
| capa_move += busiest->group_capacity * |
| min(busiest->load_per_task, |
| busiest->avg_load - scaled_busy_load_per_task); |
| } |
| |
| /* Amount of load we'd add */ |
| if (busiest->avg_load * busiest->group_capacity < |
| busiest->load_per_task * SCHED_CAPACITY_SCALE) { |
| tmp = (busiest->avg_load * busiest->group_capacity) / |
| local->group_capacity; |
| } else { |
| tmp = (busiest->load_per_task * SCHED_CAPACITY_SCALE) / |
| local->group_capacity; |
| } |
| capa_move += local->group_capacity * |
| min(local->load_per_task, local->avg_load + tmp); |
| capa_move /= SCHED_CAPACITY_SCALE; |
| |
| /* Move if we gain throughput */ |
| if (capa_move > capa_now) |
| env->imbalance = busiest->load_per_task; |
| } |
| |
| /** |
| * calculate_imbalance - Calculate the amount of imbalance present within the |
| * groups of a given sched_domain during load balance. |
| * @env: load balance environment |
| * @sds: statistics of the sched_domain whose imbalance is to be calculated. |
| */ |
| static inline void calculate_imbalance(struct lb_env *env, struct sd_lb_stats *sds) |
| { |
| unsigned long max_pull, load_above_capacity = ~0UL; |
| struct sg_lb_stats *local, *busiest; |
| |
| local = &sds->local_stat; |
| busiest = &sds->busiest_stat; |
| |
| if (busiest->group_type == group_imbalanced) { |
| /* |
| * In the group_imb case we cannot rely on group-wide averages |
| * to ensure cpu-load equilibrium, look at wider averages. XXX |
| */ |
| busiest->load_per_task = |
| min(busiest->load_per_task, sds->avg_load); |
| } |
| |
| /* |
| * Avg load of busiest sg can be less and avg load of local sg can |
| * be greater than avg load across all sgs of sd because avg load |
| * factors in sg capacity and sgs with smaller group_type are |
| * skipped when updating the busiest sg: |
| */ |
| if (busiest->avg_load <= sds->avg_load || |
| local->avg_load >= sds->avg_load) { |
| env->imbalance = 0; |
| return fix_small_imbalance(env, sds); |
| } |
| |
| /* |
| * If there aren't any idle cpus, avoid creating some. |
| */ |
| if (busiest->group_type == group_overloaded && |
| local->group_type == group_overloaded) { |
| load_above_capacity = busiest->sum_nr_running * SCHED_CAPACITY_SCALE; |
| if (load_above_capacity > busiest->group_capacity) { |
| load_above_capacity -= busiest->group_capacity; |
| load_above_capacity *= scale_load_down(NICE_0_LOAD); |
| load_above_capacity /= busiest->group_capacity; |
| } else |
| load_above_capacity = ~0UL; |
| } |
| |
| /* |
| * We're trying to get all the cpus to the average_load, so we don't |
| * want to push ourselves above the average load, nor do we wish to |
| * reduce the max loaded cpu below the average load. At the same time, |
| * we also don't want to reduce the group load below the group |
| * capacity. Thus we look for the minimum possible imbalance. |
| */ |
| max_pull = min(busiest->avg_load - sds->avg_load, load_above_capacity); |
| |
| /* How much load to actually move to equalise the imbalance */ |
| env->imbalance = min( |
| max_pull * busiest->group_capacity, |
| (sds->avg_load - local->avg_load) * local->group_capacity |
| ) / SCHED_CAPACITY_SCALE; |
| |
| /* |
| * if *imbalance is less than the average load per runnable task |
| * there is no guarantee that any tasks will be moved so we'll have |
| * a think about bumping its value to force at least one task to be |
| * moved |
| */ |
| if (env->imbalance < busiest->load_per_task) |
| return fix_small_imbalance(env, sds); |
| } |
| |
| /******* find_busiest_group() helpers end here *********************/ |
| |
| /** |
| * find_busiest_group - Returns the busiest group within the sched_domain |
| * if there is an imbalance. |
| * |
| * Also calculates the amount of weighted load which should be moved |
| * to restore balance. |
| * |
| * @env: The load balancing environment. |
| * |
| * Return: - The busiest group if imbalance exists. |
| */ |
| static struct sched_group *find_busiest_group(struct lb_env *env) |
| { |
| struct sg_lb_stats *local, *busiest; |
| struct sd_lb_stats sds; |
| |
| init_sd_lb_stats(&sds); |
| |
| /* |
| * Compute the various statistics relavent for load balancing at |
| * this level. |
| */ |
| update_sd_lb_stats(env, &sds); |
| |
| if (energy_aware() && !env->dst_rq->rd->overutilized) |
| goto out_balanced; |
| |
| local = &sds.local_stat; |
| busiest = &sds.busiest_stat; |
| |
| /* ASYM feature bypasses nice load balance check */ |
| if (check_asym_packing(env, &sds)) |
| return sds.busiest; |
| |
| /* There is no busy sibling group to pull tasks from */ |
| if (!sds.busiest || busiest->sum_nr_running == 0) |
| goto out_balanced; |
| |
| if (env->flags & LBF_BIG_TASK_ACTIVE_BALANCE) |
| goto force_balance; |
| |
| if (bail_inter_cluster_balance(env, &sds)) |
| goto out_balanced; |
| |
| sds.avg_load = (SCHED_CAPACITY_SCALE * sds.total_load) |
| / sds.total_capacity; |
| |
| /* |
| * If the busiest group is imbalanced the below checks don't |
| * work because they assume all things are equal, which typically |
| * isn't true due to cpus_allowed constraints and the like. |
| */ |
| if (busiest->group_type == group_imbalanced) |
| goto force_balance; |
| |
| /* SD_BALANCE_NEWIDLE trumps SMP nice when underutilized */ |
| if (env->idle == CPU_NEWLY_IDLE && group_has_capacity(env, local) && |
| busiest->group_no_capacity) |
| goto force_balance; |
| |
| /* |
| * If the local group is busier than the selected busiest group |
| * don't try and pull any tasks. |
| */ |
| if (local->avg_load >= busiest->avg_load) |
| goto out_balanced; |
| |
| /* |
| * Don't pull any tasks if this group is already above the domain |
| * average load. |
| */ |
| if (local->avg_load >= sds.avg_load) |
| goto out_balanced; |
| |
| if (env->idle == CPU_IDLE) { |
| /* |
| * This cpu is idle. If the busiest group is not overloaded |
| * and there is no imbalance between this and busiest group |
| * wrt idle cpus, it is balanced. The imbalance becomes |
| * significant if the diff is greater than 1 otherwise we |
| * might end up to just move the imbalance on another group |
| */ |
| if ((busiest->group_type != group_overloaded) && |
| (local->idle_cpus <= (busiest->idle_cpus + 1))) |
| goto out_balanced; |
| } else { |
| /* |
| * In the CPU_NEWLY_IDLE, CPU_NOT_IDLE cases, use |
| * imbalance_pct to be conservative. |
| */ |
| if (100 * busiest->avg_load <= |
| env->sd->imbalance_pct * local->avg_load) |
| goto out_balanced; |
| } |
| |
| force_balance: |
| /* Looks like there is an imbalance. Compute it */ |
| calculate_imbalance(env, &sds); |
| return sds.busiest; |
| |
| out_balanced: |
| env->imbalance = 0; |
| return NULL; |
| } |
| |
| /* |
| * find_busiest_queue - find the busiest runqueue among the cpus in group. |
| */ |
| static struct rq *find_busiest_queue(struct lb_env *env, |
| struct sched_group *group) |
| { |
| struct rq *busiest = NULL, *rq; |
| unsigned long busiest_load = 0, busiest_capacity = 1; |
| int i; |
| |
| #ifdef CONFIG_SCHED_HMP |
| return find_busiest_queue_hmp(env, group); |
| #endif |
| |
| for_each_cpu_and(i, sched_group_cpus(group), env->cpus) { |
| unsigned long capacity, wl; |
| enum fbq_type rt; |
| |
| rq = cpu_rq(i); |
| rt = fbq_classify_rq(rq); |
| |
| /* |
| * We classify groups/runqueues into three groups: |
| * - regular: there are !numa tasks |
| * - remote: there are numa tasks that run on the 'wrong' node |
| * - all: there is no distinction |
| * |
| * In order to avoid migrating ideally placed numa tasks, |
| * ignore those when there's better options. |
| * |
| * If we ignore the actual busiest queue to migrate another |
| * task, the next balance pass can still reduce the busiest |
| * queue by moving tasks around inside the node. |
| * |
| * If we cannot move enough load due to this classification |
| * the next pass will adjust the group classification and |
| * allow migration of more tasks. |
| * |
| * Both cases only affect the total convergence complexity. |
| */ |
| if (rt > env->fbq_type) |
| continue; |
| |
| capacity = capacity_of(i); |
| |
| wl = weighted_cpuload(i); |
| |
| /* |
| * When comparing with imbalance, use weighted_cpuload() |
| * which is not scaled with the cpu capacity. |
| */ |
| |
| if (rq->nr_running == 1 && wl > env->imbalance && |
| !check_cpu_capacity(rq, env->sd)) |
| continue; |
| |
| /* |
| * For the load comparisons with the other cpu's, consider |
| * the weighted_cpuload() scaled with the cpu capacity, so |
| * that the load can be moved away from the cpu that is |
| * potentially running at a lower capacity. |
| * |
| * Thus we're looking for max(wl_i / capacity_i), crosswise |
| * multiplication to rid ourselves of the division works out |
| * to: wl_i * capacity_j > wl_j * capacity_i; where j is |
| * our previous maximum. |
| */ |
| if (wl * busiest_capacity > busiest_load * capacity) { |
| busiest_load = wl; |
| busiest_capacity = capacity; |
| busiest = rq; |
| } |
| } |
| |
| return busiest; |
| } |
| |
| /* |
| * Max backoff if we encounter pinned tasks. Pretty arbitrary value, but |
| * so long as it is large enough. |
| */ |
| #define MAX_PINNED_INTERVAL 16 |
| #define NEED_ACTIVE_BALANCE_THRESHOLD 10 |
| |
| static int need_active_balance(struct lb_env *env) |
| { |
| struct sched_domain *sd = env->sd; |
| |
| if (env->flags & LBF_BIG_TASK_ACTIVE_BALANCE) |
| return 1; |
| |
| if (env->idle == CPU_NEWLY_IDLE) { |
| |
| /* |
| * ASYM_PACKING needs to force migrate tasks from busy but |
| * higher numbered CPUs in order to pack all tasks in the |
| * lowest numbered CPUs. |
| */ |
| if ((sd->flags & SD_ASYM_PACKING) && env->src_cpu > env->dst_cpu) |
| return 1; |
| } |
| |
| /* |
| * The dst_cpu is idle and the src_cpu CPU has only 1 CFS task. |
| * It's worth migrating the task if the src_cpu's capacity is reduced |
| * because of other sched_class or IRQs if more capacity stays |
| * available on dst_cpu. |
| */ |
| if ((env->idle != CPU_NOT_IDLE) && |
| (env->src_rq->cfs.h_nr_running == 1)) { |
| if ((check_cpu_capacity(env->src_rq, sd)) && |
| (capacity_of(env->src_cpu)*sd->imbalance_pct < capacity_of(env->dst_cpu)*100)) |
| return 1; |
| } |
| |
| if (energy_aware() && (capacity_of(env->src_cpu) < capacity_of(env->dst_cpu)) && |
| env->src_rq->cfs.h_nr_running == 1 && |
| cpu_overutilized(env->src_cpu) && |
| !cpu_overutilized(env->dst_cpu)) { |
| return 1; |
| } |
| |
| return unlikely(sd->nr_balance_failed > |
| sd->cache_nice_tries + NEED_ACTIVE_BALANCE_THRESHOLD); |
| } |
| |
| static int group_balance_cpu_not_isolated(struct sched_group *sg) |
| { |
| cpumask_t cpus; |
| |
| cpumask_and(&cpus, sched_group_cpus(sg), sched_group_mask(sg)); |
| cpumask_andnot(&cpus, &cpus, cpu_isolated_mask); |
| return cpumask_first(&cpus); |
| } |
| |
| static int active_load_balance_cpu_stop(void *data); |
| |
| static int should_we_balance(struct lb_env *env) |
| { |
| struct sched_group *sg = env->sd->groups; |
| struct cpumask *sg_cpus, *sg_mask; |
| int cpu, balance_cpu = -1; |
| |
| /* |
| * In the newly idle case, we will allow all the cpu's |
| * to do the newly idle load balance. |
| */ |
| if (env->idle == CPU_NEWLY_IDLE) |
| return 1; |
| |
| sg_cpus = sched_group_cpus(sg); |
| sg_mask = sched_group_mask(sg); |
| /* Try to find first idle cpu */ |
| for_each_cpu_and(cpu, sg_cpus, env->cpus) { |
| if (!cpumask_test_cpu(cpu, sg_mask) || !idle_cpu(cpu) || |
| cpu_isolated(cpu)) |
| continue; |
| |
| balance_cpu = cpu; |
| break; |
| } |
| |
| if (balance_cpu == -1) |
| balance_cpu = group_balance_cpu_not_isolated(sg); |
| |
| /* |
| * First idle cpu or the first cpu(busiest) in this sched group |
| * is eligible for doing load balancing at this and above domains. |
| */ |
| return balance_cpu == env->dst_cpu; |
| } |
| |
| /* |
| * Check this_cpu to ensure it is balanced within domain. Attempt to move |
| * tasks if there is an imbalance. |
| */ |
| static int load_balance(int this_cpu, struct rq *this_rq, |
| struct sched_domain *sd, enum cpu_idle_type idle, |
| int *continue_balancing) |
| { |
| int ld_moved = 0, cur_ld_moved, active_balance = 0; |
| struct sched_domain *sd_parent = sd->parent; |
| struct sched_group *group = NULL; |
| struct rq *busiest = NULL; |
| unsigned long flags; |
| struct cpumask *cpus = this_cpu_cpumask_var_ptr(load_balance_mask); |
| |
| struct lb_env env = { |
| .sd = sd, |
| .dst_cpu = this_cpu, |
| .dst_rq = this_rq, |
| .dst_grpmask = sched_group_cpus(sd->groups), |
| .idle = idle, |
| .loop_break = sched_nr_migrate_break, |
| .cpus = cpus, |
| .fbq_type = all, |
| .tasks = LIST_HEAD_INIT(env.tasks), |
| .imbalance = 0, |
| .flags = 0, |
| .loop = 0, |
| .busiest_nr_running = 0, |
| .busiest_grp_capacity = 0, |
| .boost_policy = sched_boost_policy(), |
| }; |
| |
| /* |
| * For NEWLY_IDLE load_balancing, we don't need to consider |
| * other cpus in our group |
| */ |
| if (idle == CPU_NEWLY_IDLE) |
| env.dst_grpmask = NULL; |
| |
| cpumask_copy(cpus, cpu_active_mask); |
| |
| schedstat_inc(sd->lb_count[idle]); |
| |
| redo: |
| if (!should_we_balance(&env)) { |
| *continue_balancing = 0; |
| goto out_balanced; |
| } |
| |
| group = find_busiest_group(&env); |
| if (!group) { |
| schedstat_inc(sd->lb_nobusyg[idle]); |
| goto out_balanced; |
| } |
| |
| busiest = find_busiest_queue(&env, group); |
| if (!busiest) { |
| schedstat_inc(sd->lb_nobusyq[idle]); |
| goto out_balanced; |
| } |
| |
| BUG_ON(busiest == env.dst_rq); |
| |
| schedstat_add(sd->lb_imbalance[idle], env.imbalance); |
| |
| env.src_cpu = busiest->cpu; |
| env.src_rq = busiest; |
| |
| ld_moved = 0; |
| if (busiest->nr_running > 1) { |
| /* |
| * Attempt to move tasks. If find_busiest_group has found |
| * an imbalance but busiest->nr_running <= 1, the group is |
| * still unbalanced. ld_moved simply stays zero, so it is |
| * correctly treated as an imbalance. |
| */ |
| env.flags |= LBF_ALL_PINNED; |
| env.loop_max = min(sysctl_sched_nr_migrate, busiest->nr_running); |
| |
| more_balance: |
| raw_spin_lock_irqsave(&busiest->lock, flags); |
| |
| /* The world might have changed. Validate assumptions */ |
| if (busiest->nr_running <= 1) { |
| raw_spin_unlock_irqrestore(&busiest->lock, flags); |
| env.flags &= ~LBF_ALL_PINNED; |
| goto no_move; |
| } |
| |
| /* |
| * cur_ld_moved - load moved in current iteration |
| * ld_moved - cumulative load moved across iterations |
| */ |
| cur_ld_moved = detach_tasks(&env); |
| /* |
| * We want to potentially lower env.src_cpu's OPP. |
| */ |
| if (cur_ld_moved) |
| update_capacity_of(env.src_cpu); |
| |
| /* |
| * We've detached some tasks from busiest_rq. Every |
| * task is masked "TASK_ON_RQ_MIGRATING", so we can safely |
| * unlock busiest->lock, and we are able to be sure |
| * that nobody can manipulate the tasks in parallel. |
| * See task_rq_lock() family for the details. |
| */ |
| |
| raw_spin_unlock(&busiest->lock); |
| |
| if (cur_ld_moved) { |
| attach_tasks(&env); |
| ld_moved += cur_ld_moved; |
| } |
| |
| local_irq_restore(flags); |
| |
| if (env.flags & LBF_NEED_BREAK) { |
| env.flags &= ~LBF_NEED_BREAK; |
| goto more_balance; |
| } |
| |
| /* |
| * Revisit (affine) tasks on src_cpu that couldn't be moved to |
| * us and move them to an alternate dst_cpu in our sched_group |
| * where they can run. The upper limit on how many times we |
| * iterate on same src_cpu is dependent on number of cpus in our |
| * sched_group. |
| * |
| * This changes load balance semantics a bit on who can move |
| * load to a given_cpu. In addition to the given_cpu itself |
| * (or a ilb_cpu acting on its behalf where given_cpu is |
| * nohz-idle), we now have balance_cpu in a position to move |
| * load to given_cpu. In rare situations, this may cause |
| * conflicts (balance_cpu and given_cpu/ilb_cpu deciding |
| * _independently_ and at _same_ time to move some load to |
| * given_cpu) causing exceess load to be moved to given_cpu. |
| * This however should not happen so much in practice and |
| * moreover subsequent load balance cycles should correct the |
| * excess load moved. |
| */ |
| if ((env.flags & LBF_DST_PINNED) && env.imbalance > 0) { |
| |
| /* Prevent to re-select dst_cpu via env's cpus */ |
| cpumask_clear_cpu(env.dst_cpu, env.cpus); |
| |
| env.dst_rq = cpu_rq(env.new_dst_cpu); |
| env.dst_cpu = env.new_dst_cpu; |
| env.flags &= ~LBF_DST_PINNED; |
| env.loop = 0; |
| env.loop_break = sched_nr_migrate_break; |
| |
| /* |
| * Go back to "more_balance" rather than "redo" since we |
| * need to continue with same src_cpu. |
| */ |
| goto more_balance; |
| } |
| |
| /* |
| * We failed to reach balance because of affinity. |
| */ |
| if (sd_parent) { |
| int *group_imbalance = &sd_parent->groups->sgc->imbalance; |
| |
| if ((env.flags & LBF_SOME_PINNED) && env.imbalance > 0) |
| *group_imbalance = 1; |
| } |
| |
| /* All tasks on this runqueue were pinned by CPU affinity */ |
| if (unlikely(env.flags & LBF_ALL_PINNED)) { |
| cpumask_clear_cpu(cpu_of(busiest), cpus); |
| if (!cpumask_empty(cpus)) { |
| env.loop = 0; |
| env.loop_break = sched_nr_migrate_break; |
| goto redo; |
| } |
| goto out_all_pinned; |
| } |
| } |
| |
| no_move: |
| if (!ld_moved) { |
| if (!(env.flags & LBF_BIG_TASK_ACTIVE_BALANCE)) |
| schedstat_inc(sd->lb_failed[idle]); |
| /* |
| * Increment the failure counter only on periodic balance. |
| * We do not want newidle balance, which can be very |
| * frequent, pollute the failure counter causing |
| * excessive cache_hot migrations and active balances. |
| */ |
| if (idle != CPU_NEWLY_IDLE && |
| !(env.flags & LBF_BIG_TASK_ACTIVE_BALANCE)) { |
| if (env.src_grp_nr_running > 1) |
| sd->nr_balance_failed++; |
| } |
| |
| if (need_active_balance(&env)) { |
| raw_spin_lock_irqsave(&busiest->lock, flags); |
| |
| /* don't kick the active_load_balance_cpu_stop, |
| * if the curr task on busiest cpu can't be |
| * moved to this_cpu |
| */ |
| if (!cpumask_test_cpu(this_cpu, |
| tsk_cpus_allowed(busiest->curr))) { |
| raw_spin_unlock_irqrestore(&busiest->lock, |
| flags); |
| env.flags |= LBF_ALL_PINNED; |
| goto out_one_pinned; |
| } |
| |
| /* |
| * ->active_balance synchronizes accesses to |
| * ->active_balance_work. Once set, it's cleared |
| * only after active load balance is finished. |
| */ |
| if (!busiest->active_balance && |
| !cpu_isolated(cpu_of(busiest))) { |
| busiest->active_balance = 1; |
| busiest->push_cpu = this_cpu; |
| active_balance = 1; |
| } |
| raw_spin_unlock_irqrestore(&busiest->lock, flags); |
| |
| if (active_balance) { |
| stop_one_cpu_nowait(cpu_of(busiest), |
| active_load_balance_cpu_stop, busiest, |
| &busiest->active_balance_work); |
| *continue_balancing = 0; |
| } |
| |
| /* We've kicked active balancing, force task migration. */ |
| sd->nr_balance_failed = sd->cache_nice_tries + |
| NEED_ACTIVE_BALANCE_THRESHOLD - 1; |
| } |
| } else { |
| sd->nr_balance_failed = 0; |
| |
| /* Assumes one 'busiest' cpu that we pulled tasks from */ |
| if (!same_freq_domain(this_cpu, cpu_of(busiest))) { |
| int check_groups = !!(env.flags & |
| LBF_MOVED_RELATED_THREAD_GROUP_TASK); |
| |
| check_for_freq_change(this_rq, false, check_groups); |
| check_for_freq_change(busiest, false, check_groups); |
| } else { |
| check_for_freq_change(this_rq, true, false); |
| } |
| } |
| |
| if (likely(!active_balance)) { |
| /* We were unbalanced, so reset the balancing interval */ |
| sd->balance_interval = sd->min_interval; |
| } else { |
| /* |
| * If we've begun active balancing, start to back off. This |
| * case may not be covered by the all_pinned logic if there |
| * is only 1 task on the busy runqueue (because we don't call |
| * detach_tasks). |
| */ |
| if (sd->balance_interval < sd->max_interval) |
| sd->balance_interval *= 2; |
| } |
| |
| goto out; |
| |
| out_balanced: |
| /* |
| * We reach balance although we may have faced some affinity |
| * constraints. Clear the imbalance flag if it was set. |
| */ |
| if (sd_parent) { |
| int *group_imbalance = &sd_parent->groups->sgc->imbalance; |
| |
| if (*group_imbalance) |
| *group_imbalance = 0; |
| } |
| |
| out_all_pinned: |
| /* |
| * We reach balance because all tasks are pinned at this level so |
| * we can't migrate them. Let the imbalance flag set so parent level |
| * can try to migrate them. |
| */ |
| schedstat_inc(sd->lb_balanced[idle]); |
| |
| sd->nr_balance_failed = 0; |
| |
| out_one_pinned: |
| /* tune up the balancing interval */ |
| if (((env.flags & LBF_ALL_PINNED) && |
| sd->balance_interval < MAX_PINNED_INTERVAL) || |
| (sd->balance_interval < sd->max_interval)) |
| sd->balance_interval *= 2; |
| |
| ld_moved = 0; |
| out: |
| trace_sched_load_balance(this_cpu, idle, *continue_balancing, |
| group ? group->cpumask[0] : 0, |
| busiest ? busiest->nr_running : 0, |
| env.imbalance, env.flags, ld_moved, |
| sd->balance_interval); |
| return ld_moved; |
| } |
| |
| static inline unsigned long |
| get_sd_balance_interval(struct sched_domain *sd, int cpu_busy) |
| { |
| unsigned long interval = sd->balance_interval; |
| |
| if (cpu_busy) |
| interval *= sd->busy_factor; |
| |
| /* scale ms to jiffies */ |
| interval = msecs_to_jiffies(interval); |
| interval = clamp(interval, 1UL, max_load_balance_interval); |
| |
| return interval; |
| } |
| |
| static inline void |
| update_next_balance(struct sched_domain *sd, unsigned long *next_balance) |
| { |
| unsigned long interval, next; |
| |
| /* used by idle balance, so cpu_busy = 0 */ |
| interval = get_sd_balance_interval(sd, 0); |
| next = sd->last_balance + interval; |
| |
| if (time_after(*next_balance, next)) |
| *next_balance = next; |
| } |
| |
| /* |
| * idle_balance is called by schedule() if this_cpu is about to become |
| * idle. Attempts to pull tasks from other CPUs. |
| */ |
| static int idle_balance(struct rq *this_rq) |
| { |
| unsigned long next_balance = jiffies + HZ; |
| int this_cpu = this_rq->cpu; |
| struct sched_domain *sd; |
| int pulled_task = 0; |
| u64 curr_cost = 0; |
| long removed_util=0; |
| |
| if (cpu_isolated(this_cpu)) |
| return 0; |
| |
| /* |
| * We must set idle_stamp _before_ calling idle_balance(), such that we |
| * measure the duration of idle_balance() as idle time. |
| */ |
| this_rq->idle_stamp = rq_clock(this_rq); |
| |
| if (!energy_aware() && |
| (this_rq->avg_idle < sysctl_sched_migration_cost || |
| !this_rq->rd->overload)) { |
| rcu_read_lock(); |
| sd = rcu_dereference_check_sched_domain(this_rq->sd); |
| if (sd) |
| update_next_balance(sd, &next_balance); |
| rcu_read_unlock(); |
| |
| goto out; |
| } |
| |
| raw_spin_unlock(&this_rq->lock); |
| |
| /* |
| * If removed_util_avg is !0 we most probably migrated some task away |
| * from this_cpu. In this case we might be willing to trigger an OPP |
| * update, but we want to do so if we don't find anybody else to pull |
| * here (we will trigger an OPP update with the pulled task's enqueue |
| * anyway). |
| * |
| * Record removed_util before calling update_blocked_averages, and use |
| * it below (before returning) to see if an OPP update is required. |
| */ |
| removed_util = atomic_long_read(&(this_rq->cfs).removed_util_avg); |
| update_blocked_averages(this_cpu); |
| rcu_read_lock(); |
| for_each_domain(this_cpu, sd) { |
| int continue_balancing = 1; |
| u64 t0, domain_cost; |
| |
| if (!(sd->flags & SD_LOAD_BALANCE)) |
| continue; |
| |
| if (this_rq->avg_idle < curr_cost + sd->max_newidle_lb_cost) { |
| update_next_balance(sd, &next_balance); |
| break; |
| } |
| |
| if (sd->flags & SD_BALANCE_NEWIDLE) { |
| t0 = sched_clock_cpu(this_cpu); |
| |
| pulled_task = load_balance(this_cpu, this_rq, |
| sd, CPU_NEWLY_IDLE, |
| &continue_balancing); |
| |
| domain_cost = sched_clock_cpu(this_cpu) - t0; |
| if (domain_cost > sd->max_newidle_lb_cost) |
| sd->max_newidle_lb_cost = domain_cost; |
| |
| curr_cost += domain_cost; |
| } |
| |
| update_next_balance(sd, &next_balance); |
| |
| /* |
| * Stop searching for tasks to pull if there are |
| * now runnable tasks on the balance rq or if |
| * continue_balancing has been unset (only possible |
| * due to active migration). |
| */ |
| if (pulled_task || this_rq->nr_running > 0 || |
| !continue_balancing) |
| break; |
| } |
| rcu_read_unlock(); |
| |
| raw_spin_lock(&this_rq->lock); |
| |
| if (curr_cost > this_rq->max_idle_balance_cost) |
| this_rq->max_idle_balance_cost = curr_cost; |
| |
| /* |
| * While browsing the domains, we released the rq lock, a task could |
| * have been enqueued in the meantime. Since we're not going idle, |
| * pretend we pulled a task. |
| */ |
| if (this_rq->cfs.h_nr_running && !pulled_task) |
| pulled_task = 1; |
| |
| out: |
| /* Move the next balance forward */ |
| if (time_after(this_rq->next_balance, next_balance)) |
| this_rq->next_balance = next_balance; |
| |
| /* Is there a task of a high priority class? */ |
| if (this_rq->nr_running != this_rq->cfs.h_nr_running) |
| pulled_task = -1; |
| |
| if (pulled_task) |
| this_rq->idle_stamp = 0; |
| else if (removed_util) { |
| /* |
| * No task pulled and someone has been migrated away. |
| * Good case to trigger an OPP update. |
| */ |
| update_capacity_of(this_cpu); |
| } |
| |
| return pulled_task; |
| } |
| |
| /* |
| * active_load_balance_cpu_stop is run by cpu stopper. It pushes |
| * running tasks off the busiest CPU onto idle CPUs. It requires at |
| * least 1 task to be running on each physical CPU where possible, and |
| * avoids physical / logical imbalances. |
| */ |
| static int active_load_balance_cpu_stop(void *data) |
| { |
| struct rq *busiest_rq = data; |
| int busiest_cpu = cpu_of(busiest_rq); |
| int target_cpu = busiest_rq->push_cpu; |
| struct rq *target_rq = cpu_rq(target_cpu); |
| struct sched_domain *sd = NULL; |
| struct task_struct *p = NULL; |
| struct task_struct *push_task; |
| int push_task_detached = 0; |
| struct lb_env env = { |
| .sd = sd, |
| .dst_cpu = target_cpu, |
| .dst_rq = target_rq, |
| .src_cpu = busiest_rq->cpu, |
| .src_rq = busiest_rq, |
| .idle = CPU_IDLE, |
| .busiest_nr_running = 0, |
| .busiest_grp_capacity = 0, |
| .flags = 0, |
| .loop = 0, |
| .boost_policy = sched_boost_policy(), |
| }; |
| bool moved = false; |
| |
| raw_spin_lock_irq(&busiest_rq->lock); |
| |
| /* make sure the requested cpu hasn't gone down in the meantime */ |
| if (unlikely(busiest_cpu != smp_processor_id() || |
| !busiest_rq->active_balance)) |
| goto out_unlock; |
| |
| /* Is there any task to move? */ |
| if (busiest_rq->nr_running <= 1) |
| goto out_unlock; |
| |
| /* |
| * This condition is "impossible", if it occurs |
| * we need to fix it. Originally reported by |
| * Bjorn Helgaas on a 128-cpu setup. |
| */ |
| BUG_ON(busiest_rq == target_rq); |
| |
| push_task = busiest_rq->push_task; |
| target_cpu = busiest_rq->push_cpu; |
| if (push_task) { |
| if (task_on_rq_queued(push_task) && |
| push_task->state == TASK_RUNNING && |
| task_cpu(push_task) == busiest_cpu && |
| cpu_online(target_cpu)) { |
| detach_task(push_task, &env); |
| push_task_detached = 1; |
| moved = true; |
| } |
| goto out_unlock; |
| } |
| |
| /* Search for an sd spanning us and the target CPU. */ |
| rcu_read_lock(); |
| for_each_domain(target_cpu, sd) { |
| if ((sd->flags & SD_LOAD_BALANCE) && |
| cpumask_test_cpu(busiest_cpu, sched_domain_span(sd))) |
| break; |
| } |
| |
| if (likely(sd)) { |
| env.sd = sd; |
| schedstat_inc(sd->alb_count); |
| |
| p = detach_one_task(&env); |
| if (p) { |
| schedstat_inc(sd->alb_pushed); |
| /* |
| * We want to potentially lower env.src_cpu's OPP. |
| */ |
| update_capacity_of(env.src_cpu); |
| /* Active balancing done, reset the failure counter. */ |
| sd->nr_balance_failed = 0; |
| moved = true; |
| } else { |
| schedstat_inc(sd->alb_failed); |
| } |
| } |
| rcu_read_unlock(); |
| out_unlock: |
| busiest_rq->active_balance = 0; |
| push_task = busiest_rq->push_task; |
| target_cpu = busiest_rq->push_cpu; |
| |
| if (push_task) |
| busiest_rq->push_task = NULL; |
| |
| raw_spin_unlock(&busiest_rq->lock); |
| |
| if (push_task) { |
| if (push_task_detached) |
| attach_one_task(target_rq, push_task); |
| put_task_struct(push_task); |
| clear_reserved(target_cpu); |
| } |
| |
| if (p) |
| attach_one_task(target_rq, p); |
| |
| local_irq_enable(); |
| |
| if (moved && !same_freq_domain(busiest_cpu, target_cpu)) { |
| int check_groups = !!(env.flags & |
| LBF_MOVED_RELATED_THREAD_GROUP_TASK); |
| check_for_freq_change(busiest_rq, false, check_groups); |
| check_for_freq_change(target_rq, false, check_groups); |
| } else if (moved) { |
| check_for_freq_change(target_rq, true, false); |
| } |
| |
| return 0; |
| } |
| |
| static inline int on_null_domain(struct rq *rq) |
| { |
| return unlikely(!rcu_dereference_sched(rq->sd)); |
| } |
| |
| #ifdef CONFIG_NO_HZ_COMMON |
| /* |
| * idle load balancing details |
| * - When one of the busy CPUs notice that there may be an idle rebalancing |
| * needed, they will kick the idle load balancer, which then does idle |
| * load balancing for all the idle CPUs. |
| */ |
| static struct { |
| cpumask_var_t idle_cpus_mask; |
| atomic_t nr_cpus; |
| unsigned long next_balance; /* in jiffy units */ |
| } nohz ____cacheline_aligned; |
| |
| static inline int find_new_ilb(int type) |
| { |
| int ilb = cpumask_first(nohz.idle_cpus_mask); |
| |
| #ifdef CONFIG_SCHED_HMP |
| return find_new_hmp_ilb(type); |
| #endif |
| |
| if (ilb < nr_cpu_ids && idle_cpu(ilb)) |
| return ilb; |
| |
| return nr_cpu_ids; |
| } |
| |
| /* |
| * Kick a CPU to do the nohz balancing, if it is time for it. We pick the |
| * nohz_load_balancer CPU (if there is one) otherwise fallback to any idle |
| * CPU (if there is one). |
| */ |
| static void nohz_balancer_kick(int type) |
| { |
| int ilb_cpu; |
| |
| nohz.next_balance++; |
| |
| ilb_cpu = find_new_ilb(type); |
| |
| if (ilb_cpu >= nr_cpu_ids) |
| return; |
| |
| if (test_and_set_bit(NOHZ_BALANCE_KICK, nohz_flags(ilb_cpu))) |
| return; |
| /* |
| * Use smp_send_reschedule() instead of resched_cpu(). |
| * This way we generate a sched IPI on the target cpu which |
| * is idle. And the softirq performing nohz idle load balance |
| * will be run before returning from the IPI. |
| */ |
| smp_send_reschedule(ilb_cpu); |
| return; |
| } |
| |
| void nohz_balance_clear_nohz_mask(int cpu) |
| { |
| if (likely(cpumask_test_cpu(cpu, nohz.idle_cpus_mask))) { |
| cpumask_clear_cpu(cpu, nohz.idle_cpus_mask); |
| atomic_dec(&nohz.nr_cpus); |
| } |
| } |
| |
| void nohz_balance_exit_idle(unsigned int cpu) |
| { |
| if (unlikely(test_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu)))) { |
| /* |
| * Completely isolated CPUs don't ever set, so we must test. |
| */ |
| nohz_balance_clear_nohz_mask(cpu); |
| clear_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu)); |
| } |
| } |
| |
| static inline void set_cpu_sd_state_busy(void) |
| { |
| struct sched_domain *sd; |
| int cpu = smp_processor_id(); |
| |
| rcu_read_lock(); |
| sd = rcu_dereference(per_cpu(sd_llc, cpu)); |
| |
| if (!sd || !sd->nohz_idle) |
| goto unlock; |
| sd->nohz_idle = 0; |
| |
| atomic_inc(&sd->shared->nr_busy_cpus); |
| unlock: |
| rcu_read_unlock(); |
| } |
| |
| void set_cpu_sd_state_idle(void) |
| { |
| struct sched_domain *sd; |
| int cpu = smp_processor_id(); |
| |
| rcu_read_lock(); |
| sd = rcu_dereference(per_cpu(sd_llc, cpu)); |
| |
| if (!sd || sd->nohz_idle) |
| goto unlock; |
| sd->nohz_idle = 1; |
| |
| atomic_dec(&sd->shared->nr_busy_cpus); |
| unlock: |
| rcu_read_unlock(); |
| } |
| |
| /* |
| * This routine will record that the cpu is going idle with tick stopped. |
| * This info will be used in performing idle load balancing in the future. |
| */ |
| void nohz_balance_enter_idle(int cpu) |
| { |
| /* |
| * If this cpu is going down, then nothing needs to be done. |
| */ |
| if (!cpu_active(cpu)) |
| return; |
| |
| if (test_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu))) |
| return; |
| |
| /* |
| * If we're a completely isolated CPU, we don't play. |
| */ |
| if (on_null_domain(cpu_rq(cpu)) || cpu_isolated(cpu)) |
| return; |
| |
| cpumask_set_cpu(cpu, nohz.idle_cpus_mask); |
| atomic_inc(&nohz.nr_cpus); |
| set_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu)); |
| } |
| #endif |
| |
| static DEFINE_SPINLOCK(balancing); |
| |
| /* |
| * Scale the max load_balance interval with the number of CPUs in the system. |
| * This trades load-balance latency on larger machines for less cross talk. |
| */ |
| void update_max_interval(void) |
| { |
| cpumask_t avail_mask; |
| unsigned int available_cpus; |
| |
| cpumask_andnot(&avail_mask, cpu_online_mask, cpu_isolated_mask); |
| available_cpus = cpumask_weight(&avail_mask); |
| |
| max_load_balance_interval = HZ*available_cpus/10; |
| } |
| |
| /* |
| * It checks each scheduling domain to see if it is due to be balanced, |
| * and initiates a balancing operation if so. |
| * |
| * Balancing parameters are set up in init_sched_domains. |
| */ |
| static void rebalance_domains(struct rq *rq, enum cpu_idle_type idle) |
| { |
| int continue_balancing = 1; |
| int cpu = rq->cpu; |
| unsigned long interval; |
| struct sched_domain *sd; |
| /* Earliest time when we have to do rebalance again */ |
| unsigned long next_balance = jiffies + 60*HZ; |
| int update_next_balance = 0; |
| int need_serialize, need_decay = 0; |
| u64 max_cost = 0; |
| |
| update_blocked_averages(cpu); |
| |
| rcu_read_lock(); |
| for_each_domain(cpu, sd) { |
| /* |
| * Decay the newidle max times here because this is a regular |
| * visit to all the domains. Decay ~1% per second. |
| */ |
| if (time_after(jiffies, sd->next_decay_max_lb_cost)) { |
| sd->max_newidle_lb_cost = |
| (sd->max_newidle_lb_cost * 253) / 256; |
| sd->next_decay_max_lb_cost = jiffies + HZ; |
| need_decay = 1; |
| } |
| max_cost += sd->max_newidle_lb_cost; |
| |
| if (!(sd->flags & SD_LOAD_BALANCE)) |
| continue; |
| |
| /* |
| * Stop the load balance at this level. There is another |
| * CPU in our sched group which is doing load balancing more |
| * actively. |
| */ |
| if (!continue_balancing) { |
| if (need_decay) |
| continue; |
| break; |
| } |
| |
| interval = get_sd_balance_interval(sd, idle != CPU_IDLE); |
| |
| need_serialize = sd->flags & SD_SERIALIZE; |
| if (need_serialize) { |
| if (!spin_trylock(&balancing)) |
| goto out; |
| } |
| |
| if (time_after_eq(jiffies, sd->last_balance + interval)) { |
| if (load_balance(cpu, rq, sd, idle, &continue_balancing)) { |
| /* |
| * The LBF_DST_PINNED logic could have changed |
| * env->dst_cpu, so we can't know our idle |
| * state even if we migrated tasks. Update it. |
| */ |
| idle = idle_cpu(cpu) ? CPU_IDLE : CPU_NOT_IDLE; |
| } |
| sd->last_balance = jiffies; |
| interval = get_sd_balance_interval(sd, idle != CPU_IDLE); |
| } |
| if (need_serialize) |
| spin_unlock(&balancing); |
| out: |
| if (time_after(next_balance, sd->last_balance + interval)) { |
| next_balance = sd->last_balance + interval; |
| update_next_balance = 1; |
| } |
| } |
| if (need_decay) { |
| /* |
| * Ensure the rq-wide value also decays but keep it at a |
| * reasonable floor to avoid funnies with rq->avg_idle. |
| */ |
| rq->max_idle_balance_cost = |
| max((u64)sysctl_sched_migration_cost, max_cost); |
| } |
| rcu_read_unlock(); |
| |
| /* |
| * next_balance will be updated only when there is a need. |
| * When the cpu is attached to null domain for ex, it will not be |
| * updated. |
| */ |
| if (likely(update_next_balance)) { |
| rq->next_balance = next_balance; |
| |
| #ifdef CONFIG_NO_HZ_COMMON |
| /* |
| * If this CPU has been elected to perform the nohz idle |
| * balance. Other idle CPUs have already rebalanced with |
| * nohz_idle_balance() and nohz.next_balance has been |
| * updated accordingly. This CPU is now running the idle load |
| * balance for itself and we need to update the |
| * nohz.next_balance accordingly. |
| */ |
| if ((idle == CPU_IDLE) && time_after(nohz.next_balance, rq->next_balance)) |
| nohz.next_balance = rq->next_balance; |
| #endif |
| } |
| } |
| |
| #ifdef CONFIG_NO_HZ_COMMON |
| /* |
| * In CONFIG_NO_HZ_COMMON case, the idle balance kickee will do the |
| * rebalancing for all the cpus for whom scheduler ticks are stopped. |
| */ |
| static void nohz_idle_balance(struct rq *this_rq, enum cpu_idle_type idle) |
| { |
| int this_cpu = this_rq->cpu; |
| struct rq *rq; |
| int balance_cpu; |
| /* Earliest time when we have to do rebalance again */ |
| unsigned long next_balance = jiffies + 60*HZ; |
| int update_next_balance = 0; |
| cpumask_t cpus; |
| |
| if (idle != CPU_IDLE || |
| !test_bit(NOHZ_BALANCE_KICK, nohz_flags(this_cpu))) |
| goto end; |
| |
| cpumask_andnot(&cpus, nohz.idle_cpus_mask, cpu_isolated_mask); |
| |
| for_each_cpu(balance_cpu, &cpus) { |
| if (balance_cpu == this_cpu || !idle_cpu(balance_cpu)) |
| continue; |
| |
| /* |
| * If this cpu gets work to do, stop the load balancing |
| * work being done for other cpus. Next load |
| * balancing owner will pick it up. |
| */ |
| if (need_resched()) |
| break; |
| |
| rq = cpu_rq(balance_cpu); |
| |
| /* |
| * If time for next balance is due, |
| * do the balance. |
| */ |
| if (time_after_eq(jiffies, rq->next_balance)) { |
| raw_spin_lock_irq(&rq->lock); |
| update_rq_clock(rq); |
| cpu_load_update_idle(rq); |
| raw_spin_unlock_irq(&rq->lock); |
| rebalance_domains(rq, CPU_IDLE); |
| } |
| |
| if (time_after(next_balance, rq->next_balance)) { |
| next_balance = rq->next_balance; |
| update_next_balance = 1; |
| } |
| } |
| |
| /* |
| * next_balance will be updated only when there is a need. |
| * When the CPU is attached to null domain for ex, it will not be |
| * updated. |
| */ |
| if (likely(update_next_balance)) |
| nohz.next_balance = next_balance; |
| end: |
| clear_bit(NOHZ_BALANCE_KICK, nohz_flags(this_cpu)); |
| } |
| |
| /* |
| * Current heuristic for kicking the idle load balancer in the presence |
| * of an idle cpu in the system. |
| * - This rq has more than one task. |
| * - This rq has at least one CFS task and the capacity of the CPU is |
| * significantly reduced because of RT tasks or IRQs. |
| * - At parent of LLC scheduler domain level, this cpu's scheduler group has |
| * multiple busy cpu. |
| * - For SD_ASYM_PACKING, if the lower numbered cpu's in the scheduler |
| * domain span are idle. |
| */ |
| static inline bool nohz_kick_needed(struct rq *rq, int *type) |
| { |
| unsigned long now = jiffies; |
| #ifndef CONFIG_SCHED_HMP |
| struct sched_domain_shared *sds; |
| struct sched_domain *sd; |
| int nr_busy; |
| #endif |
| int cpu = rq->cpu; |
| bool kick = false; |
| |
| if (unlikely(rq->idle_balance)) |
| return false; |
| |
| /* |
| * We may be recently in ticked or tickless idle mode. At the first |
| * busy tick after returning from idle, we will update the busy stats. |
| */ |
| set_cpu_sd_state_busy(); |
| nohz_balance_exit_idle(cpu); |
| |
| /* |
| * None are in tickless mode and hence no need for NOHZ idle load |
| * balancing. |
| */ |
| if (likely(!atomic_read(&nohz.nr_cpus))) |
| return false; |
| |
| #ifdef CONFIG_SCHED_HMP |
| return _nohz_kick_needed_hmp(rq, cpu, type); |
| #endif |
| |
| if (time_before(now, nohz.next_balance)) |
| return false; |
| |
| if (rq->nr_running >= 2 && |
| (!energy_aware() || cpu_overutilized(cpu))) |
| return true; |
| |
| #ifndef CONFIG_SCHED_HMP |
| rcu_read_lock(); |
| sds = rcu_dereference(per_cpu(sd_llc_shared, cpu)); |
| if (sds && !energy_aware()) { |
| /* |
| * XXX: write a coherent comment on why we do this. |
| * See also: http://lkml.kernel.org/r/20111202010832.602203411@sbsiddha-desk.sc.intel.com |
| */ |
| nr_busy = atomic_read(&sds->nr_busy_cpus); |
| if (nr_busy > 1) { |
| kick = true; |
| goto unlock; |
| } |
| |
| } |
| |
| sd = rcu_dereference(rq->sd); |
| if (sd) { |
| if ((rq->cfs.h_nr_running >= 1) && |
| check_cpu_capacity(rq, sd)) { |
| kick = true; |
| goto unlock; |
| } |
| } |
| |
| sd = rcu_dereference(per_cpu(sd_asym, cpu)); |
| if (sd && (cpumask_first_and(nohz.idle_cpus_mask, |
| sched_domain_span(sd)) < cpu)) { |
| kick = true; |
| goto unlock; |
| } |
| |
| unlock: |
| rcu_read_unlock(); |
| #endif |
| return kick; |
| } |
| #else |
| static void nohz_idle_balance(struct rq *this_rq, enum cpu_idle_type idle) { } |
| #endif |
| |
| /* |
| * run_rebalance_domains is triggered when needed from the scheduler tick. |
| * Also triggered for nohz idle balancing (with nohz_balancing_kick set). |
| */ |
| static __latent_entropy void run_rebalance_domains(struct softirq_action *h) |
| { |
| struct rq *this_rq = this_rq(); |
| enum cpu_idle_type idle = this_rq->idle_balance ? |
| CPU_IDLE : CPU_NOT_IDLE; |
| |
| /* |
| * If this cpu has a pending nohz_balance_kick, then do the |
| * balancing on behalf of the other idle cpus whose ticks are |
| * stopped. Do nohz_idle_balance *before* rebalance_domains to |
| * give the idle cpus a chance to load balance. Else we may |
| * load balance only within the local sched_domain hierarchy |
| * and abort nohz_idle_balance altogether if we pull some load. |
| */ |
| nohz_idle_balance(this_rq, idle); |
| rebalance_domains(this_rq, idle); |
| } |
| |
| /* |
| * Trigger the SCHED_SOFTIRQ if it is time to do periodic load balancing. |
| */ |
| void trigger_load_balance(struct rq *rq) |
| { |
| int type = NOHZ_KICK_ANY; |
| |
| /* Don't need to rebalance while attached to NULL domain or |
| * cpu is isolated. |
| */ |
| if (unlikely(on_null_domain(rq)) || cpu_isolated(cpu_of(rq))) |
| return; |
| |
| if (time_after_eq(jiffies, rq->next_balance)) |
| raise_softirq(SCHED_SOFTIRQ); |
| #ifdef CONFIG_NO_HZ_COMMON |
| if (nohz_kick_needed(rq, &type)) |
| nohz_balancer_kick(type); |
| #endif |
| } |
| |
| static void rq_online_fair(struct rq *rq) |
| { |
| update_sysctl(); |
| |
| update_runtime_enabled(rq); |
| } |
| |
| static void rq_offline_fair(struct rq *rq) |
| { |
| update_sysctl(); |
| |
| /* Ensure any throttled groups are reachable by pick_next_task */ |
| unthrottle_offline_cfs_rqs(rq); |
| } |
| |
| #endif /* CONFIG_SMP */ |
| |
| /* |
| * scheduler tick hitting a task of our scheduling class: |
| */ |
| static void task_tick_fair(struct rq *rq, struct task_struct *curr, int queued) |
| { |
| struct cfs_rq *cfs_rq; |
| struct sched_entity *se = &curr->se; |
| |
| for_each_sched_entity(se) { |
| cfs_rq = cfs_rq_of(se); |
| entity_tick(cfs_rq, se, queued); |
| } |
| |
| if (static_branch_unlikely(&sched_numa_balancing)) |
| task_tick_numa(rq, curr); |
| |
| #ifdef CONFIG_SMP |
| if (!rq->rd->overutilized && cpu_overutilized(task_cpu(curr))) { |
| rq->rd->overutilized = true; |
| trace_sched_overutilized(true); |
| } |
| |
| rq->misfit_task = !task_fits_max(curr, rq->cpu); |
| #endif |
| |
| } |
| |
| /* |
| * called on fork with the child task as argument from the parent's context |
| * - child not yet on the tasklist |
| * - preemption disabled |
| */ |
| static void task_fork_fair(struct task_struct *p) |
| { |
| struct cfs_rq *cfs_rq; |
| struct sched_entity *se = &p->se, *curr; |
| struct rq *rq = this_rq(); |
| |
| raw_spin_lock(&rq->lock); |
| update_rq_clock(rq); |
| |
| cfs_rq = task_cfs_rq(current); |
| curr = cfs_rq->curr; |
| if (curr) { |
| update_curr(cfs_rq); |
| se->vruntime = curr->vruntime; |
| } |
| place_entity(cfs_rq, se, 1); |
| |
| if (sysctl_sched_child_runs_first && curr && entity_before(curr, se)) { |
| /* |
| * Upon rescheduling, sched_class::put_prev_task() will place |
| * 'current' within the tree based on its new key value. |
| */ |
| swap(curr->vruntime, se->vruntime); |
| resched_curr(rq); |
| } |
| |
| se->vruntime -= cfs_rq->min_vruntime; |
| raw_spin_unlock(&rq->lock); |
| } |
| |
| /* |
| * Priority of the task has changed. Check to see if we preempt |
| * the current task. |
| */ |
| static void |
| prio_changed_fair(struct rq *rq, struct task_struct *p, int oldprio) |
| { |
| if (!task_on_rq_queued(p)) |
| return; |
| |
| /* |
| * Reschedule if we are currently running on this runqueue and |
| * our priority decreased, or if we are not currently running on |
| * this runqueue and our priority is higher than the current's |
| */ |
| if (rq->curr == p) { |
| if (p->prio > oldprio) |
| resched_curr(rq); |
| } else |
| check_preempt_curr(rq, p, 0); |
| } |
| |
| static inline bool vruntime_normalized(struct task_struct *p) |
| { |
| struct sched_entity *se = &p->se; |
| |
| /* |
| * In both the TASK_ON_RQ_QUEUED and TASK_ON_RQ_MIGRATING cases, |
| * the dequeue_entity(.flags=0) will already have normalized the |
| * vruntime. |
| */ |
| if (p->on_rq) |
| return true; |
| |
| /* |
| * When !on_rq, vruntime of the task has usually NOT been normalized. |
| * But there are some cases where it has already been normalized: |
| * |
| * - A forked child which is waiting for being woken up by |
| * wake_up_new_task(). |
| * - A task which has been woken up by try_to_wake_up() and |
| * waiting for actually being woken up by sched_ttwu_pending(). |
| */ |
| if (!se->sum_exec_runtime || p->state == TASK_WAKING) |
| return true; |
| |
| return false; |
| } |
| |
| static void detach_task_cfs_rq(struct task_struct *p) |
| { |
| struct sched_entity *se = &p->se; |
| struct cfs_rq *cfs_rq = cfs_rq_of(se); |
| u64 now = cfs_rq_clock_task(cfs_rq); |
| |
| if (!vruntime_normalized(p)) { |
| /* |
| * Fix up our vruntime so that the current sleep doesn't |
| * cause 'unlimited' sleep bonus. |
| */ |
| place_entity(cfs_rq, se, 0); |
| se->vruntime -= cfs_rq->min_vruntime; |
| } |
| |
| /* Catch up with the cfs_rq and remove our load when we leave */ |
| update_cfs_rq_load_avg(now, cfs_rq, false); |
| detach_entity_load_avg(cfs_rq, se); |
| update_tg_load_avg(cfs_rq, false); |
| } |
| |
| static void attach_task_cfs_rq(struct task_struct *p) |
| { |
| struct sched_entity *se = &p->se; |
| struct cfs_rq *cfs_rq = cfs_rq_of(se); |
| u64 now = cfs_rq_clock_task(cfs_rq); |
| |
| #ifdef CONFIG_FAIR_GROUP_SCHED |
| /* |
| * Since the real-depth could have been changed (only FAIR |
| * class maintain depth value), reset depth properly. |
| */ |
| se->depth = se->parent ? se->parent->depth + 1 : 0; |
| #endif |
| |
| /* Synchronize task with its cfs_rq */ |
| update_cfs_rq_load_avg(now, cfs_rq, false); |
| attach_entity_load_avg(cfs_rq, se); |
| update_tg_load_avg(cfs_rq, false); |
| |
| if (!vruntime_normalized(p)) |
| se->vruntime += cfs_rq->min_vruntime; |
| } |
| |
| static void switched_from_fair(struct rq *rq, struct task_struct *p) |
| { |
| detach_task_cfs_rq(p); |
| } |
| |
| static void switched_to_fair(struct rq *rq, struct task_struct *p) |
| { |
| attach_task_cfs_rq(p); |
| |
| if (task_on_rq_queued(p)) { |
| /* |
| * We were most likely switched from sched_rt, so |
| * kick off the schedule if running, otherwise just see |
| * if we can still preempt the current task. |
| */ |
| if (rq->curr == p) |
| resched_curr(rq); |
| else |
| check_preempt_curr(rq, p, 0); |
| } |
| } |
| |
| /* Account for a task changing its policy or group. |
| * |
| * This routine is mostly called to set cfs_rq->curr field when a task |
| * migrates between groups/classes. |
| */ |
| static void set_curr_task_fair(struct rq *rq) |
| { |
| struct sched_entity *se = &rq->curr->se; |
| |
| for_each_sched_entity(se) { |
| struct cfs_rq *cfs_rq = cfs_rq_of(se); |
| |
| set_next_entity(cfs_rq, se); |
| /* ensure bandwidth has been allocated on our new cfs_rq */ |
| account_cfs_rq_runtime(cfs_rq, 0); |
| } |
| } |
| |
| void init_cfs_rq(struct cfs_rq *cfs_rq) |
| { |
| cfs_rq->tasks_timeline = RB_ROOT; |
| cfs_rq->min_vruntime = (u64)(-(1LL << 20)); |
| #ifndef CONFIG_64BIT |
| cfs_rq->min_vruntime_copy = cfs_rq->min_vruntime; |
| #endif |
| #ifdef CONFIG_SMP |
| atomic_long_set(&cfs_rq->removed_load_avg, 0); |
| atomic_long_set(&cfs_rq->removed_util_avg, 0); |
| #endif |
| } |
| |
| #ifdef CONFIG_FAIR_GROUP_SCHED |
| static void task_set_group_fair(struct task_struct *p) |
| { |
| struct sched_entity *se = &p->se; |
| |
| set_task_rq(p, task_cpu(p)); |
| se->depth = se->parent ? se->parent->depth + 1 : 0; |
| } |
| |
| static void task_move_group_fair(struct task_struct *p) |
| { |
| detach_task_cfs_rq(p); |
| set_task_rq(p, task_cpu(p)); |
| |
| #ifdef CONFIG_SMP |
| /* Tell se's cfs_rq has been changed -- migrated */ |
| p->se.avg.last_update_time = 0; |
| #endif |
| attach_task_cfs_rq(p); |
| } |
| |
| static void task_change_group_fair(struct task_struct *p, int type) |
| { |
| switch (type) { |
| case TASK_SET_GROUP: |
| task_set_group_fair(p); |
| break; |
| |
| case TASK_MOVE_GROUP: |
| task_move_group_fair(p); |
| break; |
| } |
| } |
| |
| void free_fair_sched_group(struct task_group *tg) |
| { |
| int i; |
| |
| destroy_cfs_bandwidth(tg_cfs_bandwidth(tg)); |
| |
| for_each_possible_cpu(i) { |
| if (tg->cfs_rq) |
| kfree(tg->cfs_rq[i]); |
| if (tg->se) |
| kfree(tg->se[i]); |
| } |
| |
| kfree(tg->cfs_rq); |
| kfree(tg->se); |
| } |
| |
| int alloc_fair_sched_group(struct task_group *tg, struct task_group *parent) |
| { |
| struct sched_entity *se; |
| struct cfs_rq *cfs_rq; |
| int i; |
| |
| tg->cfs_rq = kzalloc(sizeof(cfs_rq) * nr_cpu_ids, GFP_KERNEL); |
| if (!tg->cfs_rq) |
| goto err; |
| tg->se = kzalloc(sizeof(se) * nr_cpu_ids, GFP_KERNEL); |
| if (!tg->se) |
| goto err; |
| |
| tg->shares = NICE_0_LOAD; |
| |
| init_cfs_bandwidth(tg_cfs_bandwidth(tg)); |
| |
| for_each_possible_cpu(i) { |
| cfs_rq = kzalloc_node(sizeof(struct cfs_rq), |
| GFP_KERNEL, cpu_to_node(i)); |
| if (!cfs_rq) |
| goto err; |
| |
| se = kzalloc_node(sizeof(struct sched_entity), |
| GFP_KERNEL, cpu_to_node(i)); |
| if (!se) |
| goto err_free_rq; |
| |
| init_cfs_rq(cfs_rq); |
| init_tg_cfs_entry(tg, cfs_rq, se, i, parent->se[i]); |
| init_entity_runnable_average(se); |
| } |
| |
| return 1; |
| |
| err_free_rq: |
| kfree(cfs_rq); |
| err: |
| return 0; |
| } |
| |
| void online_fair_sched_group(struct task_group *tg) |
| { |
| struct sched_entity *se; |
| struct rq *rq; |
| int i; |
| |
| for_each_possible_cpu(i) { |
| rq = cpu_rq(i); |
| se = tg->se[i]; |
| |
| raw_spin_lock_irq(&rq->lock); |
| post_init_entity_util_avg(se); |
| sync_throttle(tg, i); |
| raw_spin_unlock_irq(&rq->lock); |
| } |
| } |
| |
| void unregister_fair_sched_group(struct task_group *tg) |
| { |
| unsigned long flags; |
| struct rq *rq; |
| int cpu; |
| |
| for_each_possible_cpu(cpu) { |
| if (tg->se[cpu]) |
| remove_entity_load_avg(tg->se[cpu]); |
| |
| /* |
| * Only empty task groups can be destroyed; so we can speculatively |
| * check on_list without danger of it being re-added. |
| */ |
| if (!tg->cfs_rq[cpu]->on_list) |
| continue; |
| |
| rq = cpu_rq(cpu); |
| |
| raw_spin_lock_irqsave(&rq->lock, flags); |
| list_del_leaf_cfs_rq(tg->cfs_rq[cpu]); |
| raw_spin_unlock_irqrestore(&rq->lock, flags); |
| } |
| } |
| |
| void init_tg_cfs_entry(struct task_group *tg, struct cfs_rq *cfs_rq, |
| struct sched_entity *se, int cpu, |
| struct sched_entity *parent) |
| { |
| struct rq *rq = cpu_rq(cpu); |
| |
| cfs_rq->tg = tg; |
| cfs_rq->rq = rq; |
| init_cfs_rq_runtime(cfs_rq); |
| |
| tg->cfs_rq[cpu] = cfs_rq; |
| tg->se[cpu] = se; |
| |
| /* se could be NULL for root_task_group */ |
| if (!se) |
| return; |
| |
| if (!parent) { |
| se->cfs_rq = &rq->cfs; |
| se->depth = 0; |
| } else { |
| se->cfs_rq = parent->my_q; |
| se->depth = parent->depth + 1; |
| } |
| |
| se->my_q = cfs_rq; |
| /* guarantee group entities always have weight */ |
| update_load_set(&se->load, NICE_0_LOAD); |
| se->parent = parent; |
| } |
| |
| static DEFINE_MUTEX(shares_mutex); |
| |
| int sched_group_set_shares(struct task_group *tg, unsigned long shares) |
| { |
| int i; |
| unsigned long flags; |
| |
| /* |
| * We can't change the weight of the root cgroup. |
| */ |
| if (!tg->se[0]) |
| return -EINVAL; |
| |
| shares = clamp(shares, scale_load(MIN_SHARES), scale_load(MAX_SHARES)); |
| |
| mutex_lock(&shares_mutex); |
| if (tg->shares == shares) |
| goto done; |
| |
| tg->shares = shares; |
| for_each_possible_cpu(i) { |
| struct rq *rq = cpu_rq(i); |
| struct sched_entity *se; |
| |
| se = tg->se[i]; |
| /* Propagate contribution to hierarchy */ |
| raw_spin_lock_irqsave(&rq->lock, flags); |
| |
| /* Possible calls to update_curr() need rq clock */ |
| update_rq_clock(rq); |
| for_each_sched_entity(se) |
| update_cfs_shares(group_cfs_rq(se)); |
| raw_spin_unlock_irqrestore(&rq->lock, flags); |
| } |
| |
| done: |
| mutex_unlock(&shares_mutex); |
| return 0; |
| } |
| #else /* CONFIG_FAIR_GROUP_SCHED */ |
| |
| void free_fair_sched_group(struct task_group *tg) { } |
| |
| int alloc_fair_sched_group(struct task_group *tg, struct task_group *parent) |
| { |
| return 1; |
| } |
| |
| void online_fair_sched_group(struct task_group *tg) { } |
| |
| void unregister_fair_sched_group(struct task_group *tg) { } |
| |
| #endif /* CONFIG_FAIR_GROUP_SCHED */ |
| |
| |
| static unsigned int get_rr_interval_fair(struct rq *rq, struct task_struct *task) |
| { |
| struct sched_entity *se = &task->se; |
| unsigned int rr_interval = 0; |
| |
| /* |
| * Time slice is 0 for SCHED_OTHER tasks that are on an otherwise |
| * idle runqueue: |
| */ |
| if (rq->cfs.load.weight) |
| rr_interval = NS_TO_JIFFIES(sched_slice(cfs_rq_of(se), se)); |
| |
| return rr_interval; |
| } |
| |
| /* |
| * All the scheduling class methods: |
| */ |
| const struct sched_class fair_sched_class = { |
| .next = &idle_sched_class, |
| .enqueue_task = enqueue_task_fair, |
| .dequeue_task = dequeue_task_fair, |
| .yield_task = yield_task_fair, |
| .yield_to_task = yield_to_task_fair, |
| |
| .check_preempt_curr = check_preempt_wakeup, |
| |
| .pick_next_task = pick_next_task_fair, |
| .put_prev_task = put_prev_task_fair, |
| |
| #ifdef CONFIG_SMP |
| .select_task_rq = select_task_rq_fair, |
| .migrate_task_rq = migrate_task_rq_fair, |
| |
| .rq_online = rq_online_fair, |
| .rq_offline = rq_offline_fair, |
| |
| .task_dead = task_dead_fair, |
| .set_cpus_allowed = set_cpus_allowed_common, |
| #endif |
| |
| .set_curr_task = set_curr_task_fair, |
| .task_tick = task_tick_fair, |
| .task_fork = task_fork_fair, |
| |
| .prio_changed = prio_changed_fair, |
| .switched_from = switched_from_fair, |
| .switched_to = switched_to_fair, |
| |
| .get_rr_interval = get_rr_interval_fair, |
| |
| .update_curr = update_curr_fair, |
| |
| #ifdef CONFIG_FAIR_GROUP_SCHED |
| .task_change_group = task_change_group_fair, |
| #endif |
| #ifdef CONFIG_SCHED_HMP |
| .fixup_hmp_sched_stats = fixup_hmp_sched_stats_fair, |
| #endif |
| }; |
| |
| #ifdef CONFIG_SCHED_DEBUG |
| void print_cfs_stats(struct seq_file *m, int cpu) |
| { |
| struct cfs_rq *cfs_rq; |
| |
| rcu_read_lock(); |
| for_each_leaf_cfs_rq(cpu_rq(cpu), cfs_rq) |
| print_cfs_rq(m, cpu, cfs_rq); |
| rcu_read_unlock(); |
| } |
| |
| #ifdef CONFIG_NUMA_BALANCING |
| void show_numa_stats(struct task_struct *p, struct seq_file *m) |
| { |
| int node; |
| unsigned long tsf = 0, tpf = 0, gsf = 0, gpf = 0; |
| |
| for_each_online_node(node) { |
| if (p->numa_faults) { |
| tsf = p->numa_faults[task_faults_idx(NUMA_MEM, node, 0)]; |
| tpf = p->numa_faults[task_faults_idx(NUMA_MEM, node, 1)]; |
| } |
| if (p->numa_group) { |
| gsf = p->numa_group->faults[task_faults_idx(NUMA_MEM, node, 0)], |
| gpf = p->numa_group->faults[task_faults_idx(NUMA_MEM, node, 1)]; |
| } |
| print_numa_stats(m, node, tsf, tpf, gsf, gpf); |
| } |
| } |
| #endif /* CONFIG_NUMA_BALANCING */ |
| #endif /* CONFIG_SCHED_DEBUG */ |
| |
| __init void init_sched_fair_class(void) |
| { |
| #ifdef CONFIG_SMP |
| open_softirq(SCHED_SOFTIRQ, run_rebalance_domains); |
| |
| #ifdef CONFIG_NO_HZ_COMMON |
| nohz.next_balance = jiffies; |
| zalloc_cpumask_var(&nohz.idle_cpus_mask, GFP_NOWAIT); |
| #endif |
| #endif /* SMP */ |
| |
| } |
| |
| /* QHMP/Zone sched implementation begins here */ |
| |
| #ifdef CONFIG_SCHED_HMP |
| #ifdef CONFIG_SMP |
| |
| /* CPU selection flag */ |
| #define SBC_FLAG_PREV_CPU 0x1 |
| #define SBC_FLAG_BEST_CAP_CPU 0x2 |
| #define SBC_FLAG_CPU_COST 0x4 |
| #define SBC_FLAG_MIN_COST 0x8 |
| #define SBC_FLAG_IDLE_LEAST_LOADED 0x10 |
| #define SBC_FLAG_IDLE_CSTATE 0x20 |
| #define SBC_FLAG_COST_CSTATE_TIE_BREAKER 0x40 |
| #define SBC_FLAG_COST_CSTATE_PREV_CPU_TIE_BREAKER 0x80 |
| #define SBC_FLAG_CSTATE_LOAD 0x100 |
| #define SBC_FLAG_BEST_SIBLING 0x200 |
| #define SBC_FLAG_WAKER_CPU 0x400 |
| #define SBC_FLAG_PACK_TASK 0x800 |
| |
| /* Cluster selection flag */ |
| #define SBC_FLAG_COLOC_CLUSTER 0x10000 |
| #define SBC_FLAG_WAKER_CLUSTER 0x20000 |
| #define SBC_FLAG_BACKUP_CLUSTER 0x40000 |
| #define SBC_FLAG_BOOST_CLUSTER 0x80000 |
| |
| struct cpu_select_env { |
| struct task_struct *p; |
| struct related_thread_group *rtg; |
| u8 reason; |
| u8 need_idle:1; |
| u8 need_waker_cluster:1; |
| u8 sync:1; |
| enum sched_boost_policy boost_policy; |
| u8 pack_task:1; |
| int prev_cpu; |
| DECLARE_BITMAP(candidate_list, NR_CPUS); |
| DECLARE_BITMAP(backup_list, NR_CPUS); |
| u64 task_load; |
| u64 cpu_load; |
| u32 sbc_best_flag; |
| u32 sbc_best_cluster_flag; |
| struct cpumask search_cpus; |
| }; |
| |
| struct cluster_cpu_stats { |
| int best_idle_cpu, least_loaded_cpu; |
| int best_capacity_cpu, best_cpu, best_sibling_cpu; |
| int min_cost, best_sibling_cpu_cost; |
| int best_cpu_wakeup_latency; |
| u64 min_load, best_load, best_sibling_cpu_load; |
| s64 highest_spare_capacity; |
| }; |
| |
| /* |
| * Should task be woken to any available idle cpu? |
| * |
| * Waking tasks to idle cpu has mixed implications on both performance and |
| * power. In many cases, scheduler can't estimate correctly impact of using idle |
| * cpus on either performance or power. PF_WAKE_UP_IDLE allows external kernel |
| * module to pass a strong hint to scheduler that the task in question should be |
| * woken to idle cpu, generally to improve performance. |
| */ |
| static inline int wake_to_idle(struct task_struct *p) |
| { |
| return (current->flags & PF_WAKE_UP_IDLE) || |
| (p->flags & PF_WAKE_UP_IDLE); |
| } |
| |
| static int spill_threshold_crossed(struct cpu_select_env *env, struct rq *rq) |
| { |
| u64 total_load; |
| |
| total_load = env->task_load + env->cpu_load; |
| |
| if (total_load > sched_spill_load || |
| (rq->nr_running + 1) > sysctl_sched_spill_nr_run) |
| return 1; |
| |
| return 0; |
| } |
| |
| static int skip_cpu(int cpu, struct cpu_select_env *env) |
| { |
| int tcpu = task_cpu(env->p); |
| int skip = 0; |
| |
| if (!env->reason) |
| return 0; |
| |
| if (is_reserved(cpu)) |
| return 1; |
| |
| switch (env->reason) { |
| case UP_MIGRATION: |
| skip = !idle_cpu(cpu); |
| break; |
| case IRQLOAD_MIGRATION: |
| /* Purposely fall through */ |
| default: |
| skip = (cpu == tcpu); |
| break; |
| } |
| |
| return skip; |
| } |
| |
| static inline int |
| acceptable_capacity(struct sched_cluster *cluster, struct cpu_select_env *env) |
| { |
| int tcpu; |
| |
| if (!env->reason) |
| return 1; |
| |
| tcpu = task_cpu(env->p); |
| switch (env->reason) { |
| case UP_MIGRATION: |
| return cluster->capacity > cpu_capacity(tcpu); |
| |
| case DOWN_MIGRATION: |
| return cluster->capacity < cpu_capacity(tcpu); |
| |
| default: |
| break; |
| } |
| |
| return 1; |
| } |
| |
| static int |
| skip_cluster(struct sched_cluster *cluster, struct cpu_select_env *env) |
| { |
| if (!test_bit(cluster->id, env->candidate_list)) |
| return 1; |
| |
| if (!acceptable_capacity(cluster, env)) { |
| __clear_bit(cluster->id, env->candidate_list); |
| return 1; |
| } |
| |
| return 0; |
| } |
| |
| static struct sched_cluster * |
| select_least_power_cluster(struct cpu_select_env *env) |
| { |
| struct sched_cluster *cluster; |
| |
| if (env->rtg) { |
| int cpu = cluster_first_cpu(env->rtg->preferred_cluster); |
| |
| env->task_load = scale_load_to_cpu(task_load(env->p), cpu); |
| |
| if (task_load_will_fit(env->p, env->task_load, |
| cpu, env->boost_policy)) { |
| env->sbc_best_cluster_flag |= SBC_FLAG_COLOC_CLUSTER; |
| |
| if (env->boost_policy == SCHED_BOOST_NONE) |
| return env->rtg->preferred_cluster; |
| |
| for_each_sched_cluster(cluster) { |
| if (cluster != env->rtg->preferred_cluster) { |
| __set_bit(cluster->id, |
| env->backup_list); |
| __clear_bit(cluster->id, |
| env->candidate_list); |
| } |
| } |
| |
| return env->rtg->preferred_cluster; |
| } |
| |
| /* |
| * Since the task load does not fit on the preferred |
| * cluster anymore, pretend that the task does not |
| * have any preferred cluster. This allows the waking |
| * task to get the appropriate CPU it needs as per the |
| * non co-location placement policy without having to |
| * wait until the preferred cluster is updated. |
| */ |
| env->rtg = NULL; |
| } |
| |
| for_each_sched_cluster(cluster) { |
| if (!skip_cluster(cluster, env)) { |
| int cpu = cluster_first_cpu(cluster); |
| |
| env->task_load = scale_load_to_cpu(task_load(env->p), |
| cpu); |
| if (task_load_will_fit(env->p, env->task_load, cpu, |
| env->boost_policy)) |
| return cluster; |
| |
| __set_bit(cluster->id, env->backup_list); |
| __clear_bit(cluster->id, env->candidate_list); |
| } |
| } |
| |
| return NULL; |
| } |
| |
| static struct sched_cluster * |
| next_candidate(const unsigned long *list, int start, int end) |
| { |
| int cluster_id; |
| |
| cluster_id = find_next_bit(list, end, start - 1 + 1); |
| if (cluster_id >= end) |
| return NULL; |
| |
| return sched_cluster[cluster_id]; |
| } |
| |
| static void |
| update_spare_capacity(struct cluster_cpu_stats *stats, |
| struct cpu_select_env *env, int cpu, int capacity, |
| u64 cpu_load) |
| { |
| s64 spare_capacity = sched_ravg_window - cpu_load; |
| |
| if (spare_capacity > 0 && |
| (spare_capacity > stats->highest_spare_capacity || |
| (spare_capacity == stats->highest_spare_capacity && |
| ((!env->need_waker_cluster && |
| capacity > cpu_capacity(stats->best_capacity_cpu)) || |
| (env->need_waker_cluster && |
| cpu_rq(cpu)->nr_running < |
| cpu_rq(stats->best_capacity_cpu)->nr_running))))) { |
| /* |
| * If sync waker is the only runnable of CPU, cr_avg of the |
| * CPU is 0 so we have high chance to place the wakee on the |
| * waker's CPU which likely causes preemtion of the waker. |
| * This can lead migration of preempted waker. Place the |
| * wakee on the real idle CPU when it's possible by checking |
| * nr_running to avoid such preemption. |
| */ |
| stats->highest_spare_capacity = spare_capacity; |
| stats->best_capacity_cpu = cpu; |
| } |
| } |
| |
| static inline void find_backup_cluster( |
| struct cpu_select_env *env, struct cluster_cpu_stats *stats) |
| { |
| struct sched_cluster *next = NULL; |
| int i; |
| struct cpumask search_cpus; |
| |
| while (!bitmap_empty(env->backup_list, num_clusters)) { |
| next = next_candidate(env->backup_list, 0, num_clusters); |
| __clear_bit(next->id, env->backup_list); |
| |
| cpumask_and(&search_cpus, &env->search_cpus, &next->cpus); |
| for_each_cpu(i, &search_cpus) { |
| trace_sched_cpu_load_wakeup(cpu_rq(i), idle_cpu(i), |
| sched_irqload(i), power_cost(i, task_load(env->p) + |
| cpu_cravg_sync(i, env->sync)), 0); |
| |
| update_spare_capacity(stats, env, i, next->capacity, |
| cpu_load_sync(i, env->sync)); |
| } |
| env->sbc_best_cluster_flag = SBC_FLAG_BACKUP_CLUSTER; |
| } |
| } |
| |
| struct sched_cluster * |
| next_best_cluster(struct sched_cluster *cluster, struct cpu_select_env *env, |
| struct cluster_cpu_stats *stats) |
| { |
| struct sched_cluster *next = NULL; |
| |
| __clear_bit(cluster->id, env->candidate_list); |
| |
| if (env->rtg && preferred_cluster(cluster, env->p)) |
| return NULL; |
| |
| do { |
| if (bitmap_empty(env->candidate_list, num_clusters)) |
| return NULL; |
| |
| next = next_candidate(env->candidate_list, 0, num_clusters); |
| if (next) { |
| if (next->min_power_cost > stats->min_cost) { |
| clear_bit(next->id, env->candidate_list); |
| next = NULL; |
| continue; |
| } |
| |
| if (skip_cluster(next, env)) |
| next = NULL; |
| } |
| } while (!next); |
| |
| env->task_load = scale_load_to_cpu(task_load(env->p), |
| cluster_first_cpu(next)); |
| return next; |
| } |
| |
| #ifdef CONFIG_SCHED_HMP_CSTATE_AWARE |
| static void __update_cluster_stats(int cpu, struct cluster_cpu_stats *stats, |
| struct cpu_select_env *env, int cpu_cost) |
| { |
| int wakeup_latency; |
| int prev_cpu = env->prev_cpu; |
| |
| wakeup_latency = cpu_rq(cpu)->wakeup_latency; |
| |
| if (env->need_idle) { |
| stats->min_cost = cpu_cost; |
| if (idle_cpu(cpu)) { |
| if (wakeup_latency < stats->best_cpu_wakeup_latency || |
| (wakeup_latency == stats->best_cpu_wakeup_latency && |
| cpu == prev_cpu)) { |
| stats->best_idle_cpu = cpu; |
| stats->best_cpu_wakeup_latency = wakeup_latency; |
| } |
| } else { |
| if (env->cpu_load < stats->min_load || |
| (env->cpu_load == stats->min_load && |
| cpu == prev_cpu)) { |
| stats->least_loaded_cpu = cpu; |
| stats->min_load = env->cpu_load; |
| } |
| } |
| |
| return; |
| } |
| |
| if (cpu_cost < stats->min_cost) { |
| stats->min_cost = cpu_cost; |
| stats->best_cpu_wakeup_latency = wakeup_latency; |
| stats->best_load = env->cpu_load; |
| stats->best_cpu = cpu; |
| env->sbc_best_flag = SBC_FLAG_CPU_COST; |
| return; |
| } |
| |
| /* CPU cost is the same. Start breaking the tie by C-state */ |
| |
| if (wakeup_latency > stats->best_cpu_wakeup_latency) |
| return; |
| |
| if (wakeup_latency < stats->best_cpu_wakeup_latency) { |
| stats->best_cpu_wakeup_latency = wakeup_latency; |
| stats->best_load = env->cpu_load; |
| stats->best_cpu = cpu; |
| env->sbc_best_flag = SBC_FLAG_COST_CSTATE_TIE_BREAKER; |
| return; |
| } |
| |
| /* C-state is the same. Use prev CPU to break the tie */ |
| if (cpu == prev_cpu) { |
| stats->best_cpu = cpu; |
| env->sbc_best_flag = SBC_FLAG_COST_CSTATE_PREV_CPU_TIE_BREAKER; |
| return; |
| } |
| |
| if (stats->best_cpu != prev_cpu && |
| ((wakeup_latency == 0 && env->cpu_load < stats->best_load) || |
| (wakeup_latency > 0 && env->cpu_load > stats->best_load))) { |
| stats->best_load = env->cpu_load; |
| stats->best_cpu = cpu; |
| env->sbc_best_flag = SBC_FLAG_CSTATE_LOAD; |
| } |
| } |
| #else /* CONFIG_SCHED_HMP_CSTATE_AWARE */ |
| static void __update_cluster_stats(int cpu, struct cluster_cpu_stats *stats, |
| struct cpu_select_env *env, int cpu_cost) |
| { |
| int prev_cpu = env->prev_cpu; |
| |
| if (cpu != prev_cpu && cpus_share_cache(prev_cpu, cpu)) { |
| if (stats->best_sibling_cpu_cost > cpu_cost || |
| (stats->best_sibling_cpu_cost == cpu_cost && |
| stats->best_sibling_cpu_load > env->cpu_load)) { |
| stats->best_sibling_cpu_cost = cpu_cost; |
| stats->best_sibling_cpu_load = env->cpu_load; |
| stats->best_sibling_cpu = cpu; |
| } |
| } |
| |
| if ((cpu_cost < stats->min_cost) || |
| ((stats->best_cpu != prev_cpu && |
| stats->min_load > env->cpu_load) || cpu == prev_cpu)) { |
| if (env->need_idle) { |
| if (idle_cpu(cpu)) { |
| stats->min_cost = cpu_cost; |
| stats->best_idle_cpu = cpu; |
| } |
| } else { |
| stats->min_cost = cpu_cost; |
| stats->min_load = env->cpu_load; |
| stats->best_cpu = cpu; |
| env->sbc_best_flag = SBC_FLAG_MIN_COST; |
| } |
| } |
| } |
| #endif /* CONFIG_SCHED_HMP_CSTATE_AWARE */ |
| |
| static void update_cluster_stats(int cpu, struct cluster_cpu_stats *stats, |
| struct cpu_select_env *env) |
| { |
| int cpu_cost; |
| |
| /* |
| * We try to find the least loaded *busy* CPU irrespective |
| * of the power cost. |
| */ |
| if (env->pack_task) |
| cpu_cost = cpu_min_power_cost(cpu); |
| |
| else |
| cpu_cost = power_cost(cpu, task_load(env->p) + |
| cpu_cravg_sync(cpu, env->sync)); |
| |
| if (cpu_cost <= stats->min_cost) |
| __update_cluster_stats(cpu, stats, env, cpu_cost); |
| } |
| |
| static void find_best_cpu_in_cluster(struct sched_cluster *c, |
| struct cpu_select_env *env, struct cluster_cpu_stats *stats) |
| { |
| int i; |
| struct cpumask search_cpus; |
| |
| cpumask_and(&search_cpus, &env->search_cpus, &c->cpus); |
| |
| env->need_idle = wake_to_idle(env->p) || c->wake_up_idle; |
| |
| for_each_cpu(i, &search_cpus) { |
| env->cpu_load = cpu_load_sync(i, env->sync); |
| |
| trace_sched_cpu_load_wakeup(cpu_rq(i), idle_cpu(i), |
| sched_irqload(i), |
| power_cost(i, task_load(env->p) + |
| cpu_cravg_sync(i, env->sync)), 0); |
| |
| if (skip_cpu(i, env)) |
| continue; |
| |
| update_spare_capacity(stats, env, i, c->capacity, |
| env->cpu_load); |
| |
| /* |
| * need_idle takes precedence over sched boost but when both |
| * are set, idlest CPU with in all the clusters is selected |
| * when boost_policy = BOOST_ON_ALL whereas idlest CPU in the |
| * big cluster is selected within boost_policy = BOOST_ON_BIG. |
| */ |
| if ((!env->need_idle && |
| env->boost_policy != SCHED_BOOST_NONE) || |
| env->need_waker_cluster || |
| sched_cpu_high_irqload(i) || |
| spill_threshold_crossed(env, cpu_rq(i))) |
| continue; |
| |
| update_cluster_stats(i, stats, env); |
| } |
| } |
| |
| static inline void init_cluster_cpu_stats(struct cluster_cpu_stats *stats) |
| { |
| stats->best_cpu = stats->best_idle_cpu = -1; |
| stats->best_capacity_cpu = stats->best_sibling_cpu = -1; |
| stats->min_cost = stats->best_sibling_cpu_cost = INT_MAX; |
| stats->min_load = stats->best_sibling_cpu_load = ULLONG_MAX; |
| stats->highest_spare_capacity = 0; |
| stats->least_loaded_cpu = -1; |
| stats->best_cpu_wakeup_latency = INT_MAX; |
| /* No need to initialize stats->best_load */ |
| } |
| |
| static inline bool env_has_special_flags(struct cpu_select_env *env) |
| { |
| if (env->need_idle || env->boost_policy != SCHED_BOOST_NONE || |
| env->reason) |
| return true; |
| |
| return false; |
| } |
| |
| static inline bool |
| bias_to_prev_cpu(struct cpu_select_env *env, struct cluster_cpu_stats *stats) |
| { |
| int prev_cpu; |
| struct task_struct *task = env->p; |
| struct sched_cluster *cluster; |
| |
| if (!task->ravg.mark_start || !sched_short_sleep_task_threshold) |
| return false; |
| |
| prev_cpu = env->prev_cpu; |
| if (!cpumask_test_cpu(prev_cpu, &env->search_cpus)) |
| return false; |
| |
| if (task->ravg.mark_start - task->last_cpu_selected_ts >= |
| sched_long_cpu_selection_threshold) |
| return false; |
| |
| /* |
| * This function should be used by task wake up path only as it's |
| * assuming p->last_switch_out_ts as last sleep time. |
| * p->last_switch_out_ts can denote last preemption time as well as |
| * last sleep time. |
| */ |
| if (task->ravg.mark_start - task->last_switch_out_ts >= |
| sched_short_sleep_task_threshold) |
| return false; |
| |
| env->task_load = scale_load_to_cpu(task_load(task), prev_cpu); |
| cluster = cpu_rq(prev_cpu)->cluster; |
| |
| if (!task_load_will_fit(task, env->task_load, prev_cpu, |
| sched_boost_policy())) { |
| |
| __set_bit(cluster->id, env->backup_list); |
| __clear_bit(cluster->id, env->candidate_list); |
| return false; |
| } |
| |
| env->cpu_load = cpu_load_sync(prev_cpu, env->sync); |
| if (sched_cpu_high_irqload(prev_cpu) || |
| spill_threshold_crossed(env, cpu_rq(prev_cpu))) { |
| update_spare_capacity(stats, env, prev_cpu, |
| cluster->capacity, env->cpu_load); |
| cpumask_clear_cpu(prev_cpu, &env->search_cpus); |
| return false; |
| } |
| |
| return true; |
| } |
| |
| static inline bool |
| wake_to_waker_cluster(struct cpu_select_env *env) |
| { |
| return env->sync && |
| task_load(current) > sched_big_waker_task_load && |
| task_load(env->p) < sched_small_wakee_task_load; |
| } |
| |
| static inline bool |
| bias_to_waker_cpu(struct cpu_select_env *env, int cpu) |
| { |
| return sysctl_sched_prefer_sync_wakee_to_waker && |
| cpu_rq(cpu)->nr_running == 1 && |
| cpumask_test_cpu(cpu, &env->search_cpus); |
| } |
| |
| static inline int |
| cluster_allowed(struct cpu_select_env *env, struct sched_cluster *cluster) |
| { |
| return cpumask_intersects(&env->search_cpus, &cluster->cpus); |
| } |
| |
| /* return cheapest cpu that can fit this task */ |
| static int select_best_cpu(struct task_struct *p, int target, int reason, |
| int sync) |
| { |
| struct sched_cluster *cluster, *pref_cluster = NULL; |
| struct cluster_cpu_stats stats; |
| struct related_thread_group *grp; |
| unsigned int sbc_flag = 0; |
| int cpu = raw_smp_processor_id(); |
| bool special; |
| |
| struct cpu_select_env env = { |
| .p = p, |
| .reason = reason, |
| .need_idle = wake_to_idle(p), |
| .need_waker_cluster = 0, |
| .sync = sync, |
| .prev_cpu = target, |
| .rtg = NULL, |
| .sbc_best_flag = 0, |
| .sbc_best_cluster_flag = 0, |
| .pack_task = false, |
| }; |
| |
| env.boost_policy = task_sched_boost(p) ? |
| sched_boost_policy() : SCHED_BOOST_NONE; |
| |
| bitmap_copy(env.candidate_list, all_cluster_ids, NR_CPUS); |
| bitmap_zero(env.backup_list, NR_CPUS); |
| |
| cpumask_and(&env.search_cpus, tsk_cpus_allowed(p), cpu_active_mask); |
| cpumask_andnot(&env.search_cpus, &env.search_cpus, cpu_isolated_mask); |
| |
| init_cluster_cpu_stats(&stats); |
| special = env_has_special_flags(&env); |
| |
| rcu_read_lock(); |
| |
| grp = task_related_thread_group(p); |
| |
| if (grp && grp->preferred_cluster) { |
| pref_cluster = grp->preferred_cluster; |
| if (!cluster_allowed(&env, pref_cluster)) |
| clear_bit(pref_cluster->id, env.candidate_list); |
| else |
| env.rtg = grp; |
| } else if (!special) { |
| cluster = cpu_rq(cpu)->cluster; |
| if (wake_to_waker_cluster(&env)) { |
| if (bias_to_waker_cpu(&env, cpu)) { |
| target = cpu; |
| sbc_flag = SBC_FLAG_WAKER_CLUSTER | |
| SBC_FLAG_WAKER_CPU; |
| goto out; |
| } else if (cluster_allowed(&env, cluster)) { |
| env.need_waker_cluster = 1; |
| bitmap_zero(env.candidate_list, NR_CPUS); |
| __set_bit(cluster->id, env.candidate_list); |
| env.sbc_best_cluster_flag = |
| SBC_FLAG_WAKER_CLUSTER; |
| } |
| } else if (bias_to_prev_cpu(&env, &stats)) { |
| sbc_flag = SBC_FLAG_PREV_CPU; |
| goto out; |
| } |
| } |
| |
| if (!special && is_short_burst_task(p)) { |
| env.pack_task = true; |
| sbc_flag = SBC_FLAG_PACK_TASK; |
| } |
| retry: |
| cluster = select_least_power_cluster(&env); |
| |
| if (!cluster) |
| goto out; |
| |
| /* |
| * 'cluster' now points to the minimum power cluster which can satisfy |
| * task's perf goals. Walk down the cluster list starting with that |
| * cluster. For non-small tasks, skip clusters that don't have |
| * mostly_idle/idle cpus |
| */ |
| |
| do { |
| find_best_cpu_in_cluster(cluster, &env, &stats); |
| |
| } while ((cluster = next_best_cluster(cluster, &env, &stats))); |
| |
| if (env.need_idle) { |
| if (stats.best_idle_cpu >= 0) { |
| target = stats.best_idle_cpu; |
| sbc_flag |= SBC_FLAG_IDLE_CSTATE; |
| } else if (stats.least_loaded_cpu >= 0) { |
| target = stats.least_loaded_cpu; |
| sbc_flag |= SBC_FLAG_IDLE_LEAST_LOADED; |
| } |
| } else if (stats.best_cpu >= 0) { |
| if (stats.best_cpu != task_cpu(p) && |
| stats.min_cost == stats.best_sibling_cpu_cost) { |
| stats.best_cpu = stats.best_sibling_cpu; |
| sbc_flag |= SBC_FLAG_BEST_SIBLING; |
| } |
| sbc_flag |= env.sbc_best_flag; |
| target = stats.best_cpu; |
| } else { |
| if (env.rtg && env.boost_policy == SCHED_BOOST_NONE) { |
| env.rtg = NULL; |
| goto retry; |
| } |
| |
| /* |
| * With boost_policy == SCHED_BOOST_ON_BIG, we reach here with |
| * backup_list = little cluster, candidate_list = none and |
| * stats->best_capacity_cpu points the best spare capacity |
| * CPU among the CPUs in the big cluster. |
| */ |
| if (env.boost_policy == SCHED_BOOST_ON_BIG && |
| stats.best_capacity_cpu >= 0) |
| sbc_flag |= SBC_FLAG_BOOST_CLUSTER; |
| else |
| find_backup_cluster(&env, &stats); |
| |
| if (stats.best_capacity_cpu >= 0) { |
| target = stats.best_capacity_cpu; |
| sbc_flag |= SBC_FLAG_BEST_CAP_CPU; |
| } |
| } |
| p->last_cpu_selected_ts = sched_ktime_clock(); |
| out: |
| sbc_flag |= env.sbc_best_cluster_flag; |
| rcu_read_unlock(); |
| trace_sched_task_load(p, sched_boost_policy() && task_sched_boost(p), |
| env.reason, env.sync, env.need_idle, sbc_flag, target); |
| return target; |
| } |
| |
| #ifdef CONFIG_CFS_BANDWIDTH |
| |
| static inline struct task_group *next_task_group(struct task_group *tg) |
| { |
| tg = list_entry_rcu(tg->list.next, typeof(struct task_group), list); |
| |
| return (&tg->list == &task_groups) ? NULL : tg; |
| } |
| |
| /* Iterate over all cfs_rq in a cpu */ |
| #define for_each_cfs_rq(cfs_rq, tg, cpu) \ |
| for (tg = container_of(&task_groups, struct task_group, list); \ |
| ((tg = next_task_group(tg)) && (cfs_rq = tg->cfs_rq[cpu]));) |
| |
| void reset_cfs_rq_hmp_stats(int cpu, int reset_cra) |
| { |
| struct task_group *tg; |
| struct cfs_rq *cfs_rq; |
| |
| rcu_read_lock(); |
| |
| for_each_cfs_rq(cfs_rq, tg, cpu) |
| reset_hmp_stats(&cfs_rq->hmp_stats, reset_cra); |
| |
| rcu_read_unlock(); |
| } |
| |
| static inline int cfs_rq_throttled(struct cfs_rq *cfs_rq); |
| |
| static void inc_cfs_rq_hmp_stats(struct cfs_rq *cfs_rq, |
| struct task_struct *p, int change_cra); |
| static void dec_cfs_rq_hmp_stats(struct cfs_rq *cfs_rq, |
| struct task_struct *p, int change_cra); |
| |
| /* Add task's contribution to a cpu' HMP statistics */ |
| void inc_hmp_sched_stats_fair(struct rq *rq, |
| struct task_struct *p, int change_cra) |
| { |
| struct cfs_rq *cfs_rq; |
| struct sched_entity *se = &p->se; |
| |
| /* |
| * Although below check is not strictly required (as |
| * inc/dec_nr_big_task and inc/dec_cumulative_runnable_avg called |
| * from inc_cfs_rq_hmp_stats() have similar checks), we gain a bit on |
| * efficiency by short-circuiting for_each_sched_entity() loop when |
| * sched_disable_window_stats |
| */ |
| if (sched_disable_window_stats) |
| return; |
| |
| for_each_sched_entity(se) { |
| cfs_rq = cfs_rq_of(se); |
| inc_cfs_rq_hmp_stats(cfs_rq, p, change_cra); |
| if (cfs_rq_throttled(cfs_rq)) |
| break; |
| } |
| |
| /* Update rq->hmp_stats only if we didn't find any throttled cfs_rq */ |
| if (!se) |
| inc_rq_hmp_stats(rq, p, change_cra); |
| } |
| |
| static void fixup_hmp_sched_stats_fair(struct rq *rq, struct task_struct *p, |
| u32 new_task_load, u32 new_pred_demand) |
| { |
| struct cfs_rq *cfs_rq; |
| struct sched_entity *se = &p->se; |
| s64 task_load_delta = (s64)new_task_load - task_load(p); |
| s64 pred_demand_delta = PRED_DEMAND_DELTA; |
| |
| for_each_sched_entity(se) { |
| cfs_rq = cfs_rq_of(se); |
| |
| fixup_cumulative_runnable_avg(&cfs_rq->hmp_stats, p, |
| task_load_delta, |
| pred_demand_delta); |
| fixup_nr_big_tasks(&cfs_rq->hmp_stats, p, task_load_delta); |
| if (cfs_rq_throttled(cfs_rq)) |
| break; |
| } |
| |
| /* Fix up rq->hmp_stats only if we didn't find any throttled cfs_rq */ |
| if (!se) { |
| fixup_cumulative_runnable_avg(&rq->hmp_stats, p, |
| task_load_delta, |
| pred_demand_delta); |
| fixup_nr_big_tasks(&rq->hmp_stats, p, task_load_delta); |
| } |
| } |
| |
| static int task_will_be_throttled(struct task_struct *p); |
| |
| #else /* CONFIG_CFS_BANDWIDTH */ |
| |
| inline void reset_cfs_rq_hmp_stats(int cpu, int reset_cra) { } |
| |
| static void |
| fixup_hmp_sched_stats_fair(struct rq *rq, struct task_struct *p, |
| u32 new_task_load, u32 new_pred_demand) |
| { |
| s64 task_load_delta = (s64)new_task_load - task_load(p); |
| s64 pred_demand_delta = PRED_DEMAND_DELTA; |
| |
| fixup_cumulative_runnable_avg(&rq->hmp_stats, p, task_load_delta, |
| pred_demand_delta); |
| fixup_nr_big_tasks(&rq->hmp_stats, p, task_load_delta); |
| } |
| |
| static inline int task_will_be_throttled(struct task_struct *p) |
| { |
| return 0; |
| } |
| |
| void inc_hmp_sched_stats_fair(struct rq *rq, |
| struct task_struct *p, int change_cra) |
| { |
| inc_nr_big_task(&rq->hmp_stats, p); |
| } |
| |
| #endif /* CONFIG_CFS_BANDWIDTH */ |
| |
| /* |
| * Reset balance_interval at all sched_domain levels of given cpu, so that it |
| * honors kick. |
| */ |
| static inline void reset_balance_interval(int cpu) |
| { |
| struct sched_domain *sd; |
| |
| if (cpu >= nr_cpu_ids) |
| return; |
| |
| rcu_read_lock(); |
| for_each_domain(cpu, sd) |
| sd->balance_interval = 0; |
| rcu_read_unlock(); |
| } |
| |
| /* |
| * Check if a task is on the "wrong" cpu (i.e its current cpu is not the ideal |
| * cpu as per its demand or priority) |
| * |
| * Returns reason why task needs to be migrated |
| */ |
| static inline int migration_needed(struct task_struct *p, int cpu) |
| { |
| int nice; |
| struct related_thread_group *grp; |
| |
| if (p->state != TASK_RUNNING || p->nr_cpus_allowed == 1) |
| return 0; |
| |
| /* No need to migrate task that is about to be throttled */ |
| if (task_will_be_throttled(p)) |
| return 0; |
| |
| if (sched_boost_policy() == SCHED_BOOST_ON_BIG && |
| cpu_capacity(cpu) != max_capacity && task_sched_boost(p)) |
| return UP_MIGRATION; |
| |
| if (sched_cpu_high_irqload(cpu)) |
| return IRQLOAD_MIGRATION; |
| |
| nice = task_nice(p); |
| rcu_read_lock(); |
| grp = task_related_thread_group(p); |
| /* |
| * Don't assume higher capacity means higher power. If the task |
| * is running on the power efficient CPU, avoid migrating it |
| * to a lower capacity cluster. |
| */ |
| if (!grp && (nice > SCHED_UPMIGRATE_MIN_NICE || |
| upmigrate_discouraged(p)) && |
| cpu_capacity(cpu) > min_capacity && |
| cpu_max_power_cost(cpu) == max_power_cost) { |
| rcu_read_unlock(); |
| return DOWN_MIGRATION; |
| } |
| |
| if (!task_will_fit(p, cpu)) { |
| rcu_read_unlock(); |
| return UP_MIGRATION; |
| } |
| rcu_read_unlock(); |
| |
| return 0; |
| } |
| |
| static inline int |
| kick_active_balance(struct rq *rq, struct task_struct *p, int new_cpu) |
| { |
| unsigned long flags; |
| int rc = 0; |
| |
| /* Invoke active balance to force migrate currently running task */ |
| raw_spin_lock_irqsave(&rq->lock, flags); |
| if (!rq->active_balance) { |
| rq->active_balance = 1; |
| rq->push_cpu = new_cpu; |
| get_task_struct(p); |
| rq->push_task = p; |
| rc = 1; |
| } |
| raw_spin_unlock_irqrestore(&rq->lock, flags); |
| |
| return rc; |
| } |
| |
| static DEFINE_RAW_SPINLOCK(migration_lock); |
| |
| /* |
| * Check if currently running task should be migrated to a better cpu. |
| * |
| * Todo: Effect this via changes to nohz_balancer_kick() and load balance? |
| */ |
| void check_for_migration(struct rq *rq, struct task_struct *p) |
| { |
| int cpu = cpu_of(rq), new_cpu; |
| int active_balance = 0, reason; |
| |
| reason = migration_needed(p, cpu); |
| if (!reason) |
| return; |
| |
| raw_spin_lock(&migration_lock); |
| new_cpu = select_best_cpu(p, cpu, reason, 0); |
| |
| if (new_cpu != cpu) { |
| active_balance = kick_active_balance(rq, p, new_cpu); |
| if (active_balance) |
| mark_reserved(new_cpu); |
| } |
| |
| raw_spin_unlock(&migration_lock); |
| |
| if (active_balance) |
| stop_one_cpu_nowait(cpu, active_load_balance_cpu_stop, rq, |
| &rq->active_balance_work); |
| } |
| |
| #ifdef CONFIG_CFS_BANDWIDTH |
| static void init_cfs_rq_hmp_stats(struct cfs_rq *cfs_rq) |
| { |
| cfs_rq->hmp_stats.nr_big_tasks = 0; |
| cfs_rq->hmp_stats.cumulative_runnable_avg = 0; |
| cfs_rq->hmp_stats.pred_demands_sum = 0; |
| } |
| |
| static void inc_cfs_rq_hmp_stats(struct cfs_rq *cfs_rq, |
| struct task_struct *p, int change_cra) |
| { |
| inc_nr_big_task(&cfs_rq->hmp_stats, p); |
| if (change_cra) |
| inc_cumulative_runnable_avg(&cfs_rq->hmp_stats, p); |
| } |
| |
| static void dec_cfs_rq_hmp_stats(struct cfs_rq *cfs_rq, |
| struct task_struct *p, int change_cra) |
| { |
| dec_nr_big_task(&cfs_rq->hmp_stats, p); |
| if (change_cra) |
| dec_cumulative_runnable_avg(&cfs_rq->hmp_stats, p); |
| } |
| |
| static void inc_throttled_cfs_rq_hmp_stats(struct hmp_sched_stats *stats, |
| struct cfs_rq *cfs_rq) |
| { |
| stats->nr_big_tasks += cfs_rq->hmp_stats.nr_big_tasks; |
| stats->cumulative_runnable_avg += |
| cfs_rq->hmp_stats.cumulative_runnable_avg; |
| stats->pred_demands_sum += cfs_rq->hmp_stats.pred_demands_sum; |
| } |
| |
| static void dec_throttled_cfs_rq_hmp_stats(struct hmp_sched_stats *stats, |
| struct cfs_rq *cfs_rq) |
| { |
| stats->nr_big_tasks -= cfs_rq->hmp_stats.nr_big_tasks; |
| stats->cumulative_runnable_avg -= |
| cfs_rq->hmp_stats.cumulative_runnable_avg; |
| stats->pred_demands_sum -= cfs_rq->hmp_stats.pred_demands_sum; |
| |
| BUG_ON(stats->nr_big_tasks < 0 || |
| (s64)stats->cumulative_runnable_avg < 0); |
| BUG_ON((s64)stats->pred_demands_sum < 0); |
| } |
| #endif /* CONFIG_CFS_BANDWIDTH */ |
| |
| static int |
| bail_inter_cluster_balance(struct lb_env *env, struct sd_lb_stats *sds) |
| { |
| int local_cpu, busiest_cpu; |
| int local_capacity, busiest_capacity; |
| int local_pwr_cost, busiest_pwr_cost; |
| int nr_cpus; |
| int boost = sched_boost(); |
| |
| if (!sysctl_sched_restrict_cluster_spill || |
| boost == FULL_THROTTLE_BOOST || boost == CONSERVATIVE_BOOST) |
| return 0; |
| |
| local_cpu = group_first_cpu(sds->local); |
| busiest_cpu = group_first_cpu(sds->busiest); |
| |
| local_capacity = cpu_max_possible_capacity(local_cpu); |
| busiest_capacity = cpu_max_possible_capacity(busiest_cpu); |
| |
| local_pwr_cost = cpu_max_power_cost(local_cpu); |
| busiest_pwr_cost = cpu_max_power_cost(busiest_cpu); |
| |
| if (local_pwr_cost <= busiest_pwr_cost) |
| return 0; |
| |
| if (local_capacity > busiest_capacity && |
| sds->busiest_stat.sum_nr_big_tasks) |
| return 0; |
| |
| nr_cpus = cpumask_weight(sched_group_cpus(sds->busiest)); |
| if ((sds->busiest_stat.group_cpu_load < nr_cpus * sched_spill_load) && |
| (sds->busiest_stat.sum_nr_running < |
| nr_cpus * sysctl_sched_spill_nr_run)) |
| return 1; |
| |
| return 0; |
| } |
| |
| static bool update_sd_pick_busiest_active_balance(struct lb_env *env, |
| struct sd_lb_stats *sds, |
| struct sched_group *sg, |
| struct sg_lb_stats *sgs) |
| { |
| if (env->idle != CPU_NOT_IDLE && |
| cpu_capacity(env->dst_cpu) > group_rq_capacity(sg)) { |
| if (sgs->sum_nr_big_tasks > |
| sds->busiest_stat.sum_nr_big_tasks) { |
| env->flags |= LBF_BIG_TASK_ACTIVE_BALANCE; |
| return true; |
| } |
| } |
| |
| return false; |
| } |
| |
| static struct rq *find_busiest_queue_hmp(struct lb_env *env, |
| struct sched_group *group) |
| { |
| struct rq *busiest = NULL, *busiest_big = NULL; |
| u64 max_runnable_avg = 0, max_runnable_avg_big = 0; |
| int max_nr_big = 0, nr_big; |
| bool find_big = !!(env->flags & LBF_BIG_TASK_ACTIVE_BALANCE); |
| int i; |
| cpumask_t cpus; |
| |
| cpumask_andnot(&cpus, sched_group_cpus(group), cpu_isolated_mask); |
| |
| for_each_cpu(i, &cpus) { |
| struct rq *rq = cpu_rq(i); |
| u64 cumulative_runnable_avg = |
| rq->hmp_stats.cumulative_runnable_avg; |
| |
| if (!cpumask_test_cpu(i, env->cpus)) |
| continue; |
| |
| |
| if (find_big) { |
| nr_big = nr_big_tasks(rq); |
| if (nr_big > max_nr_big || |
| (nr_big > 0 && nr_big == max_nr_big && |
| cumulative_runnable_avg > max_runnable_avg_big)) { |
| max_runnable_avg_big = cumulative_runnable_avg; |
| busiest_big = rq; |
| max_nr_big = nr_big; |
| continue; |
| } |
| } |
| |
| if (cumulative_runnable_avg > max_runnable_avg) { |
| max_runnable_avg = cumulative_runnable_avg; |
| busiest = rq; |
| } |
| } |
| |
| if (busiest_big) |
| return busiest_big; |
| |
| env->flags &= ~LBF_BIG_TASK_ACTIVE_BALANCE; |
| return busiest; |
| } |
| |
| #ifdef CONFIG_NO_HZ_COMMON |
| static inline int find_new_hmp_ilb(int type) |
| { |
| int call_cpu = raw_smp_processor_id(); |
| struct sched_domain *sd; |
| int ilb; |
| |
| rcu_read_lock(); |
| |
| /* Pick an idle cpu "closest" to call_cpu */ |
| for_each_domain(call_cpu, sd) { |
| for_each_cpu_and(ilb, nohz.idle_cpus_mask, |
| sched_domain_span(sd)) { |
| if (idle_cpu(ilb) && (type != NOHZ_KICK_RESTRICT || |
| cpu_max_power_cost(ilb) <= |
| cpu_max_power_cost(call_cpu))) { |
| rcu_read_unlock(); |
| reset_balance_interval(ilb); |
| return ilb; |
| } |
| } |
| } |
| |
| rcu_read_unlock(); |
| return nr_cpu_ids; |
| } |
| |
| static inline int _nohz_kick_needed_hmp(struct rq *rq, int cpu, int *type) |
| { |
| struct sched_domain *sd; |
| int i; |
| |
| if (rq->nr_running < 2) |
| return 0; |
| |
| if (!sysctl_sched_restrict_cluster_spill || |
| sched_boost_policy() == SCHED_BOOST_ON_ALL) |
| return 1; |
| |
| if (cpu_max_power_cost(cpu) == max_power_cost) |
| return 1; |
| |
| rcu_read_lock(); |
| sd = rcu_dereference_check_sched_domain(rq->sd); |
| if (!sd) { |
| rcu_read_unlock(); |
| return 0; |
| } |
| |
| for_each_cpu(i, sched_domain_span(sd)) { |
| if (cpu_load(i) < sched_spill_load && |
| cpu_rq(i)->nr_running < |
| sysctl_sched_spill_nr_run) { |
| /* Change the kick type to limit to CPUs that |
| * are of equal or lower capacity. |
| */ |
| *type = NOHZ_KICK_RESTRICT; |
| break; |
| } |
| } |
| rcu_read_unlock(); |
| return 1; |
| } |
| #endif /* CONFIG_NO_HZ_COMMON */ |
| #endif /* CONFIG_SMP */ |
| |
| #ifdef CONFIG_CFS_BANDWIDTH |
| /* |
| * Check if task is part of a hierarchy where some cfs_rq does not have any |
| * runtime left. |
| * |
| * We can't rely on throttled_hierarchy() to do this test, as |
| * cfs_rq->throttle_count will not be updated yet when this function is called |
| * from scheduler_tick() |
| */ |
| static int task_will_be_throttled(struct task_struct *p) |
| { |
| struct sched_entity *se = &p->se; |
| struct cfs_rq *cfs_rq; |
| |
| if (!cfs_bandwidth_used()) |
| return 0; |
| |
| for_each_sched_entity(se) { |
| cfs_rq = cfs_rq_of(se); |
| if (!cfs_rq->runtime_enabled) |
| continue; |
| if (cfs_rq->runtime_remaining <= 0) |
| return 1; |
| } |
| |
| return 0; |
| } |
| #endif /* CONFIG_CFS_BANDWIDTH */ |
| |
| #endif /* CONFIG_SCHED_HMP */ |