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gerrit-public.fairphone.software / kernel / msm-4.19 / 4e34e719e457f2e031297175410fc0bd4016a085 / . / kernel / sched.c
blob: 9aaf567c5da56d09f877b558afe9a2ccad94b29a [file] [log] [blame]
/*
* kernel/sched.c
*
* Kernel scheduler and related syscalls
*
* Copyright (C) 1991-2002 Linus Torvalds
*
* 1996-12-23 Modified by Dave Grothe to fix bugs in semaphores and
* make semaphores SMP safe
* 1998-11-19 Implemented schedule_timeout() and related stuff
* by Andrea Arcangeli
* 2002-01-04 New ultra-scalable O(1) scheduler by Ingo Molnar:
* hybrid priority-list and round-robin design with
* an array-switch method of distributing timeslices
* and per-CPU runqueues. Cleanups and useful suggestions
* by Davide Libenzi, preemptible kernel bits by Robert Love.
* 2003-09-03 Interactivity tuning by Con Kolivas.
* 2004-04-02 Scheduler domains code by Nick Piggin
* 2007-04-15 Work begun on replacing all interactivity tuning with a
* fair scheduling design by Con Kolivas.
* 2007-05-05 Load balancing (smp-nice) and other improvements
* by Peter Williams
* 2007-05-06 Interactivity improvements to CFS by Mike Galbraith
* 2007-07-01 Group scheduling enhancements by Srivatsa Vaddagiri
* 2007-11-29 RT balancing improvements by Steven Rostedt, Gregory Haskins,
* Thomas Gleixner, Mike Kravetz
*/
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/nmi.h>
#include <linux/init.h>
#include <linux/uaccess.h>
#include <linux/highmem.h>
#include <asm/mmu_context.h>
#include <linux/interrupt.h>
#include <linux/capability.h>
#include <linux/completion.h>
#include <linux/kernel_stat.h>
#include <linux/debug_locks.h>
#include <linux/perf_event.h>
#include <linux/security.h>
#include <linux/notifier.h>
#include <linux/profile.h>
#include <linux/freezer.h>
#include <linux/vmalloc.h>
#include <linux/blkdev.h>
#include <linux/delay.h>
#include <linux/pid_namespace.h>
#include <linux/smp.h>
#include <linux/threads.h>
#include <linux/timer.h>
#include <linux/rcupdate.h>
#include <linux/cpu.h>
#include <linux/cpuset.h>
#include <linux/percpu.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/stop_machine.h>
#include <linux/sysctl.h>
#include <linux/syscalls.h>
#include <linux/times.h>
#include <linux/tsacct_kern.h>
#include <linux/kprobes.h>
#include <linux/delayacct.h>
#include <linux/unistd.h>
#include <linux/pagemap.h>
#include <linux/hrtimer.h>
#include <linux/tick.h>
#include <linux/debugfs.h>
#include <linux/ctype.h>
#include <linux/ftrace.h>
#include <linux/slab.h>
#include <asm/tlb.h>
#include <asm/irq_regs.h>
#include <asm/mutex.h>
#include "sched_cpupri.h"
#include "workqueue_sched.h"
#include "sched_autogroup.h"
#define CREATE_TRACE_POINTS
#include <trace/events/sched.h>
/*
* Convert user-nice values [ -20 ... 0 ... 19 ]
* to static priority [ MAX_RT_PRIO..MAX_PRIO-1 ],
* and back.
*/
#define NICE_TO_PRIO(nice) (MAX_RT_PRIO + (nice) + 20)
#define PRIO_TO_NICE(prio) ((prio) - MAX_RT_PRIO - 20)
#define TASK_NICE(p) PRIO_TO_NICE((p)->static_prio)
/*
* 'User priority' is the nice value converted to something we
* can work with better when scaling various scheduler parameters,
* it's a [ 0 ... 39 ] range.
*/
#define USER_PRIO(p) ((p)-MAX_RT_PRIO)
#define TASK_USER_PRIO(p) USER_PRIO((p)->static_prio)
#define MAX_USER_PRIO (USER_PRIO(MAX_PRIO))
/*
* Helpers for converting nanosecond timing to jiffy resolution
*/
#define NS_TO_JIFFIES(TIME) ((unsigned long)(TIME) / (NSEC_PER_SEC / HZ))
#define NICE_0_LOAD SCHED_LOAD_SCALE
#define NICE_0_SHIFT SCHED_LOAD_SHIFT
/*
* These are the 'tuning knobs' of the scheduler:
*
* default timeslice is 100 msecs (used only for SCHED_RR tasks).
* Timeslices get refilled after they expire.
*/
#define DEF_TIMESLICE (100 * HZ / 1000)
/*
* single value that denotes runtime == period, ie unlimited time.
*/
#define RUNTIME_INF ((u64)~0ULL)
static inline int rt_policy(int policy)
{
if (policy == SCHED_FIFO || policy == SCHED_RR)
return 1;
return 0;
}
static inline int task_has_rt_policy(struct task_struct *p)
{
return rt_policy(p->policy);
}
/*
* This is the priority-queue data structure of the RT scheduling class:
*/
struct rt_prio_array {
DECLARE_BITMAP(bitmap, MAX_RT_PRIO+1); /* include 1 bit for delimiter */
struct list_head queue[MAX_RT_PRIO];
};
struct rt_bandwidth {
/* nests inside the rq lock: */
raw_spinlock_t rt_runtime_lock;
ktime_t rt_period;
u64 rt_runtime;
struct hrtimer rt_period_timer;
};
static struct rt_bandwidth def_rt_bandwidth;
static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun);
static enum hrtimer_restart sched_rt_period_timer(struct hrtimer *timer)
{
struct rt_bandwidth *rt_b =
container_of(timer, struct rt_bandwidth, rt_period_timer);
ktime_t now;
int overrun;
int idle = 0;
for (;;) {
now = hrtimer_cb_get_time(timer);
overrun = hrtimer_forward(timer, now, rt_b->rt_period);
if (!overrun)
break;
idle = do_sched_rt_period_timer(rt_b, overrun);
}
return idle ? HRTIMER_NORESTART : HRTIMER_RESTART;
}
static
void init_rt_bandwidth(struct rt_bandwidth *rt_b, u64 period, u64 runtime)
{
rt_b->rt_period = ns_to_ktime(period);
rt_b->rt_runtime = runtime;
raw_spin_lock_init(&rt_b->rt_runtime_lock);
hrtimer_init(&rt_b->rt_period_timer,
CLOCK_MONOTONIC, HRTIMER_MODE_REL);
rt_b->rt_period_timer.function = sched_rt_period_timer;
}
static inline int rt_bandwidth_enabled(void)
{
return sysctl_sched_rt_runtime >= 0;
}
static void start_rt_bandwidth(struct rt_bandwidth *rt_b)
{
ktime_t now;
if (!rt_bandwidth_enabled() || rt_b->rt_runtime == RUNTIME_INF)
return;
if (hrtimer_active(&rt_b->rt_period_timer))
return;
raw_spin_lock(&rt_b->rt_runtime_lock);
for (;;) {
unsigned long delta;
ktime_t soft, hard;
if (hrtimer_active(&rt_b->rt_period_timer))
break;
now = hrtimer_cb_get_time(&rt_b->rt_period_timer);
hrtimer_forward(&rt_b->rt_period_timer, now, rt_b->rt_period);
soft = hrtimer_get_softexpires(&rt_b->rt_period_timer);
hard = hrtimer_get_expires(&rt_b->rt_period_timer);
delta = ktime_to_ns(ktime_sub(hard, soft));
__hrtimer_start_range_ns(&rt_b->rt_period_timer, soft, delta,
HRTIMER_MODE_ABS_PINNED, 0);
}
raw_spin_unlock(&rt_b->rt_runtime_lock);
}
#ifdef CONFIG_RT_GROUP_SCHED
static void destroy_rt_bandwidth(struct rt_bandwidth *rt_b)
{
hrtimer_cancel(&rt_b->rt_period_timer);
}
#endif
/*
* sched_domains_mutex serializes calls to init_sched_domains,
* detach_destroy_domains and partition_sched_domains.
*/
static DEFINE_MUTEX(sched_domains_mutex);
#ifdef CONFIG_CGROUP_SCHED
#include <linux/cgroup.h>
struct cfs_rq;
static LIST_HEAD(task_groups);
/* task group related information */
struct task_group {
struct cgroup_subsys_state css;
#ifdef CONFIG_FAIR_GROUP_SCHED
/* schedulable entities of this group on each cpu */
struct sched_entity **se;
/* runqueue "owned" by this group on each cpu */
struct cfs_rq **cfs_rq;
unsigned long shares;
atomic_t load_weight;
#endif
#ifdef CONFIG_RT_GROUP_SCHED
struct sched_rt_entity **rt_se;
struct rt_rq **rt_rq;
struct rt_bandwidth rt_bandwidth;
#endif
struct rcu_head rcu;
struct list_head list;
struct task_group *parent;
struct list_head siblings;
struct list_head children;
#ifdef CONFIG_SCHED_AUTOGROUP
struct autogroup *autogroup;
#endif
};
/* task_group_lock serializes the addition/removal of task groups */
static DEFINE_SPINLOCK(task_group_lock);
#ifdef CONFIG_FAIR_GROUP_SCHED
# define ROOT_TASK_GROUP_LOAD NICE_0_LOAD
/*
* A weight of 0 or 1 can cause arithmetics problems.
* A weight of a cfs_rq is the sum of weights of which entities
* are queued on this cfs_rq, so a weight of a entity should not be
* too large, so as the shares value of a task group.
* (The default weight is 1024 - so there's no practical
* limitation from this.)
*/
#define MIN_SHARES (1UL << 1)
#define MAX_SHARES (1UL << 18)
static int root_task_group_load = ROOT_TASK_GROUP_LOAD;
#endif
/* Default task group.
* Every task in system belong to this group at bootup.
*/
struct task_group root_task_group;
#endif /* CONFIG_CGROUP_SCHED */
/* CFS-related fields in a runqueue */
struct cfs_rq {
struct load_weight load;
unsigned long nr_running;
u64 exec_clock;
u64 min_vruntime;
#ifndef CONFIG_64BIT
u64 min_vruntime_copy;
#endif
struct rb_root tasks_timeline;
struct rb_node *rb_leftmost;
struct list_head tasks;
struct list_head *balance_iterator;
/*
* 'curr' points to currently running entity on this cfs_rq.
* It is set to NULL otherwise (i.e when none are currently running).
*/
struct sched_entity *curr, *next, *last, *skip;
#ifdef CONFIG_SCHED_DEBUG
unsigned int nr_spread_over;
#endif
#ifdef CONFIG_FAIR_GROUP_SCHED
struct rq *rq; /* cpu runqueue to which this cfs_rq is attached */
/*
* leaf cfs_rqs are those that hold tasks (lowest schedulable entity in
* a hierarchy). Non-leaf lrqs hold other higher schedulable entities
* (like users, containers etc.)
*
* leaf_cfs_rq_list ties together list of leaf cfs_rq's in a cpu. This
* list is used during load balance.
*/
int on_list;
struct list_head leaf_cfs_rq_list;
struct task_group *tg; /* group that "owns" this runqueue */
#ifdef CONFIG_SMP
/*
* the part of load.weight contributed by tasks
*/
unsigned long task_weight;
/*
* h_load = weight * f(tg)
*
* Where f(tg) is the recursive weight fraction assigned to
* this group.
*/
unsigned long h_load;
/*
* Maintaining per-cpu shares distribution for group scheduling
*
* load_stamp is the last time we updated the load average
* load_last is the last time we updated the load average and saw load
* load_unacc_exec_time is currently unaccounted execution time
*/
u64 load_avg;
u64 load_period;
u64 load_stamp, load_last, load_unacc_exec_time;
unsigned long load_contribution;
#endif
#endif
};
/* Real-Time classes' related field in a runqueue: */
struct rt_rq {
struct rt_prio_array active;
unsigned long rt_nr_running;
#if defined CONFIG_SMP || defined CONFIG_RT_GROUP_SCHED
struct {
int curr; /* highest queued rt task prio */
#ifdef CONFIG_SMP
int next; /* next highest */
#endif
} highest_prio;
#endif
#ifdef CONFIG_SMP
unsigned long rt_nr_migratory;
unsigned long rt_nr_total;
int overloaded;
struct plist_head pushable_tasks;
#endif
int rt_throttled;
u64 rt_time;
u64 rt_runtime;
/* Nests inside the rq lock: */
raw_spinlock_t rt_runtime_lock;
#ifdef CONFIG_RT_GROUP_SCHED
unsigned long rt_nr_boosted;
struct rq *rq;
struct list_head leaf_rt_rq_list;
struct task_group *tg;
#endif
};
#ifdef CONFIG_SMP
/*
* We add the notion of a root-domain which will be used to define per-domain
* variables. Each exclusive cpuset essentially defines an island domain by
* fully partitioning the member cpus from any other cpuset. Whenever a new
* exclusive cpuset is created, we also create and attach a new root-domain
* object.
*
*/
struct root_domain {
atomic_t refcount;
atomic_t rto_count;
struct rcu_head rcu;
cpumask_var_t span;
cpumask_var_t online;
/*
* The "RT overload" flag: it gets set if a CPU has more than
* one runnable RT task.
*/
cpumask_var_t rto_mask;
struct cpupri cpupri;
};
/*
* By default the system creates a single root-domain with all cpus as
* members (mimicking the global state we have today).
*/
static struct root_domain def_root_domain;
#endif /* CONFIG_SMP */
/*
* This is the main, per-CPU runqueue data structure.
*
* Locking rule: those places that want to lock multiple runqueues
* (such as the load balancing or the thread migration code), lock
* acquire operations must be ordered by ascending &runqueue.
*/
struct rq {
/* runqueue lock: */
raw_spinlock_t lock;
/*
* nr_running and cpu_load should be in the same cacheline because
* remote CPUs use both these fields when doing load calculation.
*/
unsigned long nr_running;
#define CPU_LOAD_IDX_MAX 5
unsigned long cpu_load[CPU_LOAD_IDX_MAX];
unsigned long last_load_update_tick;
#ifdef CONFIG_NO_HZ
u64 nohz_stamp;
unsigned char nohz_balance_kick;
#endif
int skip_clock_update;
/* capture load from *all* tasks on this cpu: */
struct load_weight load;
unsigned long nr_load_updates;
u64 nr_switches;
struct cfs_rq cfs;
struct rt_rq rt;
#ifdef CONFIG_FAIR_GROUP_SCHED
/* list of leaf cfs_rq on this cpu: */
struct list_head leaf_cfs_rq_list;
#endif
#ifdef CONFIG_RT_GROUP_SCHED
struct list_head leaf_rt_rq_list;
#endif
/*
* This is part of a global counter where only the total sum
* over all CPUs matters. A task can increase this counter on
* one CPU and if it got migrated afterwards it may decrease
* it on another CPU. Always updated under the runqueue lock:
*/
unsigned long nr_uninterruptible;
struct task_struct *curr, *idle, *stop;
unsigned long next_balance;
struct mm_struct *prev_mm;
u64 clock;
u64 clock_task;
atomic_t nr_iowait;
#ifdef CONFIG_SMP
struct root_domain *rd;
struct sched_domain *sd;
unsigned long cpu_power;
unsigned char idle_at_tick;
/* For active balancing */
int post_schedule;
int active_balance;
int push_cpu;
struct cpu_stop_work active_balance_work;
/* cpu of this runqueue: */
int cpu;
int online;
unsigned long avg_load_per_task;
u64 rt_avg;
u64 age_stamp;
u64 idle_stamp;
u64 avg_idle;
#endif
#ifdef CONFIG_IRQ_TIME_ACCOUNTING
u64 prev_irq_time;
#endif
/* calc_load related fields */
unsigned long calc_load_update;
long calc_load_active;
#ifdef CONFIG_SCHED_HRTICK
#ifdef CONFIG_SMP
int hrtick_csd_pending;
struct call_single_data hrtick_csd;
#endif
struct hrtimer hrtick_timer;
#endif
#ifdef CONFIG_SCHEDSTATS
/* latency stats */
struct sched_info rq_sched_info;
unsigned long long rq_cpu_time;
/* could above be rq->cfs_rq.exec_clock + rq->rt_rq.rt_runtime ? */
/* sys_sched_yield() stats */
unsigned int yld_count;
/* schedule() stats */
unsigned int sched_switch;
unsigned int sched_count;
unsigned int sched_goidle;
/* try_to_wake_up() stats */
unsigned int ttwu_count;
unsigned int ttwu_local;
#endif
#ifdef CONFIG_SMP
struct task_struct *wake_list;
#endif
};
static DEFINE_PER_CPU_SHARED_ALIGNED(struct rq, runqueues);
static void check_preempt_curr(struct rq *rq, struct task_struct *p, int flags);
static inline int cpu_of(struct rq *rq)
{
#ifdef CONFIG_SMP
return rq->cpu;
#else
return 0;
#endif
}
#define rcu_dereference_check_sched_domain(p) \
rcu_dereference_check((p), \
rcu_read_lock_held() || \
lockdep_is_held(&sched_domains_mutex))
/*
* The domain tree (rq->sd) is protected by RCU's quiescent state transition.
* See detach_destroy_domains: synchronize_sched for details.
*
* The domain tree of any CPU may only be accessed from within
* preempt-disabled sections.
*/
#define for_each_domain(cpu, __sd) \
for (__sd = rcu_dereference_check_sched_domain(cpu_rq(cpu)->sd); __sd; __sd = __sd->parent)
#define cpu_rq(cpu) (&per_cpu(runqueues, (cpu)))
#define this_rq() (&__get_cpu_var(runqueues))
#define task_rq(p) cpu_rq(task_cpu(p))
#define cpu_curr(cpu) (cpu_rq(cpu)->curr)
#define raw_rq() (&__raw_get_cpu_var(runqueues))
#ifdef CONFIG_CGROUP_SCHED
/*
* Return the group to which this tasks belongs.
*
* We use task_subsys_state_check() and extend the RCU verification with
* pi->lock and rq->lock because cpu_cgroup_attach() holds those locks for each
* task it moves into the cgroup. Therefore by holding either of those locks,
* we pin the task to the current cgroup.
*/
static inline struct task_group *task_group(struct task_struct *p)
{
struct task_group *tg;
struct cgroup_subsys_state *css;
css = task_subsys_state_check(p, cpu_cgroup_subsys_id,
lockdep_is_held(&p->pi_lock) ||
lockdep_is_held(&task_rq(p)->lock));
tg = container_of(css, struct task_group, css);
return autogroup_task_group(p, tg);
}
/* Change a task's cfs_rq and parent entity if it moves across CPUs/groups */
static inline void set_task_rq(struct task_struct *p, unsigned int cpu)
{
#ifdef CONFIG_FAIR_GROUP_SCHED
p->se.cfs_rq = task_group(p)->cfs_rq[cpu];
p->se.parent = task_group(p)->se[cpu];
#endif
#ifdef CONFIG_RT_GROUP_SCHED
p->rt.rt_rq = task_group(p)->rt_rq[cpu];
p->rt.parent = task_group(p)->rt_se[cpu];
#endif
}
#else /* CONFIG_CGROUP_SCHED */
static inline void set_task_rq(struct task_struct *p, unsigned int cpu) { }
static inline struct task_group *task_group(struct task_struct *p)
{
return NULL;
}
#endif /* CONFIG_CGROUP_SCHED */
static void update_rq_clock_task(struct rq *rq, s64 delta);
static void update_rq_clock(struct rq *rq)
{
s64 delta;
if (rq->skip_clock_update > 0)
return;
delta = sched_clock_cpu(cpu_of(rq)) - rq->clock;
rq->clock += delta;
update_rq_clock_task(rq, delta);
}
/*
* Tunables that become constants when CONFIG_SCHED_DEBUG is off:
*/
#ifdef CONFIG_SCHED_DEBUG
# define const_debug __read_mostly
#else
# define const_debug static const
#endif
/**
* runqueue_is_locked - Returns true if the current cpu runqueue is locked
* @cpu: the processor in question.
*
* This interface allows printk to be called with the runqueue lock
* held and know whether or not it is OK to wake up the klogd.
*/
int runqueue_is_locked(int cpu)
{
return raw_spin_is_locked(&cpu_rq(cpu)->lock);
}
/*
* Debugging: various feature bits
*/
#define SCHED_FEAT(name, enabled) \
__SCHED_FEAT_##name ,
enum {
#include "sched_features.h"
};
#undef SCHED_FEAT
#define SCHED_FEAT(name, enabled) \
(1UL << __SCHED_FEAT_##name) * enabled |
const_debug unsigned int sysctl_sched_features =
#include "sched_features.h"
0;
#undef SCHED_FEAT
#ifdef CONFIG_SCHED_DEBUG
#define SCHED_FEAT(name, enabled) \
#name ,
static __read_mostly char *sched_feat_names[] = {
#include "sched_features.h"
NULL
};
#undef SCHED_FEAT
static int sched_feat_show(struct seq_file *m, void *v)
{
int i;
for (i = 0; sched_feat_names[i]; i++) {
if (!(sysctl_sched_features & (1UL << i)))
seq_puts(m, "NO_");
seq_printf(m, "%s ", sched_feat_names[i]);
}
seq_puts(m, "\n");
return 0;
}
static ssize_t
sched_feat_write(struct file *filp, const char __user *ubuf,
size_t cnt, loff_t *ppos)
{
char buf[64];
char *cmp;
int neg = 0;
int i;
if (cnt > 63)
cnt = 63;
if (copy_from_user(&buf, ubuf, cnt))
return -EFAULT;
buf[cnt] = 0;
cmp = strstrip(buf);
if (strncmp(cmp, "NO_", 3) == 0) {
neg = 1;
cmp += 3;
}
for (i = 0; sched_feat_names[i]; i++) {
if (strcmp(cmp, sched_feat_names[i]) == 0) {
if (neg)
sysctl_sched_features &= ~(1UL << i);
else
sysctl_sched_features |= (1UL << i);
break;
}
}
if (!sched_feat_names[i])
return -EINVAL;
*ppos += cnt;
return cnt;
}
static int sched_feat_open(struct inode *inode, struct file *filp)
{
return single_open(filp, sched_feat_show, NULL);
}
static const struct file_operations sched_feat_fops = {
.open = sched_feat_open,
.write = sched_feat_write,
.read = seq_read,
.llseek = seq_lseek,
.release = single_release,
};
static __init int sched_init_debug(void)
{
debugfs_create_file("sched_features", 0644, NULL, NULL,
&sched_feat_fops);
return 0;
}
late_initcall(sched_init_debug);
#endif
#define sched_feat(x) (sysctl_sched_features & (1UL << __SCHED_FEAT_##x))
/*
* Number of tasks to iterate in a single balance run.
* Limited because this is done with IRQs disabled.
*/
const_debug unsigned int sysctl_sched_nr_migrate = 32;
/*
* period over which we average the RT time consumption, measured
* in ms.
*
* default: 1s
*/
const_debug unsigned int sysctl_sched_time_avg = MSEC_PER_SEC;
/*
* period over which we measure -rt task cpu usage in us.
* default: 1s
*/
unsigned int sysctl_sched_rt_period = 1000000;
static __read_mostly int scheduler_running;
/*
* part of the period that we allow rt tasks to run in us.
* default: 0.95s
*/
int sysctl_sched_rt_runtime = 950000;
static inline u64 global_rt_period(void)
{
return (u64)sysctl_sched_rt_period * NSEC_PER_USEC;
}
static inline u64 global_rt_runtime(void)
{
if (sysctl_sched_rt_runtime < 0)
return RUNTIME_INF;
return (u64)sysctl_sched_rt_runtime * NSEC_PER_USEC;
}
#ifndef prepare_arch_switch
# define prepare_arch_switch(next) do { } while (0)
#endif
#ifndef finish_arch_switch
# define finish_arch_switch(prev) do { } while (0)
#endif
static inline int task_current(struct rq *rq, struct task_struct *p)
{
return rq->curr == p;
}
static inline int task_running(struct rq *rq, struct task_struct *p)
{
#ifdef CONFIG_SMP
return p->on_cpu;
#else
return task_current(rq, p);
#endif
}
#ifndef __ARCH_WANT_UNLOCKED_CTXSW
static inline void prepare_lock_switch(struct rq *rq, struct task_struct *next)
{
#ifdef CONFIG_SMP
/*
* We can optimise this out completely for !SMP, because the
* SMP rebalancing from interrupt is the only thing that cares
* here.
*/
next->on_cpu = 1;
#endif
}
static inline void finish_lock_switch(struct rq *rq, struct task_struct *prev)
{
#ifdef CONFIG_SMP
/*
* After ->on_cpu is cleared, the task can be moved to a different CPU.
* We must ensure this doesn't happen until the switch is completely
* finished.
*/
smp_wmb();
prev->on_cpu = 0;
#endif
#ifdef CONFIG_DEBUG_SPINLOCK
/* this is a valid case when another task releases the spinlock */
rq->lock.owner = current;
#endif
/*
* If we are tracking spinlock dependencies then we have to
* fix up the runqueue lock - which gets 'carried over' from
* prev into current:
*/
spin_acquire(&rq->lock.dep_map, 0, 0, _THIS_IP_);
raw_spin_unlock_irq(&rq->lock);
}
#else /* __ARCH_WANT_UNLOCKED_CTXSW */
static inline void prepare_lock_switch(struct rq *rq, struct task_struct *next)
{
#ifdef CONFIG_SMP
/*
* We can optimise this out completely for !SMP, because the
* SMP rebalancing from interrupt is the only thing that cares
* here.
*/
next->on_cpu = 1;
#endif
#ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW
raw_spin_unlock_irq(&rq->lock);
#else
raw_spin_unlock(&rq->lock);
#endif
}
static inline void finish_lock_switch(struct rq *rq, struct task_struct *prev)
{
#ifdef CONFIG_SMP
/*
* After ->on_cpu is cleared, the task can be moved to a different CPU.
* We must ensure this doesn't happen until the switch is completely
* finished.
*/
smp_wmb();
prev->on_cpu = 0;
#endif
#ifndef __ARCH_WANT_INTERRUPTS_ON_CTXSW
local_irq_enable();
#endif
}
#endif /* __ARCH_WANT_UNLOCKED_CTXSW */
/*
* __task_rq_lock - lock the rq @p resides on.
*/
static inline struct rq *__task_rq_lock(struct task_struct *p)
__acquires(rq->lock)
{
struct rq *rq;
lockdep_assert_held(&p->pi_lock);
for (;;) {
rq = task_rq(p);
raw_spin_lock(&rq->lock);
if (likely(rq == task_rq(p)))
return rq;
raw_spin_unlock(&rq->lock);
}
}
/*
* task_rq_lock - lock p->pi_lock and lock the rq @p resides on.
*/
static struct rq *task_rq_lock(struct task_struct *p, unsigned long *flags)
__acquires(p->pi_lock)
__acquires(rq->lock)
{
struct rq *rq;
for (;;) {
raw_spin_lock_irqsave(&p->pi_lock, *flags);
rq = task_rq(p);
raw_spin_lock(&rq->lock);
if (likely(rq == task_rq(p)))
return rq;
raw_spin_unlock(&rq->lock);
raw_spin_unlock_irqrestore(&p->pi_lock, *flags);
}
}
static void __task_rq_unlock(struct rq *rq)
__releases(rq->lock)
{
raw_spin_unlock(&rq->lock);
}
static inline void
task_rq_unlock(struct rq *rq, struct task_struct *p, unsigned long *flags)
__releases(rq->lock)
__releases(p->pi_lock)
{
raw_spin_unlock(&rq->lock);
raw_spin_unlock_irqrestore(&p->pi_lock, *flags);
}
/*
* this_rq_lock - lock this runqueue and disable interrupts.
*/
static struct rq *this_rq_lock(void)
__acquires(rq->lock)
{
struct rq *rq;
local_irq_disable();
rq = this_rq();
raw_spin_lock(&rq->lock);
return rq;
}
#ifdef CONFIG_SCHED_HRTICK
/*
* Use HR-timers to deliver accurate preemption points.
*
* Its all a bit involved since we cannot program an hrt while holding the
* rq->lock. So what we do is store a state in in rq->hrtick_* and ask for a
* reschedule event.
*
* When we get rescheduled we reprogram the hrtick_timer outside of the
* rq->lock.
*/
/*
* Use hrtick when:
* - enabled by features
* - hrtimer is actually high res
*/
static inline int hrtick_enabled(struct rq *rq)
{
if (!sched_feat(HRTICK))
return 0;
if (!cpu_active(cpu_of(rq)))
return 0;
return hrtimer_is_hres_active(&rq->hrtick_timer);
}
static void hrtick_clear(struct rq *rq)
{
if (hrtimer_active(&rq->hrtick_timer))
hrtimer_cancel(&rq->hrtick_timer);
}
/*
* High-resolution timer tick.
* Runs from hardirq context with interrupts disabled.
*/
static enum hrtimer_restart hrtick(struct hrtimer *timer)
{
struct rq *rq = container_of(timer, struct rq, hrtick_timer);
WARN_ON_ONCE(cpu_of(rq) != smp_processor_id());
raw_spin_lock(&rq->lock);
update_rq_clock(rq);
rq->curr->sched_class->task_tick(rq, rq->curr, 1);
raw_spin_unlock(&rq->lock);
return HRTIMER_NORESTART;
}
#ifdef CONFIG_SMP
/*
* called from hardirq (IPI) context
*/
static void __hrtick_start(void *arg)
{
struct rq *rq = arg;
raw_spin_lock(&rq->lock);
hrtimer_restart(&rq->hrtick_timer);
rq->hrtick_csd_pending = 0;
raw_spin_unlock(&rq->lock);
}
/*
* Called to set the hrtick timer state.
*
* called with rq->lock held and irqs disabled
*/
static void hrtick_start(struct rq *rq, u64 delay)
{
struct hrtimer *timer = &rq->hrtick_timer;
ktime_t time = ktime_add_ns(timer->base->get_time(), delay);
hrtimer_set_expires(timer, time);
if (rq == this_rq()) {
hrtimer_restart(timer);
} else if (!rq->hrtick_csd_pending) {
__smp_call_function_single(cpu_of(rq), &rq->hrtick_csd, 0);
rq->hrtick_csd_pending = 1;
}
}
static int
hotplug_hrtick(struct notifier_block *nfb, unsigned long action, void *hcpu)
{
int cpu = (int)(long)hcpu;
switch (action) {
case CPU_UP_CANCELED:
case CPU_UP_CANCELED_FROZEN:
case CPU_DOWN_PREPARE:
case CPU_DOWN_PREPARE_FROZEN:
case CPU_DEAD:
case CPU_DEAD_FROZEN:
hrtick_clear(cpu_rq(cpu));
return NOTIFY_OK;
}
return NOTIFY_DONE;
}
static __init void init_hrtick(void)
{
hotcpu_notifier(hotplug_hrtick, 0);
}
#else
/*
* Called to set the hrtick timer state.
*
* called with rq->lock held and irqs disabled
*/
static void hrtick_start(struct rq *rq, u64 delay)
{
__hrtimer_start_range_ns(&rq->hrtick_timer, ns_to_ktime(delay), 0,
HRTIMER_MODE_REL_PINNED, 0);
}
static inline void init_hrtick(void)
{
}
#endif /* CONFIG_SMP */
static void init_rq_hrtick(struct rq *rq)
{
#ifdef CONFIG_SMP
rq->hrtick_csd_pending = 0;
rq->hrtick_csd.flags = 0;
rq->hrtick_csd.func = __hrtick_start;
rq->hrtick_csd.info = rq;
#endif
hrtimer_init(&rq->hrtick_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
rq->hrtick_timer.function = hrtick;
}
#else /* CONFIG_SCHED_HRTICK */
static inline void hrtick_clear(struct rq *rq)
{
}
static inline void init_rq_hrtick(struct rq *rq)
{
}
static inline void init_hrtick(void)
{
}
#endif /* CONFIG_SCHED_HRTICK */
/*
* resched_task - mark a task 'to be rescheduled now'.
*
* On UP this means the setting of the need_resched flag, on SMP it
* might also involve a cross-CPU call to trigger the scheduler on
* the target CPU.
*/
#ifdef CONFIG_SMP
#ifndef tsk_is_polling
#define tsk_is_polling(t) test_tsk_thread_flag(t, TIF_POLLING_NRFLAG)
#endif
static void resched_task(struct task_struct *p)
{
int cpu;
assert_raw_spin_locked(&task_rq(p)->lock);
if (test_tsk_need_resched(p))
return;
set_tsk_need_resched(p);
cpu = task_cpu(p);
if (cpu == smp_processor_id())
return;
/* NEED_RESCHED must be visible before we test polling */
smp_mb();
if (!tsk_is_polling(p))
smp_send_reschedule(cpu);
}
static void resched_cpu(int cpu)
{
struct rq *rq = cpu_rq(cpu);
unsigned long flags;
if (!raw_spin_trylock_irqsave(&rq->lock, flags))
return;
resched_task(cpu_curr(cpu));
raw_spin_unlock_irqrestore(&rq->lock, flags);
}
#ifdef CONFIG_NO_HZ
/*
* In the semi idle case, use the nearest busy cpu for migrating timers
* from an idle cpu. This is good for power-savings.
*
* We don't do similar optimization for completely idle system, as
* selecting an idle cpu will add more delays to the timers than intended
* (as that cpu's timer base may not be uptodate wrt jiffies etc).
*/
int get_nohz_timer_target(void)
{
int cpu = smp_processor_id();
int i;
struct sched_domain *sd;
rcu_read_lock();
for_each_domain(cpu, sd) {
for_each_cpu(i, sched_domain_span(sd)) {
if (!idle_cpu(i)) {
cpu = i;
goto unlock;
}
}
}
unlock:
rcu_read_unlock();
return cpu;
}
/*
* When add_timer_on() enqueues a timer into the timer wheel of an
* idle CPU then this timer might expire before the next timer event
* which is scheduled to wake up that CPU. In case of a completely
* idle system the next event might even be infinite time into the
* future. wake_up_idle_cpu() ensures that the CPU is woken up and
* leaves the inner idle loop so the newly added timer is taken into
* account when the CPU goes back to idle and evaluates the timer
* wheel for the next timer event.
*/
void wake_up_idle_cpu(int cpu)
{
struct rq *rq = cpu_rq(cpu);
if (cpu == smp_processor_id())
return;
/*
* This is safe, as this function is called with the timer
* wheel base lock of (cpu) held. When the CPU is on the way
* to idle and has not yet set rq->curr to idle then it will
* be serialized on the timer wheel base lock and take the new
* timer into account automatically.
*/
if (rq->curr != rq->idle)
return;
/*
* We can set TIF_RESCHED on the idle task of the other CPU
* lockless. The worst case is that the other CPU runs the
* idle task through an additional NOOP schedule()
*/
set_tsk_need_resched(rq->idle);
/* NEED_RESCHED must be visible before we test polling */
smp_mb();
if (!tsk_is_polling(rq->idle))
smp_send_reschedule(cpu);
}
#endif /* CONFIG_NO_HZ */
static u64 sched_avg_period(void)
{
return (u64)sysctl_sched_time_avg * NSEC_PER_MSEC / 2;
}
static void sched_avg_update(struct rq *rq)
{
s64 period = sched_avg_period();
while ((s64)(rq->clock - rq->age_stamp) > period) {
/*
* Inline assembly required to prevent the compiler
* optimising this loop into a divmod call.
* See __iter_div_u64_rem() for another example of this.
*/
asm("" : "+rm" (rq->age_stamp));
rq->age_stamp += period;
rq->rt_avg /= 2;
}
}
static void sched_rt_avg_update(struct rq *rq, u64 rt_delta)
{
rq->rt_avg += rt_delta;
sched_avg_update(rq);
}
#else /* !CONFIG_SMP */
static void resched_task(struct task_struct *p)
{
assert_raw_spin_locked(&task_rq(p)->lock);
set_tsk_need_resched(p);
}
static void sched_rt_avg_update(struct rq *rq, u64 rt_delta)
{
}
static void sched_avg_update(struct rq *rq)
{
}
#endif /* CONFIG_SMP */
#if BITS_PER_LONG == 32
# define WMULT_CONST (~0UL)
#else
# define WMULT_CONST (1UL << 32)
#endif
#define WMULT_SHIFT 32
/*
* Shift right and round:
*/
#define SRR(x, y) (((x) + (1UL << ((y) - 1))) >> (y))
/*
* delta *= weight / lw
*/
static unsigned long
calc_delta_mine(unsigned long delta_exec, unsigned long weight,
struct load_weight *lw)
{
u64 tmp;
/*
* weight can be less than 2^SCHED_LOAD_RESOLUTION for task group sched
* entities since MIN_SHARES = 2. Treat weight as 1 if less than
* 2^SCHED_LOAD_RESOLUTION.
*/
if (likely(weight > (1UL << SCHED_LOAD_RESOLUTION)))
tmp = (u64)delta_exec * scale_load_down(weight);
else
tmp = (u64)delta_exec;
if (!lw->inv_weight) {
unsigned long 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;
}
/*
* Check whether we'd overflow the 64-bit multiplication:
*/
if (unlikely(tmp > WMULT_CONST))
tmp = SRR(SRR(tmp, WMULT_SHIFT/2) * lw->inv_weight,
WMULT_SHIFT/2);
else
tmp = SRR(tmp * lw->inv_weight, WMULT_SHIFT);
return (unsigned long)min(tmp, (u64)(unsigned long)LONG_MAX);
}
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;
}
/*
* To aid in avoiding the subversion of "niceness" due to uneven distribution
* of tasks with abnormal "nice" values across CPUs the contribution that
* each task makes to its run queue's load is weighted according to its
* scheduling class and "nice" value. For SCHED_NORMAL tasks this is just a
* scaled version of the new time slice allocation that they receive on time
* slice expiry etc.
*/
#define WEIGHT_IDLEPRIO 3
#define WMULT_IDLEPRIO 1431655765
/*
* Nice levels are multiplicative, with a gentle 10% change for every
* nice level changed. I.e. when a CPU-bound task goes from nice 0 to
* nice 1, it will get ~10% less CPU time than another CPU-bound task
* that remained on nice 0.
*
* The "10% effect" is relative and cumulative: from _any_ nice level,
* if you go up 1 level, it's -10% CPU usage, if you go down 1 level
* it's +10% CPU usage. (to achieve that we use a multiplier of 1.25.
* If a task goes up by ~10% and another task goes down by ~10% then
* the relative distance between them is ~25%.)
*/
static const int prio_to_weight[40] = {
/* -20 */ 88761, 71755, 56483, 46273, 36291,
/* -15 */ 29154, 23254, 18705, 14949, 11916,
/* -10 */ 9548, 7620, 6100, 4904, 3906,
/* -5 */ 3121, 2501, 1991, 1586, 1277,
/* 0 */ 1024, 820, 655, 526, 423,
/* 5 */ 335, 272, 215, 172, 137,
/* 10 */ 110, 87, 70, 56, 45,
/* 15 */ 36, 29, 23, 18, 15,
};
/*
* Inverse (2^32/x) values of the prio_to_weight[] array, precalculated.
*
* In cases where the weight does not change often, we can use the
* precalculated inverse to speed up arithmetics by turning divisions
* into multiplications:
*/
static const u32 prio_to_wmult[40] = {
/* -20 */ 48388, 59856, 76040, 92818, 118348,
/* -15 */ 147320, 184698, 229616, 287308, 360437,
/* -10 */ 449829, 563644, 704093, 875809, 1099582,
/* -5 */ 1376151, 1717300, 2157191, 2708050, 3363326,
/* 0 */ 4194304, 5237765, 6557202, 8165337, 10153587,
/* 5 */ 12820798, 15790321, 19976592, 24970740, 31350126,
/* 10 */ 39045157, 49367440, 61356676, 76695844, 95443717,
/* 15 */ 119304647, 148102320, 186737708, 238609294, 286331153,
};
/* Time spent by the tasks of the cpu accounting group executing in ... */
enum cpuacct_stat_index {
CPUACCT_STAT_USER, /* ... user mode */
CPUACCT_STAT_SYSTEM, /* ... kernel mode */
CPUACCT_STAT_NSTATS,
};
#ifdef CONFIG_CGROUP_CPUACCT
static void cpuacct_charge(struct task_struct *tsk, u64 cputime);
static void cpuacct_update_stats(struct task_struct *tsk,
enum cpuacct_stat_index idx, cputime_t val);
#else
static inline void cpuacct_charge(struct task_struct *tsk, u64 cputime) {}
static inline void cpuacct_update_stats(struct task_struct *tsk,
enum cpuacct_stat_index idx, cputime_t val) {}
#endif
static inline void inc_cpu_load(struct rq *rq, unsigned long load)
{
update_load_add(&rq->load, load);
}
static inline void dec_cpu_load(struct rq *rq, unsigned long load)
{
update_load_sub(&rq->load, load);
}
#if (defined(CONFIG_SMP) && defined(CONFIG_FAIR_GROUP_SCHED)) || defined(CONFIG_RT_GROUP_SCHED)
typedef int (*tg_visitor)(struct task_group *, void *);
/*
* Iterate the full tree, calling @down when first entering a node and @up when
* leaving it for the final time.
*/
static int walk_tg_tree(tg_visitor down, tg_visitor up, void *data)
{
struct task_group *parent, *child;
int ret;
rcu_read_lock();
parent = &root_task_group;
down:
ret = (*down)(parent, data);
if (ret)
goto out_unlock;
list_for_each_entry_rcu(child, &parent->children, siblings) {
parent = child;
goto down;
up:
continue;
}
ret = (*up)(parent, data);
if (ret)
goto out_unlock;
child = parent;
parent = parent->parent;
if (parent)
goto up;
out_unlock:
rcu_read_unlock();
return ret;
}
static int tg_nop(struct task_group *tg, void *data)
{
return 0;
}
#endif
#ifdef CONFIG_SMP
/* Used instead of source_load when we know the type == 0 */
static unsigned long weighted_cpuload(const int cpu)
{
return cpu_rq(cpu)->load.weight;
}
/*
* 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 power_of(int cpu)
{
return cpu_rq(cpu)->cpu_power;
}
static int task_hot(struct task_struct *p, u64 now, struct sched_domain *sd);
static unsigned long cpu_avg_load_per_task(int cpu)
{
struct rq *rq = cpu_rq(cpu);
unsigned long nr_running = ACCESS_ONCE(rq->nr_running);
if (nr_running)
rq->avg_load_per_task = rq->load.weight / nr_running;
else
rq->avg_load_per_task = 0;
return rq->avg_load_per_task;
}
#ifdef CONFIG_PREEMPT
static void double_rq_lock(struct rq *rq1, struct rq *rq2);
/*
* fair double_lock_balance: Safely acquires both rq->locks in a fair
* way at the expense of forcing extra atomic operations in all
* invocations. This assures that the double_lock is acquired using the
* same underlying policy as the spinlock_t on this architecture, which
* reduces latency compared to the unfair variant below. However, it
* also adds more overhead and therefore may reduce throughput.
*/
static inline int _double_lock_balance(struct rq *this_rq, struct rq *busiest)
__releases(this_rq->lock)
__acquires(busiest->lock)
__acquires(this_rq->lock)
{
raw_spin_unlock(&this_rq->lock);
double_rq_lock(this_rq, busiest);
return 1;
}
#else
/*
* Unfair double_lock_balance: Optimizes throughput at the expense of
* latency by eliminating extra atomic operations when the locks are
* already in proper order on entry. This favors lower cpu-ids and will
* grant the double lock to lower cpus over higher ids under contention,
* regardless of entry order into the function.
*/
static int _double_lock_balance(struct rq *this_rq, struct rq *busiest)
__releases(this_rq->lock)
__acquires(busiest->lock)
__acquires(this_rq->lock)
{
int ret = 0;
if (unlikely(!raw_spin_trylock(&busiest->lock))) {
if (busiest < this_rq) {
raw_spin_unlock(&this_rq->lock);
raw_spin_lock(&busiest->lock);
raw_spin_lock_nested(&this_rq->lock,
SINGLE_DEPTH_NESTING);
ret = 1;
} else
raw_spin_lock_nested(&busiest->lock,
SINGLE_DEPTH_NESTING);
}
return ret;
}
#endif /* CONFIG_PREEMPT */
/*
* double_lock_balance - lock the busiest runqueue, this_rq is locked already.
*/
static int double_lock_balance(struct rq *this_rq, struct rq *busiest)
{
if (unlikely(!irqs_disabled())) {
/* printk() doesn't work good under rq->lock */
raw_spin_unlock(&this_rq->lock);
BUG_ON(1);
}
return _double_lock_balance(this_rq, busiest);
}
static inline void double_unlock_balance(struct rq *this_rq, struct rq *busiest)
__releases(busiest->lock)
{
raw_spin_unlock(&busiest->lock);
lock_set_subclass(&this_rq->lock.dep_map, 0, _RET_IP_);
}
/*
* double_rq_lock - safely lock two runqueues
*
* Note this does not disable interrupts like task_rq_lock,
* you need to do so manually before calling.
*/
static void double_rq_lock(struct rq *rq1, struct rq *rq2)
__acquires(rq1->lock)
__acquires(rq2->lock)
{
BUG_ON(!irqs_disabled());
if (rq1 == rq2) {
raw_spin_lock(&rq1->lock);
__acquire(rq2->lock); /* Fake it out ;) */
} else {
if (rq1 < rq2) {
raw_spin_lock(&rq1->lock);
raw_spin_lock_nested(&rq2->lock, SINGLE_DEPTH_NESTING);
} else {
raw_spin_lock(&rq2->lock);
raw_spin_lock_nested(&rq1->lock, SINGLE_DEPTH_NESTING);
}
}
}
/*
* double_rq_unlock - safely unlock two runqueues
*
* Note this does not restore interrupts like task_rq_unlock,
* you need to do so manually after calling.
*/
static void double_rq_unlock(struct rq *rq1, struct rq *rq2)
__releases(rq1->lock)
__releases(rq2->lock)
{
raw_spin_unlock(&rq1->lock);
if (rq1 != rq2)
raw_spin_unlock(&rq2->lock);
else
__release(rq2->lock);
}
#else /* CONFIG_SMP */
/*
* double_rq_lock - safely lock two runqueues
*
* Note this does not disable interrupts like task_rq_lock,
* you need to do so manually before calling.
*/
static void double_rq_lock(struct rq *rq1, struct rq *rq2)
__acquires(rq1->lock)
__acquires(rq2->lock)
{
BUG_ON(!irqs_disabled());
BUG_ON(rq1 != rq2);
raw_spin_lock(&rq1->lock);
__acquire(rq2->lock); /* Fake it out ;) */
}
/*
* double_rq_unlock - safely unlock two runqueues
*
* Note this does not restore interrupts like task_rq_unlock,
* you need to do so manually after calling.
*/
static void double_rq_unlock(struct rq *rq1, struct rq *rq2)
__releases(rq1->lock)
__releases(rq2->lock)
{
BUG_ON(rq1 != rq2);
raw_spin_unlock(&rq1->lock);
__release(rq2->lock);
}
#endif
static void calc_load_account_idle(struct rq *this_rq);
static void update_sysctl(void);
static int get_update_sysctl_factor(void);
static void update_cpu_load(struct rq *this_rq);
static inline void __set_task_cpu(struct task_struct *p, unsigned int cpu)
{
set_task_rq(p, cpu);
#ifdef CONFIG_SMP
/*
* After ->cpu is set up to a new value, task_rq_lock(p, ...) can be
* successfuly executed on another CPU. We must ensure that updates of
* per-task data have been completed by this moment.
*/
smp_wmb();
task_thread_info(p)->cpu = cpu;
#endif
}
static const struct sched_class rt_sched_class;
#define sched_class_highest (&stop_sched_class)
#define for_each_class(class) \
for (class = sched_class_highest; class; class = class->next)
#include "sched_stats.h"
static void inc_nr_running(struct rq *rq)
{
rq->nr_running++;
}
static void dec_nr_running(struct rq *rq)
{
rq->nr_running--;
}
static void set_load_weight(struct task_struct *p)
{
int prio = p->static_prio - MAX_RT_PRIO;
struct load_weight *load = &p->se.load;
/*
* SCHED_IDLE tasks get minimal weight:
*/
if (p->policy == SCHED_IDLE) {
load->weight = scale_load(WEIGHT_IDLEPRIO);
load->inv_weight = WMULT_IDLEPRIO;
return;
}
load->weight = scale_load(prio_to_weight[prio]);
load->inv_weight = prio_to_wmult[prio];
}
static void enqueue_task(struct rq *rq, struct task_struct *p, int flags)
{
update_rq_clock(rq);
sched_info_queued(p);
p->sched_class->enqueue_task(rq, p, flags);
}
static void dequeue_task(struct rq *rq, struct task_struct *p, int flags)
{
update_rq_clock(rq);
sched_info_dequeued(p);
p->sched_class->dequeue_task(rq, p, flags);
}
/*
* activate_task - move a task to the runqueue.
*/
static void activate_task(struct rq *rq, struct task_struct *p, int flags)
{
if (task_contributes_to_load(p))
rq->nr_uninterruptible--;
enqueue_task(rq, p, flags);
inc_nr_running(rq);
}
/*
* deactivate_task - remove a task from the runqueue.
*/
static void deactivate_task(struct rq *rq, struct task_struct *p, int flags)
{
if (task_contributes_to_load(p))
rq->nr_uninterruptible++;
dequeue_task(rq, p, flags);
dec_nr_running(rq);
}
#ifdef CONFIG_IRQ_TIME_ACCOUNTING
/*
* There are no locks covering percpu hardirq/softirq time.
* They are only modified in account_system_vtime, on corresponding CPU
* with interrupts disabled. So, writes are safe.
* They are read and saved off onto struct rq in update_rq_clock().
* This may result in other CPU reading this CPU's irq time and can
* race with irq/account_system_vtime on this CPU. We would either get old
* or new value with a side effect of accounting a slice of irq time to wrong
* task when irq is in progress while we read rq->clock. That is a worthy
* compromise in place of having locks on each irq in account_system_time.
*/
static DEFINE_PER_CPU(u64, cpu_hardirq_time);
static DEFINE_PER_CPU(u64, cpu_softirq_time);
static DEFINE_PER_CPU(u64, irq_start_time);
static int sched_clock_irqtime;
void enable_sched_clock_irqtime(void)
{
sched_clock_irqtime = 1;
}
void disable_sched_clock_irqtime(void)
{
sched_clock_irqtime = 0;
}
#ifndef CONFIG_64BIT
static DEFINE_PER_CPU(seqcount_t, irq_time_seq);
static inline void irq_time_write_begin(void)
{
__this_cpu_inc(irq_time_seq.sequence);
smp_wmb();
}
static inline void irq_time_write_end(void)
{
smp_wmb();
__this_cpu_inc(irq_time_seq.sequence);
}
static inline u64 irq_time_read(int cpu)
{
u64 irq_time;
unsigned seq;
do {
seq = read_seqcount_begin(&per_cpu(irq_time_seq, cpu));
irq_time = per_cpu(cpu_softirq_time, cpu) +
per_cpu(cpu_hardirq_time, cpu);
} while (read_seqcount_retry(&per_cpu(irq_time_seq, cpu), seq));
return irq_time;
}
#else /* CONFIG_64BIT */
static inline void irq_time_write_begin(void)
{
}
static inline void irq_time_write_end(void)
{
}
static inline u64 irq_time_read(int cpu)
{
return per_cpu(cpu_softirq_time, cpu) + per_cpu(cpu_hardirq_time, cpu);
}
#endif /* CONFIG_64BIT */
/*
* Called before incrementing preempt_count on {soft,}irq_enter
* and before decrementing preempt_count on {soft,}irq_exit.
*/
void account_system_vtime(struct task_struct *curr)
{
unsigned long flags;
s64 delta;
int cpu;
if (!sched_clock_irqtime)
return;
local_irq_save(flags);
cpu = smp_processor_id();
delta = sched_clock_cpu(cpu) - __this_cpu_read(irq_start_time);
__this_cpu_add(irq_start_time, delta);
irq_time_write_begin();
/*
* We do not account for softirq time from ksoftirqd here.
* We want to continue accounting softirq time to ksoftirqd thread
* in that case, so as not to confuse scheduler with a special task
* that do not consume any time, but still wants to run.
*/
if (hardirq_count())
__this_cpu_add(cpu_hardirq_time, delta);
else if (in_serving_softirq() && curr != this_cpu_ksoftirqd())
__this_cpu_add(cpu_softirq_time, delta);
irq_time_write_end();
local_irq_restore(flags);
}
EXPORT_SYMBOL_GPL(account_system_vtime);
static void update_rq_clock_task(struct rq *rq, s64 delta)
{
s64 irq_delta;
irq_delta = irq_time_read(cpu_of(rq)) - rq->prev_irq_time;
/*
* Since irq_time is only updated on {soft,}irq_exit, we might run into
* this case when a previous update_rq_clock() happened inside a
* {soft,}irq region.
*
* When this happens, we stop ->clock_task and only update the
* prev_irq_time stamp to account for the part that fit, so that a next
* update will consume the rest. This ensures ->clock_task is
* monotonic.
*
* It does however cause some slight miss-attribution of {soft,}irq
* time, a more accurate solution would be to update the irq_time using
* the current rq->clock timestamp, except that would require using
* atomic ops.
*/
if (irq_delta > delta)
irq_delta = delta;
rq->prev_irq_time += irq_delta;
delta -= irq_delta;
rq->clock_task += delta;
if (irq_delta && sched_feat(NONIRQ_POWER))
sched_rt_avg_update(rq, irq_delta);
}
static int irqtime_account_hi_update(void)
{
struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat;
unsigned long flags;
u64 latest_ns;
int ret = 0;
local_irq_save(flags);
latest_ns = this_cpu_read(cpu_hardirq_time);
if (cputime64_gt(nsecs_to_cputime64(latest_ns), cpustat->irq))
ret = 1;
local_irq_restore(flags);
return ret;
}
static int irqtime_account_si_update(void)
{
struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat;
unsigned long flags;
u64 latest_ns;
int ret = 0;
local_irq_save(flags);
latest_ns = this_cpu_read(cpu_softirq_time);
if (cputime64_gt(nsecs_to_cputime64(latest_ns), cpustat->softirq))
ret = 1;
local_irq_restore(flags);
return ret;
}
#else /* CONFIG_IRQ_TIME_ACCOUNTING */
#define sched_clock_irqtime (0)
static void update_rq_clock_task(struct rq *rq, s64 delta)
{
rq->clock_task += delta;
}
#endif /* CONFIG_IRQ_TIME_ACCOUNTING */
#include "sched_idletask.c"
#include "sched_fair.c"
#include "sched_rt.c"
#include "sched_autogroup.c"
#include "sched_stoptask.c"
#ifdef CONFIG_SCHED_DEBUG
# include "sched_debug.c"
#endif
void sched_set_stop_task(int cpu, struct task_struct *stop)
{
struct sched_param param = { .sched_priority = MAX_RT_PRIO - 1 };
struct task_struct *old_stop = cpu_rq(cpu)->stop;
if (stop) {
/*
* Make it appear like a SCHED_FIFO task, its something
* userspace knows about and won't get confused about.
*
* Also, it will make PI more or less work without too
* much confusion -- but then, stop work should not
* rely on PI working anyway.
*/
sched_setscheduler_nocheck(stop, SCHED_FIFO, &param);
stop->sched_class = &stop_sched_class;
}
cpu_rq(cpu)->stop = stop;
if (old_stop) {
/*
* Reset it back to a normal scheduling class so that
* it can die in pieces.
*/
old_stop->sched_class = &rt_sched_class;
}
}
/*
* __normal_prio - return the priority that is based on the static prio
*/
static inline int __normal_prio(struct task_struct *p)
{
return p->static_prio;
}
/*
* Calculate the expected normal priority: i.e. priority
* without taking RT-inheritance into account. Might be
* boosted by interactivity modifiers. Changes upon fork,
* setprio syscalls, and whenever the interactivity
* estimator recalculates.
*/
static inline int normal_prio(struct task_struct *p)
{
int prio;
if (task_has_rt_policy(p))
prio = MAX_RT_PRIO-1 - p->rt_priority;
else
prio = __normal_prio(p);
return prio;
}
/*
* Calculate the current priority, i.e. the priority
* taken into account by the scheduler. This value might
* be boosted by RT tasks, or might be boosted by
* interactivity modifiers. Will be RT if the task got
* RT-boosted. If not then it returns p->normal_prio.
*/
static int effective_prio(struct task_struct *p)
{
p->normal_prio = normal_prio(p);
/*
* If we are RT tasks or we were boosted to RT priority,
* keep the priority unchanged. Otherwise, update priority
* to the normal priority:
*/
if (!rt_prio(p->prio))
return p->normal_prio;
return p->prio;
}
/**
* task_curr - is this task currently executing on a CPU?
* @p: the task in question.
*/
inline int task_curr(const struct task_struct *p)
{
return cpu_curr(task_cpu(p)) == p;
}
static inline void check_class_changed(struct rq *rq, struct task_struct *p,
const struct sched_class *prev_class,
int oldprio)
{
if (prev_class != p->sched_class) {
if (prev_class->switched_from)
prev_class->switched_from(rq, p);
p->sched_class->switched_to(rq, p);
} else if (oldprio != p->prio)
p->sched_class->prio_changed(rq, p, oldprio);
}
static void check_preempt_curr(struct rq *rq, struct task_struct *p, int flags)
{
const struct sched_class *class;
if (p->sched_class == rq->curr->sched_class) {
rq->curr->sched_class->check_preempt_curr(rq, p, flags);
} else {
for_each_class(class) {
if (class == rq->curr->sched_class)
break;
if (class == p->sched_class) {
resched_task(rq->curr);
break;
}
}
}
/*
* A queue event has occurred, and we're going to schedule. In
* this case, we can save a useless back to back clock update.
*/
if (rq->curr->on_rq && test_tsk_need_resched(rq->curr))
rq->skip_clock_update = 1;
}
#ifdef CONFIG_SMP
/*
* Is this task likely cache-hot:
*/
static int
task_hot(struct task_struct *p, u64 now, struct sched_domain *sd)
{
s64 delta;
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) && this_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 = now - p->se.exec_start;
return delta < (s64)sysctl_sched_migration_cost;
}
void set_task_cpu(struct task_struct *p, unsigned int new_cpu)
{
#ifdef CONFIG_SCHED_DEBUG
/*
* We should never call set_task_cpu() on a blocked task,
* ttwu() will sort out the placement.
*/
WARN_ON_ONCE(p->state != TASK_RUNNING && p->state != TASK_WAKING &&
!(task_thread_info(p)->preempt_count & PREEMPT_ACTIVE));
#ifdef CONFIG_LOCKDEP
/*
* The caller should hold either p->pi_lock or rq->lock, when changing
* a task's CPU. ->pi_lock for waking tasks, rq->lock for runnable tasks.
*
* sched_move_task() holds both and thus holding either pins the cgroup,
* see set_task_rq().
*
* Furthermore, all task_rq users should acquire both locks, see
* task_rq_lock().
*/
WARN_ON_ONCE(debug_locks && !(lockdep_is_held(&p->pi_lock) ||
lockdep_is_held(&task_rq(p)->lock)));
#endif
#endif
trace_sched_migrate_task(p, new_cpu);
if (task_cpu(p) != new_cpu) {
p->se.nr_migrations++;
perf_sw_event(PERF_COUNT_SW_CPU_MIGRATIONS, 1, NULL, 0);
}
__set_task_cpu(p, new_cpu);
}
struct migration_arg {
struct task_struct *task;
int dest_cpu;
};
static int migration_cpu_stop(void *data);
/*
* wait_task_inactive - wait for a thread to unschedule.
*
* If @match_state is nonzero, it's the @p->state value just checked and
* not expected to change. If it changes, i.e. @p might have woken up,
* then return zero. When we succeed in waiting for @p to be off its CPU,
* we return a positive number (its total switch count). If a second call
* a short while later returns the same number, the caller can be sure that
* @p has remained unscheduled the whole time.
*
* The caller must ensure that the task *will* unschedule sometime soon,
* else this function might spin for a *long* time. This function can't
* be called with interrupts off, or it may introduce deadlock with
* smp_call_function() if an IPI is sent by the same process we are
* waiting to become inactive.
*/
unsigned long wait_task_inactive(struct task_struct *p, long match_state)
{
unsigned long flags;
int running, on_rq;
unsigned long ncsw;
struct rq *rq;
for (;;) {
/*
* We do the initial early heuristics without holding
* any task-queue locks at all. We'll only try to get
* the runqueue lock when things look like they will
* work out!
*/
rq = task_rq(p);
/*
* If the task is actively running on another CPU
* still, just relax and busy-wait without holding
* any locks.
*
* NOTE! Since we don't hold any locks, it's not
* even sure that "rq" stays as the right runqueue!
* But we don't care, since "task_running()" will
* return false if the runqueue has changed and p
* is actually now running somewhere else!
*/
while (task_running(rq, p)) {
if (match_state && unlikely(p->state != match_state))
return 0;
cpu_relax();
}
/*
* Ok, time to look more closely! We need the rq
* lock now, to be *sure*. If we're wrong, we'll
* just go back and repeat.
*/
rq = task_rq_lock(p, &flags);
trace_sched_wait_task(p);
running = task_running(rq, p);
on_rq = p->on_rq;
ncsw = 0;
if (!match_state || p->state == match_state)
ncsw = p->nvcsw | LONG_MIN; /* sets MSB */
task_rq_unlock(rq, p, &flags);
/*
* If it changed from the expected state, bail out now.
*/
if (unlikely(!ncsw))
break;
/*
* Was it really running after all now that we
* checked with the proper locks actually held?
*
* Oops. Go back and try again..
*/
if (unlikely(running)) {
cpu_relax();
continue;
}
/*
* It's not enough that it's not actively running,
* it must be off the runqueue _entirely_, and not
* preempted!
*
* So if it was still runnable (but just not actively
* running right now), it's preempted, and we should
* yield - it could be a while.
*/
if (unlikely(on_rq)) {
ktime_t to = ktime_set(0, NSEC_PER_SEC/HZ);
set_current_state(TASK_UNINTERRUPTIBLE);
schedule_hrtimeout(&to, HRTIMER_MODE_REL);
continue;
}
/*
* Ahh, all good. It wasn't running, and it wasn't
* runnable, which means that it will never become
* running in the future either. We're all done!
*/
break;
}
return ncsw;
}
/***
* kick_process - kick a running thread to enter/exit the kernel
* @p: the to-be-kicked thread
*
* Cause a process which is running on another CPU to enter
* kernel-mode, without any delay. (to get signals handled.)
*
* NOTE: this function doesn't have to take the runqueue lock,
* because all it wants to ensure is that the remote task enters
* the kernel. If the IPI races and the task has been migrated
* to another CPU then no harm is done and the purpose has been
* achieved as well.
*/
void kick_process(struct task_struct *p)
{
int cpu;
preempt_disable();
cpu = task_cpu(p);
if ((cpu != smp_processor_id()) && task_curr(p))
smp_send_reschedule(cpu);
preempt_enable();
}
EXPORT_SYMBOL_GPL(kick_process);
#endif /* CONFIG_SMP */
#ifdef CONFIG_SMP
/*
* ->cpus_allowed is protected by both rq->lock and p->pi_lock
*/
static int select_fallback_rq(int cpu, struct task_struct *p)
{
int dest_cpu;
const struct cpumask *nodemask = cpumask_of_node(cpu_to_node(cpu));
/* Look for allowed, online CPU in same node. */
for_each_cpu_and(dest_cpu, nodemask, cpu_active_mask)
if (cpumask_test_cpu(dest_cpu, &p->cpus_allowed))
return dest_cpu;
/* Any allowed, online CPU? */
dest_cpu = cpumask_any_and(&p->cpus_allowed, cpu_active_mask);
if (dest_cpu < nr_cpu_ids)
return dest_cpu;
/* No more Mr. Nice Guy. */
dest_cpu = cpuset_cpus_allowed_fallback(p);
/*
* Don't tell them about moving exiting tasks or
* kernel threads (both mm NULL), since they never
* leave kernel.
*/
if (p->mm && printk_ratelimit()) {
printk(KERN_INFO "process %d (%s) no longer affine to cpu%d\n",
task_pid_nr(p), p->comm, cpu);
}
return dest_cpu;
}
/*
* The caller (fork, wakeup) owns p->pi_lock, ->cpus_allowed is stable.
*/
static inline
int select_task_rq(struct task_struct *p, int sd_flags, int wake_flags)
{
int cpu = p->sched_class->select_task_rq(p, sd_flags, wake_flags);
/*
* In order not to call set_task_cpu() on a blocking task we need
* to rely on ttwu() to place the task on a valid ->cpus_allowed
* cpu.
*
* Since this is common to all placement strategies, this lives here.
*
* [ this allows ->select_task() to simply return task_cpu(p) and
* not worry about this generic constraint ]
*/
if (unlikely(!cpumask_test_cpu(cpu, &p->cpus_allowed) ||
!cpu_online(cpu)))
cpu = select_fallback_rq(task_cpu(p), p);
return cpu;
}
static void update_avg(u64 *avg, u64 sample)
{
s64 diff = sample - *avg;
*avg += diff >> 3;
}
#endif
static void
ttwu_stat(struct task_struct *p, int cpu, int wake_flags)
{
#ifdef CONFIG_SCHEDSTATS
struct rq *rq = this_rq();
#ifdef CONFIG_SMP
int this_cpu = smp_processor_id();
if (cpu == this_cpu) {
schedstat_inc(rq, ttwu_local);
schedstat_inc(p, se.statistics.nr_wakeups_local);
} else {
struct sched_domain *sd;
schedstat_inc(p, se.statistics.nr_wakeups_remote);
rcu_read_lock();
for_each_domain(this_cpu, sd) {
if (cpumask_test_cpu(cpu, sched_domain_span(sd))) {
schedstat_inc(sd, ttwu_wake_remote);
break;
}
}
rcu_read_unlock();
}
if (wake_flags & WF_MIGRATED)
schedstat_inc(p, se.statistics.nr_wakeups_migrate);
#endif /* CONFIG_SMP */
schedstat_inc(rq, ttwu_count);
schedstat_inc(p, se.statistics.nr_wakeups);
if (wake_flags & WF_SYNC)
schedstat_inc(p, se.statistics.nr_wakeups_sync);
#endif /* CONFIG_SCHEDSTATS */
}
static void ttwu_activate(struct rq *rq, struct task_struct *p, int en_flags)
{
activate_task(rq, p, en_flags);
p->on_rq = 1;
/* if a worker is waking up, notify workqueue */
if (p->flags & PF_WQ_WORKER)
wq_worker_waking_up(p, cpu_of(rq));
}
/*
* Mark the task runnable and perform wakeup-preemption.
*/
static void
ttwu_do_wakeup(struct rq *rq, struct task_struct *p, int wake_flags)
{
trace_sched_wakeup(p, true);
check_preempt_curr(rq, p, wake_flags);
p->state = TASK_RUNNING;
#ifdef CONFIG_SMP
if (p->sched_class->task_woken)
p->sched_class->task_woken(rq, p);
if (rq->idle_stamp) {
u64 delta = rq->clock - rq->idle_stamp;
u64 max = 2*sysctl_sched_migration_cost;
if (delta > max)
rq->avg_idle = max;
else
update_avg(&rq->avg_idle, delta);
rq->idle_stamp = 0;
}
#endif
}
static void
ttwu_do_activate(struct rq *rq, struct task_struct *p, int wake_flags)
{
#ifdef CONFIG_SMP
if (p->sched_contributes_to_load)
rq->nr_uninterruptible--;
#endif
ttwu_activate(rq, p, ENQUEUE_WAKEUP | ENQUEUE_WAKING);
ttwu_do_wakeup(rq, p, wake_flags);
}
/*
* Called in case the task @p isn't fully descheduled from its runqueue,
* in this case we must do a remote wakeup. Its a 'light' wakeup though,
* since all we need to do is flip p->state to TASK_RUNNING, since
* the task is still ->on_rq.
*/
static int ttwu_remote(struct task_struct *p, int wake_flags)
{
struct rq *rq;
int ret = 0;
rq = __task_rq_lock(p);
if (p->on_rq) {
ttwu_do_wakeup(rq, p, wake_flags);
ret = 1;
}
__task_rq_unlock(rq);
return ret;
}
#ifdef CONFIG_SMP
static void sched_ttwu_do_pending(struct task_struct *list)
{
struct rq *rq = this_rq();
raw_spin_lock(&rq->lock);
while (list) {
struct task_struct *p = list;
list = list->wake_entry;
ttwu_do_activate(rq, p, 0);
}
raw_spin_unlock(&rq->lock);
}
#ifdef CONFIG_HOTPLUG_CPU
static void sched_ttwu_pending(void)
{
struct rq *rq = this_rq();
struct task_struct *list = xchg(&rq->wake_list, NULL);
if (!list)
return;
sched_ttwu_do_pending(list);
}
#endif /* CONFIG_HOTPLUG_CPU */
void scheduler_ipi(void)
{
struct rq *rq = this_rq();
struct task_struct *list = xchg(&rq->wake_list, NULL);
if (!list)
return;
/*
* Not all reschedule IPI handlers call irq_enter/irq_exit, since
* traditionally all their work was done from the interrupt return
* path. Now that we actually do some work, we need to make sure
* we do call them.
*
* Some archs already do call them, luckily irq_enter/exit nest
* properly.
*
* Arguably we should visit all archs and update all handlers,
* however a fair share of IPIs are still resched only so this would
* somewhat pessimize the simple resched case.
*/
irq_enter();
sched_ttwu_do_pending(list);
irq_exit();
}
static void ttwu_queue_remote(struct task_struct *p, int cpu)
{
struct rq *rq = cpu_rq(cpu);
struct task_struct *next = rq->wake_list;
for (;;) {
struct task_struct *old = next;
p->wake_entry = next;
next = cmpxchg(&rq->wake_list, old, p);
if (next == old)
break;
}
if (!next)
smp_send_reschedule(cpu);
}
#ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW
static int ttwu_activate_remote(struct task_struct *p, int wake_flags)
{
struct rq *rq;
int ret = 0;
rq = __task_rq_lock(p);
if (p->on_cpu) {
ttwu_activate(rq, p, ENQUEUE_WAKEUP);
ttwu_do_wakeup(rq, p, wake_flags);
ret = 1;
}
__task_rq_unlock(rq);
return ret;
}
#endif /* __ARCH_WANT_INTERRUPTS_ON_CTXSW */
#endif /* CONFIG_SMP */
static void ttwu_queue(struct task_struct *p, int cpu)
{
struct rq *rq = cpu_rq(cpu);
#if defined(CONFIG_SMP)
if (sched_feat(TTWU_QUEUE) && cpu != smp_processor_id()) {
sched_clock_cpu(cpu); /* sync clocks x-cpu */
ttwu_queue_remote(p, cpu);
return;
}
#endif
raw_spin_lock(&rq->lock);
ttwu_do_activate(rq, p, 0);
raw_spin_unlock(&rq->lock);
}
/**
* try_to_wake_up - wake up a thread
* @p: the thread to be awakened
* @state: the mask of task states that can be woken
* @wake_flags: wake modifier flags (WF_*)
*
* Put it on the run-queue if it's not already there. The "current"
* thread is always on the run-queue (except when the actual
* re-schedule is in progress), and as such you're allowed to do
* the simpler "current->state = TASK_RUNNING" to mark yourself
* runnable without the overhead of this.
*
* Returns %true if @p was woken up, %false if it was already running
* or @state didn't match @p's state.
*/
static int
try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags)
{
unsigned long flags;
int cpu, success = 0;
smp_wmb();
raw_spin_lock_irqsave(&p->pi_lock, flags);
if (!(p->state & state))
goto out;
success = 1; /* we're going to change ->state */
cpu = task_cpu(p);
if (p->on_rq && ttwu_remote(p, wake_flags))
goto stat;
#ifdef CONFIG_SMP
/*
* If the owning (remote) cpu is still in the middle of schedule() with
* this task as prev, wait until its done referencing the task.
*/
while (p->on_cpu) {
#ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW
/*
* In case the architecture enables interrupts in
* context_switch(), we cannot busy wait, since that
* would lead to deadlocks when an interrupt hits and
* tries to wake up @prev. So bail and do a complete
* remote wakeup.
*/
if (ttwu_activate_remote(p, wake_flags))
goto stat;
#else
cpu_relax();
#endif
}
/*
* Pairs with the smp_wmb() in finish_lock_switch().
*/
smp_rmb();
p->sched_contributes_to_load = !!task_contributes_to_load(p);
p->state = TASK_WAKING;
if (p->sched_class->task_waking)
p->sched_class->task_waking(p);
cpu = select_task_rq(p, SD_BALANCE_WAKE, wake_flags);
if (task_cpu(p) != cpu) {
wake_flags |= WF_MIGRATED;
set_task_cpu(p, cpu);
}
#endif /* CONFIG_SMP */
ttwu_queue(p, cpu);
stat:
ttwu_stat(p, cpu, wake_flags);
out:
raw_spin_unlock_irqrestore(&p->pi_lock, flags);
return success;
}
/**
* try_to_wake_up_local - try to wake up a local task with rq lock held
* @p: the thread to be awakened
*
* Put @p on the run-queue if it's not already there. The caller must
* ensure that this_rq() is locked, @p is bound to this_rq() and not
* the current task.
*/
static void try_to_wake_up_local(struct task_struct *p)
{
struct rq *rq = task_rq(p);
BUG_ON(rq != this_rq());
BUG_ON(p == current);
lockdep_assert_held(&rq->lock);
if (!raw_spin_trylock(&p->pi_lock)) {
raw_spin_unlock(&rq->lock);
raw_spin_lock(&p->pi_lock);
raw_spin_lock(&rq->lock);
}
if (!(p->state & TASK_NORMAL))
goto out;
if (!p->on_rq)
ttwu_activate(rq, p, ENQUEUE_WAKEUP);
ttwu_do_wakeup(rq, p, 0);
ttwu_stat(p, smp_processor_id(), 0);
out:
raw_spin_unlock(&p->pi_lock);
}
/**
* wake_up_process - Wake up a specific process
* @p: The process to be woken up.
*
* Attempt to wake up the nominated process and move it to the set of runnable
* processes. Returns 1 if the process was woken up, 0 if it was already
* running.
*
* It may be assumed that this function implies a write memory barrier before
* changing the task state if and only if any tasks are woken up.
*/
int wake_up_process(struct task_struct *p)
{
return try_to_wake_up(p, TASK_ALL, 0);
}
EXPORT_SYMBOL(wake_up_process);
int wake_up_state(struct task_struct *p, unsigned int state)
{
return try_to_wake_up(p, state, 0);
}
/*
* Perform scheduler related setup for a newly forked process p.
* p is forked by current.
*
* __sched_fork() is basic setup used by init_idle() too:
*/
static void __sched_fork(struct task_struct *p)
{
p->on_rq = 0;
p->se.on_rq = 0;
p->se.exec_start = 0;
p->se.sum_exec_runtime = 0;
p->se.prev_sum_exec_runtime = 0;
p->se.nr_migrations = 0;
p->se.vruntime = 0;
INIT_LIST_HEAD(&p->se.group_node);
#ifdef CONFIG_SCHEDSTATS
memset(&p->se.statistics, 0, sizeof(p->se.statistics));
#endif
INIT_LIST_HEAD(&p->rt.run_list);
#ifdef CONFIG_PREEMPT_NOTIFIERS
INIT_HLIST_HEAD(&p->preempt_notifiers);
#endif
}
/*
* fork()/clone()-time setup:
*/
void sched_fork(struct task_struct *p)
{
unsigned long flags;
int cpu = get_cpu();
__sched_fork(p);
/*
* We mark the process as running here. This guarantees that
* nobody will actually run it, and a signal or other external
* event cannot wake it up and insert it on the runqueue either.
*/
p->state = TASK_RUNNING;
/*
* Revert to default priority/policy on fork if requested.
*/
if (unlikely(p->sched_reset_on_fork)) {
if (p->policy == SCHED_FIFO || p->policy == SCHED_RR) {
p->policy = SCHED_NORMAL;
p->normal_prio = p->static_prio;
}
if (PRIO_TO_NICE(p->static_prio) < 0) {
p->static_prio = NICE_TO_PRIO(0);
p->normal_prio = p->static_prio;
set_load_weight(p);
}
/*
* We don't need the reset flag anymore after the fork. It has
* fulfilled its duty:
*/
p->sched_reset_on_fork = 0;
}
/*
* Make sure we do not leak PI boosting priority to the child.
*/
p->prio = current->normal_prio;
if (!rt_prio(p->prio))
p->sched_class = &fair_sched_class;
if (p->sched_class->task_fork)
p->sched_class->task_fork(p);
/*
* The child is not yet in the pid-hash so no cgroup attach races,
* and the cgroup is pinned to this child due to cgroup_fork()
* is ran before sched_fork().
*
* Silence PROVE_RCU.
*/
raw_spin_lock_irqsave(&p->pi_lock, flags);
set_task_cpu(p, cpu);
raw_spin_unlock_irqrestore(&p->pi_lock, flags);
#if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT)
if (likely(sched_info_on()))
memset(&p->sched_info, 0, sizeof(p->sched_info));
#endif
#if defined(CONFIG_SMP)
p->on_cpu = 0;
#endif
#ifdef CONFIG_PREEMPT_COUNT
/* Want to start with kernel preemption disabled. */
task_thread_info(p)->preempt_count = 1;
#endif
#ifdef CONFIG_SMP
plist_node_init(&p->pushable_tasks, MAX_PRIO);
#endif
put_cpu();
}
/*
* wake_up_new_task - wake up a newly created task for the first time.
*
* This function will do some initial scheduler statistics housekeeping
* that must be done for every newly created context, then puts the task
* on the runqueue and wakes it.
*/
void wake_up_new_task(struct task_struct *p)
{
unsigned long flags;
struct rq *rq;
raw_spin_lock_irqsave(&p->pi_lock, flags);
#ifdef CONFIG_SMP
/*
* Fork balancing, do it here and not earlier because:
* - cpus_allowed can change in the fork path
* - any previously selected cpu might disappear through hotplug
*/
set_task_cpu(p, select_task_rq(p, SD_BALANCE_FORK, 0));
#endif
rq = __task_rq_lock(p);
activate_task(rq, p, 0);
p->on_rq = 1;
trace_sched_wakeup_new(p, true);
check_preempt_curr(rq, p, WF_FORK);
#ifdef CONFIG_SMP
if (p->sched_class->task_woken)
p->sched_class->task_woken(rq, p);
#endif
task_rq_unlock(rq, p, &flags);
}
#ifdef CONFIG_PREEMPT_NOTIFIERS
/**
* preempt_notifier_register - tell me when current is being preempted & rescheduled
* @notifier: notifier struct to register
*/
void preempt_notifier_register(struct preempt_notifier *notifier)
{
hlist_add_head(&notifier->link, &current->preempt_notifiers);
}
EXPORT_SYMBOL_GPL(preempt_notifier_register);
/**
* preempt_notifier_unregister - no longer interested in preemption notifications
* @notifier: notifier struct to unregister
*
* This is safe to call from within a preemption notifier.
*/
void preempt_notifier_unregister(struct preempt_notifier *notifier)
{
hlist_del(&notifier->link);
}
EXPORT_SYMBOL_GPL(preempt_notifier_unregister);
static void fire_sched_in_preempt_notifiers(struct task_struct *curr)
{
struct preempt_notifier *notifier;
struct hlist_node *node;
hlist_for_each_entry(notifier, node, &curr->preempt_notifiers, link)
notifier->ops->sched_in(notifier, raw_smp_processor_id());
}
static void
fire_sched_out_preempt_notifiers(struct task_struct *curr,
struct task_struct *next)
{
struct preempt_notifier *notifier;
struct hlist_node *node;
hlist_for_each_entry(notifier, node, &curr->preempt_notifiers, link)
notifier->ops->sched_out(notifier, next);
}
#else /* !CONFIG_PREEMPT_NOTIFIERS */
static void fire_sched_in_preempt_notifiers(struct task_struct *curr)
{
}
static void
fire_sched_out_preempt_notifiers(struct task_struct *curr,
struct task_struct *next)
{
}
#endif /* CONFIG_PREEMPT_NOTIFIERS */
/**
* prepare_task_switch - prepare to switch tasks
* @rq: the runqueue preparing to switch
* @prev: the current task that is being switched out
* @next: the task we are going to switch to.
*
* This is called with the rq lock held and interrupts off. It must
* be paired with a subsequent finish_task_switch after the context
* switch.
*
* prepare_task_switch sets up locking and calls architecture specific
* hooks.
*/
static inline void
prepare_task_switch(struct rq *rq, struct task_struct *prev,
struct task_struct *next)
{
sched_info_switch(prev, next);
perf_event_task_sched_out(prev, next);
fire_sched_out_preempt_notifiers(prev, next);
prepare_lock_switch(rq, next);
prepare_arch_switch(next);
trace_sched_switch(prev, next);
}
/**
* finish_task_switch - clean up after a task-switch
* @rq: runqueue associated with task-switch
* @prev: the thread we just switched away from.
*
* finish_task_switch must be called after the context switch, paired
* with a prepare_task_switch call before the context switch.
* finish_task_switch will reconcile locking set up by prepare_task_switch,
* and do any other architecture-specific cleanup actions.
*
* Note that we may have delayed dropping an mm in context_switch(). If
* so, we finish that here outside of the runqueue lock. (Doing it
* with the lock held can cause deadlocks; see schedule() for
* details.)
*/
static void finish_task_switch(struct rq *rq, struct task_struct *prev)
__releases(rq->lock)
{
struct mm_struct *mm = rq->prev_mm;
long prev_state;
rq->prev_mm = NULL;
/*
* A task struct has one reference for the use as "current".
* If a task dies, then it sets TASK_DEAD in tsk->state and calls
* schedule one last time. The schedule call will never return, and
* the scheduled task must drop that reference.
* The test for TASK_DEAD must occur while the runqueue locks are
* still held, otherwise prev could be scheduled on another cpu, die
* there before we look at prev->state, and then the reference would
* be dropped twice.
* Manfred Spraul <manfred@colorfullife.com>
*/
prev_state = prev->state;
finish_arch_switch(prev);
#ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW
local_irq_disable();
#endif /* __ARCH_WANT_INTERRUPTS_ON_CTXSW */
perf_event_task_sched_in(current);
#ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW
local_irq_enable();
#endif /* __ARCH_WANT_INTERRUPTS_ON_CTXSW */
finish_lock_switch(rq, prev);
fire_sched_in_preempt_notifiers(current);
if (mm)
mmdrop(mm);
if (unlikely(prev_state == TASK_DEAD)) {
/*
* Remove function-return probe instances associated with this
* task and put them back on the free list.
*/
kprobe_flush_task(prev);
put_task_struct(prev);
}
}
#ifdef CONFIG_SMP
/* assumes rq->lock is held */
static inline void pre_schedule(struct rq *rq, struct task_struct *prev)
{
if (prev->sched_class->pre_schedule)
prev->sched_class->pre_schedule(rq, prev);
}
/* rq->lock is NOT held, but preemption is disabled */
static inline void post_schedule(struct rq *rq)
{
if (rq->post_schedule) {
unsigned long flags;
raw_spin_lock_irqsave(&rq->lock, flags);
if (rq->curr->sched_class->post_schedule)
rq->curr->sched_class->post_schedule(rq);
raw_spin_unlock_irqrestore(&rq->lock, flags);
rq->post_schedule = 0;
}
}
#else
static inline void pre_schedule(struct rq *rq, struct task_struct *p)
{
}
static inline void post_schedule(struct rq *rq)
{
}
#endif
/**
* schedule_tail - first thing a freshly forked thread must call.
* @prev: the thread we just switched away from.
*/
asmlinkage void schedule_tail(struct task_struct *prev)
__releases(rq->lock)
{
struct rq *rq = this_rq();
finish_task_switch(rq, prev);
/*
* FIXME: do we need to worry about rq being invalidated by the
* task_switch?
*/
post_schedule(rq);
#ifdef __ARCH_WANT_UNLOCKED_CTXSW
/* In this case, finish_task_switch does not reenable preemption */
preempt_enable();
#endif
if (current->set_child_tid)
put_user(task_pid_vnr(current), current->set_child_tid);
}
/*
* context_switch - switch to the new MM and the new
* thread's register state.
*/
static inline void
context_switch(struct rq *rq, struct task_struct *prev,
struct task_struct *next)
{
struct mm_struct *mm, *oldmm;
prepare_task_switch(rq, prev, next);
mm = next->mm;
oldmm = prev->active_mm;
/*
* For paravirt, this is coupled with an exit in switch_to to
* combine the page table reload and the switch backend into
* one hypercall.
*/
arch_start_context_switch(prev);
if (!mm) {
next->active_mm = oldmm;
atomic_inc(&oldmm->mm_count);
enter_lazy_tlb(oldmm, next);
} else
switch_mm(oldmm, mm, next);
if (!prev->mm) {
prev->active_mm = NULL;
rq->prev_mm = oldmm;
}
/*
* Since the runqueue lock will be released by the next
* task (which is an invalid locking op but in the case
* of the scheduler it's an obvious special-case), so we
* do an early lockdep release here:
*/
#ifndef __ARCH_WANT_UNLOCKED_CTXSW
spin_release(&rq->lock.dep_map, 1, _THIS_IP_);
#endif
/* Here we just switch the register state and the stack. */
switch_to(prev, next, prev);
barrier();
/*
* this_rq must be evaluated again because prev may have moved
* CPUs since it called schedule(), thus the 'rq' on its stack
* frame will be invalid.
*/
finish_task_switch(this_rq(), prev);
}
/*
* nr_running, nr_uninterruptible and nr_context_switches:
*
* externally visible scheduler statistics: current number of runnable
* threads, current number of uninterruptible-sleeping threads, total
* number of context switches performed since bootup.
*/
unsigned long nr_running(void)
{
unsigned long i, sum = 0;
for_each_online_cpu(i)
sum += cpu_rq(i)->nr_running;
return sum;
}
unsigned long nr_uninterruptible(void)
{
unsigned long i, sum = 0;
for_each_possible_cpu(i)
sum += cpu_rq(i)->nr_uninterruptible;
/*
* Since we read the counters lockless, it might be slightly
* inaccurate. Do not allow it to go below zero though:
*/
if (unlikely((long)sum < 0))
sum = 0;
return sum;
}
unsigned long long nr_context_switches(void)
{
int i;
unsigned long long sum = 0;
for_each_possible_cpu(i)
sum += cpu_rq(i)->nr_switches;
return sum;
}
unsigned long nr_iowait(void)
{
unsigned long i, sum = 0;
for_each_possible_cpu(i)
sum += atomic_read(&cpu_rq(i)->nr_iowait);
return sum;
}
unsigned long nr_iowait_cpu(int cpu)
{
struct rq *this = cpu_rq(cpu);
return atomic_read(&this->nr_iowait);
}
unsigned long this_cpu_load(void)
{
struct rq *this = this_rq();
return this->cpu_load[0];
}
/* Variables and functions for calc_load */
static atomic_long_t calc_load_tasks;
static unsigned long calc_load_update;
unsigned long avenrun[3];
EXPORT_SYMBOL(avenrun);
static long calc_load_fold_active(struct rq *this_rq)
{
long nr_active, delta = 0;
nr_active = this_rq->nr_running;
nr_active += (long) this_rq->nr_uninterruptible;
if (nr_active != this_rq->calc_load_active) {
delta = nr_active - this_rq->calc_load_active;
this_rq->calc_load_active = nr_active;
}
return delta;
}
static unsigned long
calc_load(unsigned long load, unsigned long exp, unsigned long active)
{
load *= exp;
load += active * (FIXED_1 - exp);
load += 1UL << (FSHIFT - 1);
return load >> FSHIFT;
}
#ifdef CONFIG_NO_HZ
/*
* For NO_HZ we delay the active fold to the next LOAD_FREQ update.
*
* When making the ILB scale, we should try to pull this in as well.
*/
static atomic_long_t calc_load_tasks_idle;
static void calc_load_account_idle(struct rq *this_rq)
{
long delta;
delta = calc_load_fold_active(this_rq);
if (delta)
atomic_long_add(delta, &calc_load_tasks_idle);
}
static long calc_load_fold_idle(void)
{
long delta = 0;
/*
* Its got a race, we don't care...
*/
if (atomic_long_read(&calc_load_tasks_idle))
delta = atomic_long_xchg(&calc_load_tasks_idle, 0);
return delta;
}
/**
* fixed_power_int - compute: x^n, in O(log n) time
*
* @x: base of the power
* @frac_bits: fractional bits of @x
* @n: power to raise @x to.
*
* By exploiting the relation between the definition of the natural power
* function: x^n := x*x*...*x (x multiplied by itself for n times), and
* the binary encoding of numbers used by computers: n := \Sum n_i * 2^i,
* (where: n_i \elem {0, 1}, the binary vector representing n),
* we find: x^n := x^(\Sum n_i * 2^i) := \Prod x^(n_i * 2^i), which is
* of course trivially computable in O(log_2 n), the length of our binary
* vector.
*/
static unsigned long
fixed_power_int(unsigned long x, unsigned int frac_bits, unsigned int n)
{
unsigned long result = 1UL << frac_bits;
if (n) for (;;) {
if (n & 1) {
result *= x;
result += 1UL << (frac_bits - 1);
result >>= frac_bits;
}
n >>= 1;
if (!n)
break;
x *= x;
x += 1UL << (frac_bits - 1);
x >>= frac_bits;
}
return result;
}
/*
* a1 = a0 * e + a * (1 - e)
*
* a2 = a1 * e + a * (1 - e)
* = (a0 * e + a * (1 - e)) * e + a * (1 - e)
* = a0 * e^2 + a * (1 - e) * (1 + e)
*
* a3 = a2 * e + a * (1 - e)
* = (a0 * e^2 + a * (1 - e) * (1 + e)) * e + a * (1 - e)
* = a0 * e^3 + a * (1 - e) * (1 + e + e^2)
*
* ...
*
* an = a0 * e^n + a * (1 - e) * (1 + e + ... + e^n-1) [1]
* = a0 * e^n + a * (1 - e) * (1 - e^n)/(1 - e)
* = a0 * e^n + a * (1 - e^n)
*
* [1] application of the geometric series:
*
* n 1 - x^(n+1)
* S_n := \Sum x^i = -------------
* i=0 1 - x
*/
static unsigned long
calc_load_n(unsigned long load, unsigned long exp,
unsigned long active, unsigned int n)
{
return calc_load(load, fixed_power_int(exp, FSHIFT, n), active);
}
/*
* NO_HZ can leave us missing all per-cpu ticks calling
* calc_load_account_active(), but since an idle CPU folds its delta into
* calc_load_tasks_idle per calc_load_account_idle(), all we need to do is fold
* in the pending idle delta if our idle period crossed a load cycle boundary.
*
* Once we've updated the global active value, we need to apply the exponential
* weights adjusted to the number of cycles missed.
*/
static void calc_global_nohz(unsigned long ticks)
{
long delta, active, n;
if (time_before(jiffies, calc_load_update))
return;
/*
* If we crossed a calc_load_update boundary, make sure to fold
* any pending idle changes, the respective CPUs might have
* missed the tick driven calc_load_account_active() update
* due to NO_HZ.
*/
delta = calc_load_fold_idle();
if (delta)
atomic_long_add(delta, &calc_load_tasks);
/*
* If we were idle for multiple load cycles, apply them.
*/
if (ticks >= LOAD_FREQ) {
n = ticks / LOAD_FREQ;
active = atomic_long_read(&calc_load_tasks);
active = active > 0 ? active * FIXED_1 : 0;
avenrun[0] = calc_load_n(avenrun[0], EXP_1, active, n);
avenrun[1] = calc_load_n(avenrun[1], EXP_5, active, n);
avenrun[2] = calc_load_n(avenrun[2], EXP_15, active, n);
calc_load_update += n * LOAD_FREQ;
}
/*
* Its possible the remainder of the above division also crosses
* a LOAD_FREQ period, the regular check in calc_global_load()
* which comes after this will take care of that.
*
* Consider us being 11 ticks before a cycle completion, and us
* sleeping for 4*LOAD_FREQ + 22 ticks, then the above code will
* age us 4 cycles, and the test in calc_global_load() will
* pick up the final one.
*/
}
#else
static void calc_load_account_idle(struct rq *this_rq)
{
}
static inline long calc_load_fold_idle(void)
{
return 0;
}
static void calc_global_nohz(unsigned long ticks)
{
}
#endif
/**
* get_avenrun - get the load average array
* @loads: pointer to dest load array
* @offset: offset to add
* @shift: shift count to shift the result left
*
* These values are estimates at best, so no need for locking.
*/
void get_avenrun(unsigned long *loads, unsigned long offset, int shift)
{
loads[0] = (avenrun[0] + offset) << shift;
loads[1] = (avenrun[1] + offset) << shift;
loads[2] = (avenrun[2] + offset) << shift;
}
/*
* calc_load - update the avenrun load estimates 10 ticks after the
* CPUs have updated calc_load_tasks.
*/
void calc_global_load(unsigned long ticks)
{
long active;
calc_global_nohz(ticks);
if (time_before(jiffies, calc_load_update + 10))
return;
active = atomic_long_read(&calc_load_tasks);
active = active > 0 ? active * FIXED_1 : 0;
avenrun[0] = calc_load(avenrun[0], EXP_1, active);
avenrun[1] = calc_load(avenrun[1], EXP_5, active);
avenrun[2] = calc_load(avenrun[2], EXP_15, active);
calc_load_update += LOAD_FREQ;
}
/*
* Called from update_cpu_load() to periodically update this CPU's
* active count.
*/
static void calc_load_account_active(struct rq *this_rq)
{
long delta;
if (time_before(jiffies, this_rq->calc_load_update))
return;
delta = calc_load_fold_active(this_rq);
delta += calc_load_fold_idle();
if (delta)
atomic_long_add(delta, &calc_load_tasks);
this_rq->calc_load_update += LOAD_FREQ;
}
/*
* The exact cpuload at various idx values, calculated at every tick would be
* load = (2^idx - 1) / 2^idx * load + 1 / 2^idx * cur_load
*
* If a cpu misses updates for n-1 ticks (as it was idle) and update gets called
* on nth tick when cpu may be busy, then we have:
* load = ((2^idx - 1) / 2^idx)^(n-1) * load
* load = (2^idx - 1) / 2^idx) * load + 1 / 2^idx * cur_load
*
* decay_load_missed() below does efficient calculation of
* load = ((2^idx - 1) / 2^idx)^(n-1) * load
* avoiding 0..n-1 loop doing load = ((2^idx - 1) / 2^idx) * load
*
* The calculation is approximated on a 128 point scale.
* degrade_zero_ticks is the number of ticks after which load at any
* particular idx is approximated to be zero.
* degrade_factor is a precomputed table, a row for each load idx.
* Each column corresponds to degradation factor for a power of two ticks,
* based on 128 point scale.
* Example:
* row 2, col 3 (=12) says that the degradation at load idx 2 after
* 8 ticks is 12/128 (which is an approximation of exact factor 3^8/4^8).
*
* With this power of 2 load factors, we can degrade the load n times
* by looking at 1 bits in n and doing as many mult/shift instead of
* n mult/shifts needed by the exact degradation.
*/
#define DEGRADE_SHIFT 7
static const unsigned char
degrade_zero_ticks[CPU_LOAD_IDX_MAX] = {0, 8, 32, 64, 128};
static const unsigned char
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},
{112, 98, 75, 43, 15, 1, 0},
{120, 112, 98, 76, 45, 16, 2} };
/*
* 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;
}
/*
* Update rq->cpu_load[] statistics. This function is usually called every
* scheduler tick (TICK_NSEC). With tickless idle this will not be called
* every tick. We fix it up based on jiffies.
*/
static void update_cpu_load(struct rq *this_rq)
{
unsigned long this_load = this_rq->load.weight;
unsigned long curr_jiffies = jiffies;
unsigned long pending_updates;
int i, scale;
this_rq->nr_load_updates++;
/* Avoid repeated calls on same jiffy, when moving in and out of idle */
if (curr_jiffies == this_rq->last_load_update_tick)
return;
pending_updates = curr_jiffies - this_rq->last_load_update_tick;
this_rq->last_load_update_tick = curr_jiffies;
/* 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];
old_load = decay_load_missed(old_load, pending_updates - 1, i);
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);
}
static void update_cpu_load_active(struct rq *this_rq)
{
update_cpu_load(this_rq);
calc_load_account_active(this_rq);
}
#ifdef CONFIG_SMP
/*
* sched_exec - execve() is a valuable balancing opportunity, because at
* this point the task has the smallest effective memory and cache footprint.
*/
void sched_exec(void)
{
struct task_struct *p = current;
unsigned long flags;
int dest_cpu;
raw_spin_lock_irqsave(&p->pi_lock, flags);
dest_cpu = p->sched_class->select_task_rq(p, SD_BALANCE_EXEC, 0);
if (dest_cpu == smp_processor_id())
goto unlock;
if (likely(cpu_active(dest_cpu))) {
struct migration_arg arg = { p, dest_cpu };
raw_spin_unlock_irqrestore(&p->pi_lock, flags);
stop_one_cpu(task_cpu(p), migration_cpu_stop, &arg);
return;
}
unlock:
raw_spin_unlock_irqrestore(&p->pi_lock, flags);
}
#endif
DEFINE_PER_CPU(struct kernel_stat, kstat);
EXPORT_PER_CPU_SYMBOL(kstat);
/*
* Return any ns on the sched_clock that have not yet been accounted in
* @p in case that task is currently running.
*
* Called with task_rq_lock() held on @rq.
*/
static u64 do_task_delta_exec(struct task_struct *p, struct rq *rq)
{
u64 ns = 0;
if (task_current(rq, p)) {
update_rq_clock(rq);
ns = rq->clock_task - p->se.exec_start;
if ((s64)ns < 0)
ns = 0;
}
return ns;
}
unsigned long long task_delta_exec(struct task_struct *p)
{
unsigned long flags;
struct rq *rq;
u64 ns = 0;
rq = task_rq_lock(p, &flags);
ns = do_task_delta_exec(p, rq);
task_rq_unlock(rq, p, &flags);
return ns;
}
/*
* Return accounted runtime for the task.
* In case the task is currently running, return the runtime plus current's
* pending runtime that have not been accounted yet.
*/
unsigned long long task_sched_runtime(struct task_struct *p)
{
unsigned long flags;
struct rq *rq;
u64 ns = 0;
rq = task_rq_lock(p, &flags);
ns = p->se.sum_exec_runtime + do_task_delta_exec(p, rq);
task_rq_unlock(rq, p, &flags);
return ns;
}
/*
* Return sum_exec_runtime for the thread group.
* In case the task is currently running, return the sum plus current's
* pending runtime that have not been accounted yet.
*
* Note that the thread group might have other running tasks as well,
* so the return value not includes other pending runtime that other
* running tasks might have.
*/
unsigned long long thread_group_sched_runtime(struct task_struct *p)
{
struct task_cputime totals;
unsigned long flags;
struct rq *rq;
u64 ns;
rq = task_rq_lock(p, &flags);
thread_group_cputime(p, &totals);
ns = totals.sum_exec_runtime + do_task_delta_exec(p, rq);
task_rq_unlock(rq, p, &flags);
return ns;
}
/*
* Account user cpu time to a process.
* @p: the process that the cpu time gets accounted to
* @cputime: the cpu time spent in user space since the last update
* @cputime_scaled: cputime scaled by cpu frequency
*/
void account_user_time(struct task_struct *p, cputime_t cputime,
cputime_t cputime_scaled)
{
struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat;
cputime64_t tmp;
/* Add user time to process. */
p->utime = cputime_add(p->utime, cputime);
p->utimescaled = cputime_add(p->utimescaled, cputime_scaled);
account_group_user_time(p, cputime);
/* Add user time to cpustat. */
tmp = cputime_to_cputime64(cputime);
if (TASK_NICE(p) > 0)
cpustat->nice = cputime64_add(cpustat->nice, tmp);
else
cpustat->user = cputime64_add(cpustat->user, tmp);
cpuacct_update_stats(p, CPUACCT_STAT_USER, cputime);
/* Account for user time used */
acct_update_integrals(p);
}
/*
* Account guest cpu time to a process.
* @p: the process that the cpu time gets accounted to
* @cputime: the cpu time spent in virtual machine since the last update
* @cputime_scaled: cputime scaled by cpu frequency
*/
static void account_guest_time(struct task_struct *p, cputime_t cputime,
cputime_t cputime_scaled)
{
cputime64_t tmp;
struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat;
tmp = cputime_to_cputime64(cputime);
/* Add guest time to process. */
p->utime = cputime_add(p->utime, cputime);
p->utimescaled = cputime_add(p->utimescaled, cputime_scaled);
account_group_user_time(p, cputime);
p->gtime = cputime_add(p->gtime, cputime);
/* Add guest time to cpustat. */
if (TASK_NICE(p) > 0) {
cpustat->nice = cputime64_add(cpustat->nice, tmp);
cpustat->guest_nice = cputime64_add(cpustat->guest_nice, tmp);
} else {
cpustat->user = cputime64_add(cpustat->user, tmp);
cpustat->guest = cputime64_add(cpustat->guest, tmp);
}
}
/*
* Account system cpu time to a process and desired cpustat field
* @p: the process that the cpu time gets accounted to
* @cputime: the cpu time spent in kernel space since the last update
* @cputime_scaled: cputime scaled by cpu frequency
* @target_cputime64: pointer to cpustat field that has to be updated
*/
static inline
void __account_system_time(struct task_struct *p, cputime_t cputime,
cputime_t cputime_scaled, cputime64_t *target_cputime64)
{
cputime64_t tmp = cputime_to_cputime64(cputime);
/* Add system time to process. */
p->stime = cputime_add(p->stime, cputime);
p->stimescaled = cputime_add(p->stimescaled, cputime_scaled);
account_group_system_time(p, cputime);
/* Add system time to cpustat. */
*target_cputime64 = cputime64_add(*target_cputime64, tmp);
cpuacct_update_stats(p, CPUACCT_STAT_SYSTEM, cputime);
/* Account for system time used */
acct_update_integrals(p);
}
/*
* Account system cpu time to a process.
* @p: the process that the cpu time gets accounted to
* @hardirq_offset: the offset to subtract from hardirq_count()
* @cputime: the cpu time spent in kernel space since the last update
* @cputime_scaled: cputime scaled by cpu frequency
*/
void account_system_time(struct task_struct *p, int hardirq_offset,
cputime_t cputime, cputime_t cputime_scaled)
{
struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat;
cputime64_t *target_cputime64;
if ((p->flags & PF_VCPU) && (irq_count() - hardirq_offset == 0)) {
account_guest_time(p, cputime, cputime_scaled);
return;
}
if (hardirq_count() - hardirq_offset)
target_cputime64 = &cpustat->irq;
else if (in_serving_softirq())
target_cputime64 = &cpustat->softirq;
else
target_cputime64 = &cpustat->system;
__account_system_time(p, cputime, cputime_scaled, target_cputime64);
}
/*
* Account for involuntary wait time.
* @cputime: the cpu time spent in involuntary wait
*/
void account_steal_time(cputime_t cputime)
{
struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat;
cputime64_t cputime64 = cputime_to_cputime64(cputime);
cpustat->steal = cputime64_add(cpustat->steal, cputime64);
}
/*
* Account for idle time.
* @cputime: the cpu time spent in idle wait
*/
void account_idle_time(cputime_t cputime)
{
struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat;
cputime64_t cputime64 = cputime_to_cputime64(cputime);
struct rq *rq = this_rq();
if (atomic_read(&rq->nr_iowait) > 0)
cpustat->iowait = cputime64_add(cpustat->iowait, cputime64);
else
cpustat->idle = cputime64_add(cpustat->idle, cputime64);
}
#ifndef CONFIG_VIRT_CPU_ACCOUNTING
#ifdef CONFIG_IRQ_TIME_ACCOUNTING
/*
* Account a tick to a process and cpustat
* @p: the process that the cpu time gets accounted to
* @user_tick: is the tick from userspace
* @rq: the pointer to rq
*
* Tick demultiplexing follows the order
* - pending hardirq update
* - pending softirq update
* - user_time
* - idle_time
* - system time
* - check for guest_time
* - else account as system_time
*
* Check for hardirq is done both for system and user time as there is
* no timer going off while we are on hardirq and hence we may never get an
* opportunity to update it solely in system time.
* p->stime and friends are only updated on system time and not on irq
* softirq as those do not count in task exec_runtime any more.
*/
static void irqtime_account_process_tick(struct task_struct *p, int user_tick,
struct rq *rq)
{
cputime_t one_jiffy_scaled = cputime_to_scaled(cputime_one_jiffy);
cputime64_t tmp = cputime_to_cputime64(cputime_one_jiffy);
struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat;
if (irqtime_account_hi_update()) {
cpustat->irq = cputime64_add(cpustat->irq, tmp);
} else if (irqtime_account_si_update()) {
cpustat->softirq = cputime64_add(cpustat->softirq, tmp);
} else if (this_cpu_ksoftirqd() == p) {
/*
* ksoftirqd time do not get accounted in cpu_softirq_time.
* So, we have to handle it separately here.
* Also, p->stime needs to be updated for ksoftirqd.
*/
__account_system_time(p, cputime_one_jiffy, one_jiffy_scaled,
&cpustat->softirq);
} else if (user_tick) {
account_user_time(p, cputime_one_jiffy, one_jiffy_scaled);
} else if (p == rq->idle) {
account_idle_time(cputime_one_jiffy);
} else if (p->flags & PF_VCPU) { /* System time or guest time */
account_guest_time(p, cputime_one_jiffy, one_jiffy_scaled);
} else {
__account_system_time(p, cputime_one_jiffy, one_jiffy_scaled,
&cpustat->system);
}
}
static void irqtime_account_idle_ticks(int ticks)
{
int i;
struct rq *rq = this_rq();
for (i = 0; i < ticks; i++)
irqtime_account_process_tick(current, 0, rq);
}
#else /* CONFIG_IRQ_TIME_ACCOUNTING */
static void irqtime_account_idle_ticks(int ticks) {}
static void irqtime_account_process_tick(struct task_struct *p, int user_tick,
struct rq *rq) {}
#endif /* CONFIG_IRQ_TIME_ACCOUNTING */
/*
* Account a single tick of cpu time.
* @p: the process that the cpu time gets accounted to
* @user_tick: indicates if the tick is a user or a system tick
*/
void account_process_tick(struct task_struct *p, int user_tick)
{
cputime_t one_jiffy_scaled = cputime_to_scaled(cputime_one_jiffy);
struct rq *rq = this_rq();
if (sched_clock_irqtime) {
irqtime_account_process_tick(p, user_tick, rq);
return;
}
if (user_tick)
account_user_time(p, cputime_one_jiffy, one_jiffy_scaled);
else if ((p != rq->idle) || (irq_count() != HARDIRQ_OFFSET))
account_system_time(p, HARDIRQ_OFFSET, cputime_one_jiffy,
one_jiffy_scaled);
else
account_idle_time(cputime_one_jiffy);
}
/*
* Account multiple ticks of steal time.
* @p: the process from which the cpu time has been stolen
* @ticks: number of stolen ticks
*/
void account_steal_ticks(unsigned long ticks)
{
account_steal_time(jiffies_to_cputime(ticks));
}
/*
* Account multiple ticks of idle time.
* @ticks: number of stolen ticks
*/
void account_idle_ticks(unsigned long ticks)
{
if (sched_clock_irqtime) {
irqtime_account_idle_ticks(ticks);
return;
}
account_idle_time(jiffies_to_cputime(ticks));
}
#endif
/*
* Use precise platform statistics if available:
*/
#ifdef CONFIG_VIRT_CPU_ACCOUNTING
void task_times(struct task_struct *p, cputime_t *ut, cputime_t *st)
{
*ut = p->utime;
*st = p->stime;
}
void thread_group_times(struct task_struct *p, cputime_t *ut, cputime_t *st)
{
struct task_cputime cputime;
thread_group_cputime(p, &cputime);
*ut = cputime.utime;
*st = cputime.stime;
}
#else
#ifndef nsecs_to_cputime
# define nsecs_to_cputime(__nsecs) nsecs_to_jiffies(__nsecs)
#endif
void task_times(struct task_struct *p, cputime_t *ut, cputime_t *st)
{
cputime_t rtime, utime = p->utime, total = cputime_add(utime, p->stime);
/*
* Use CFS's precise accounting:
*/
rtime = nsecs_to_cputime(p->se.sum_exec_runtime);
if (total) {
u64 temp = rtime;
temp *= utime;
do_div(temp, total);
utime = (cputime_t)temp;
} else
utime = rtime;
/*
* Compare with previous values, to keep monotonicity:
*/
p->prev_utime = max(p->prev_utime, utime);
p->prev_stime = max(p->prev_stime, cputime_sub(rtime, p->prev_utime));
*ut = p->prev_utime;
*st = p->prev_stime;
}
/*
* Must be called with siglock held.
*/
void thread_group_times(struct task_struct *p, cputime_t *ut, cputime_t *st)
{
struct signal_struct *sig = p->signal;
struct task_cputime cputime;
cputime_t rtime, utime, total;
thread_group_cputime(p, &cputime);
total = cputime_add(cputime.utime, cputime.stime);
rtime = nsecs_to_cputime(cputime.sum_exec_runtime);
if (total) {
u64 temp = rtime;
temp *= cputime.utime;
do_div(temp, total);
utime = (cputime_t)temp;
} else
utime = rtime;
sig->prev_utime = max(sig->prev_utime, utime);
sig->prev_stime = max(sig->prev_stime,
cputime_sub(rtime, sig->prev_utime));
*ut = sig->prev_utime;
*st = sig->prev_stime;
}
#endif
/*
* This function gets called by the timer code, with HZ frequency.
* We call it with interrupts disabled.
*/
void scheduler_tick(void)
{
int cpu = smp_processor_id();
struct rq *rq = cpu_rq(cpu);
struct task_struct *curr = rq->curr;
sched_clock_tick();
raw_spin_lock(&rq->lock);
update_rq_clock(rq);
update_cpu_load_active(rq);
curr->sched_class->task_tick(rq, curr, 0);
raw_spin_unlock(&rq->lock);
perf_event_task_tick();
#ifdef CONFIG_SMP
rq->idle_at_tick = idle_cpu(cpu);
trigger_load_balance(rq, cpu);
#endif
}
notrace unsigned long get_parent_ip(unsigned long addr)
{
if (in_lock_functions(addr)) {
addr = CALLER_ADDR2;
if (in_lock_functions(addr))
addr = CALLER_ADDR3;
}
return addr;
}
#if defined(CONFIG_PREEMPT) && (defined(CONFIG_DEBUG_PREEMPT) || \
defined(CONFIG_PREEMPT_TRACER))
void __kprobes add_preempt_count(int val)
{
#ifdef CONFIG_DEBUG_PREEMPT
/*
* Underflow?
*/
if (DEBUG_LOCKS_WARN_ON((preempt_count() < 0)))
return;
#endif
preempt_count() += val;
#ifdef CONFIG_DEBUG_PREEMPT
/*
* Spinlock count overflowing soon?
*/
DEBUG_LOCKS_WARN_ON((preempt_count() & PREEMPT_MASK) >=
PREEMPT_MASK - 10);
#endif
if (preempt_count() == val)
trace_preempt_off(CALLER_ADDR0, get_parent_ip(CALLER_ADDR1));
}
EXPORT_SYMBOL(add_preempt_count);
void __kprobes sub_preempt_count(int val)
{
#ifdef CONFIG_DEBUG_PREEMPT
/*
* Underflow?
*/
if (DEBUG_LOCKS_WARN_ON(val > preempt_count()))
return;
/*
* Is the spinlock portion underflowing?
*/
if (DEBUG_LOCKS_WARN_ON((val < PREEMPT_MASK) &&
!(preempt_count() & PREEMPT_MASK)))
return;
#endif
if (preempt_count() == val)
trace_preempt_on(CALLER_ADDR0, get_parent_ip(CALLER_ADDR1));
preempt_count() -= val;
}
EXPORT_SYMBOL(sub_preempt_count);
#endif
/*
* Print scheduling while atomic bug:
*/
static noinline void __schedule_bug(struct task_struct *prev)
{
struct pt_regs *regs = get_irq_regs();
printk(KERN_ERR "BUG: scheduling while atomic: %s/%d/0x%08x\n",
prev->comm, prev->pid, preempt_count());
debug_show_held_locks(prev);
print_modules();
if (irqs_disabled())
print_irqtrace_events(prev);
if (regs)
show_regs(regs);
else
dump_stack();
}
/*
* Various schedule()-time debugging checks and statistics:
*/
static inline void schedule_debug(struct task_struct *prev)
{
/*
* Test if we are atomic. Since do_exit() needs to call into
* schedule() atomically, we ignore that path for now.
* Otherwise, whine if we are scheduling when we should not be.
*/
if (unlikely(in_atomic_preempt_off() && !prev->exit_state))
__schedule_bug(prev);
profile_hit(SCHED_PROFILING, __builtin_return_address(0));
schedstat_inc(this_rq(), sched_count);
}
static void put_prev_task(struct rq *rq, struct task_struct *prev)
{
if (prev->on_rq || rq->skip_clock_update < 0)
update_rq_clock(rq);
prev->sched_class->put_prev_task(rq, prev);
}
/*
* Pick up the highest-prio task:
*/
static inline struct task_struct *
pick_next_task(struct rq *rq)
{
const struct sched_class *class;
struct task_struct *p;
/*
* Optimization: we know that if all tasks are in
* the fair class we can call that function directly:
*/
if (likely(rq->nr_running == rq->cfs.nr_running)) {
p = fair_sched_class.pick_next_task(rq);
if (likely(p))
return p;
}
for_each_class(class) {
p = class->pick_next_task(rq);
if (p)
return p;
}
BUG(); /* the idle class will always have a runnable task */
}
/*
* schedule() is the main scheduler function.
*/
asmlinkage void __sched schedule(void)
{
struct task_struct *prev, *next;
unsigned long *switch_count;
struct rq *rq;
int cpu;
need_resched:
preempt_disable();
cpu = smp_processor_id();
rq = cpu_rq(cpu);
rcu_note_context_switch(cpu);
prev = rq->curr;
schedule_debug(prev);
if (sched_feat(HRTICK))
hrtick_clear(rq);
raw_spin_lock_irq(&rq->lock);
switch_count = &prev->nivcsw;
if (prev->state && !(preempt_count() & PREEMPT_ACTIVE)) {
if (unlikely(signal_pending_state(prev->state, prev))) {
prev->state = TASK_RUNNING;
} else {
deactivate_task(rq, prev, DEQUEUE_SLEEP);
prev->on_rq = 0;
/*
* If a worker went to sleep, notify and ask workqueue
* whether it wants to wake up a task to maintain
* concurrency.
*/
if (prev->flags & PF_WQ_WORKER) {
struct task_struct *to_wakeup;
to_wakeup = wq_worker_sleeping(prev, cpu);
if (to_wakeup)
try_to_wake_up_local(to_wakeup);
}
/*
* If we are going to sleep and we have plugged IO
* queued, make sure to submit it to avoid deadlocks.
*/
if (blk_needs_flush_plug(prev)) {
raw_spin_unlock(&rq->lock);
blk_schedule_flush_plug(prev);
raw_spin_lock(&rq->lock);
}
}
switch_count = &prev->nvcsw;
}
pre_schedule(rq, prev);
if (unlikely(!rq->nr_running))
idle_balance(cpu, rq);
put_prev_task(rq, prev);
next = pick_next_task(rq);
clear_tsk_need_resched(prev);
rq->skip_clock_update = 0;
if (likely(prev != next)) {
rq->nr_switches++;
rq->curr = next;
++*switch_count;
context_switch(rq, prev, next); /* unlocks the rq */
/*
* The context switch have flipped the stack from under us
* and restored the local variables which were saved when
* this task called schedule() in the past. prev == current
* is still correct, but it can be moved to another cpu/rq.
*/
cpu = smp_processor_id();
rq = cpu_rq(cpu);
} else
raw_spin_unlock_irq(&rq->lock);
post_schedule(rq);
preempt_enable_no_resched();
if (need_resched())
goto need_resched;
}
EXPORT_SYMBOL(schedule);
#ifdef CONFIG_MUTEX_SPIN_ON_OWNER
static inline bool owner_running(struct mutex *lock, struct task_struct *owner)
{
if (lock->owner != owner)
return false;
/*
* Ensure we emit the owner->on_cpu, dereference _after_ checking
* lock->owner still matches owner, if that fails, owner might
* point to free()d memory, if it still matches, the rcu_read_lock()
* ensures the memory stays valid.
*/
barrier();
return owner->on_cpu;
}
/*
* Look out! "owner" is an entirely speculative pointer
* access and not reliable.
*/
int mutex_spin_on_owner(struct mutex *lock, struct task_struct *owner)
{
if (!sched_feat(OWNER_SPIN))
return 0;
rcu_read_lock();
while (owner_running(lock, owner)) {
if (need_resched())
break;
arch_mutex_cpu_relax();
}
rcu_read_unlock();
/*
* We break out the loop above on need_resched() and when the
* owner changed, which is a sign for heavy contention. Return
* success only when lock->owner is NULL.
*/
return lock->owner == NULL;
}
#endif
#ifdef CONFIG_PREEMPT
/*
* this is the entry point to schedule() from in-kernel preemption
* off of preempt_enable. Kernel preemptions off return from interrupt
* occur there and call schedule directly.
*/
asmlinkage void __sched notrace preempt_schedule(void)
{
struct thread_info *ti = current_thread_info();
/*
* If there is a non-zero preempt_count or interrupts are disabled,
* we do not want to preempt the current task. Just return..
*/
if (likely(ti->preempt_count || irqs_disabled()))
return;
do {
add_preempt_count_notrace(PREEMPT_ACTIVE);
schedule();
sub_preempt_count_notrace(PREEMPT_ACTIVE);
/*
* Check again in case we missed a preemption opportunity
* between schedule and now.
*/
barrier();
} while (need_resched());
}
EXPORT_SYMBOL(preempt_schedule);
/*
* this is the entry point to schedule() from kernel preemption
* off of irq context.
* Note, that this is called and return with irqs disabled. This will
* protect us against recursive calling from irq.
*/
asmlinkage void __sched preempt_schedule_irq(void)
{
struct thread_info *ti = current_thread_info();
/* Catch callers which need to be fixed */
BUG_ON(ti->preempt_count || !irqs_disabled());
do {
add_preempt_count(PREEMPT_ACTIVE);
local_irq_enable();
schedule();
local_irq_disable();
sub_preempt_count(PREEMPT_ACTIVE);
/*
* Check again in case we missed a preemption opportunity
* between schedule and now.
*/
barrier();
} while (need_resched());
}
#endif /* CONFIG_PREEMPT */
int default_wake_function(wait_queue_t *curr, unsigned mode, int wake_flags,
void *key)
{
return try_to_wake_up(curr->private, mode, wake_flags);
}
EXPORT_SYMBOL(default_wake_function);
/*
* The core wakeup function. Non-exclusive wakeups (nr_exclusive == 0) just
* wake everything up. If it's an exclusive wakeup (nr_exclusive == small +ve
* number) then we wake all the non-exclusive tasks and one exclusive task.
*
* There are circumstances in which we can try to wake a task which has already
* started to run but is not in state TASK_RUNNING. try_to_wake_up() returns
* zero in this (rare) case, and we handle it by continuing to scan the queue.
*/
static void __wake_up_common(wait_queue_head_t *q, unsigned int mode,
int nr_exclusive, int wake_flags, void *key)
{
wait_queue_t *curr, *next;
list_for_each_entry_safe(curr, next, &q->task_list, task_list) {
unsigned flags = curr->flags;
if (curr->func(curr, mode, wake_flags, key) &&
(flags & WQ_FLAG_EXCLUSIVE) && !--nr_exclusive)
break;
}
}
/**
* __wake_up - wake up threads blocked on a waitqueue.
* @q: the waitqueue
* @mode: which threads
* @nr_exclusive: how many wake-one or wake-many threads to wake up
* @key: is directly passed to the wakeup function
*
* It may be assumed that this function implies a write memory barrier before
* changing the task state if and only if any tasks are woken up.
*/
void __wake_up(wait_queue_head_t *q, unsigned int mode,
int nr_exclusive, void *key)
{
unsigned long flags;
spin_lock_irqsave(&q->lock, flags);
__wake_up_common(q, mode, nr_exclusive, 0, key);
spin_unlock_irqrestore(&q->lock, flags);
}
EXPORT_SYMBOL(__wake_up);
/*
* Same as __wake_up but called with the spinlock in wait_queue_head_t held.
*/
void __wake_up_locked(wait_queue_head_t *q, unsigned int mode)
{
__wake_up_common(q, mode, 1, 0, NULL);
}
EXPORT_SYMBOL_GPL(__wake_up_locked);
void __wake_up_locked_key(wait_queue_head_t *q, unsigned int mode, void *key)
{
__wake_up_common(q, mode, 1, 0, key);
}
EXPORT_SYMBOL_GPL(__wake_up_locked_key);
/**
* __wake_up_sync_key - wake up threads blocked on a waitqueue.
* @q: the waitqueue
* @mode: which threads
* @nr_exclusive: how many wake-one or wake-many threads to wake up
* @key: opaque value to be passed to wakeup targets
*
* The sync wakeup differs that the waker knows that it will schedule
* away soon, so while the target thread will be woken up, it will not
* be migrated to another CPU - ie. the two threads are 'synchronized'
* with each other. This can prevent needless bouncing between CPUs.
*
* On UP it can prevent extra preemption.
*
* It may be assumed that this function implies a write memory barrier before
* changing the task state if and only if any tasks are woken up.
*/
void __wake_up_sync_key(wait_queue_head_t *q, unsigned int mode,
int nr_exclusive, void *key)
{
unsigned long flags;
int wake_flags = WF_SYNC;
if (unlikely(!q))
return;
if (unlikely(!nr_exclusive))
wake_flags = 0;
spin_lock_irqsave(&q->lock, flags);
__wake_up_common(q, mode, nr_exclusive, wake_flags, key);
spin_unlock_irqrestore(&q->lock, flags);
}
EXPORT_SYMBOL_GPL(__wake_up_sync_key);
/*
* __wake_up_sync - see __wake_up_sync_key()
*/
void __wake_up_sync(wait_queue_head_t *q, unsigned int mode, int nr_exclusive)
{
__wake_up_sync_key(q, mode, nr_exclusive, NULL);
}
EXPORT_SYMBOL_GPL(__wake_up_sync); /* For internal use only */
/**
* complete: - signals a single thread waiting on this completion
* @x: holds the state of this particular completion
*
* This will wake up a single thread waiting on this completion. Threads will be
* awakened in the same order in which they were queued.
*
* See also complete_all(), wait_for_completion() and related routines.
*
* It may be assumed that this function implies a write memory barrier before
* changing the task state if and only if any tasks are woken up.
*/
void complete(struct completion *x)
{
unsigned long flags;
spin_lock_irqsave(&x->wait.lock, flags);
x->done++;
__wake_up_common(&x->wait, TASK_NORMAL, 1, 0, NULL);
spin_unlock_irqrestore(&x->wait.lock, flags);
}
EXPORT_SYMBOL(complete);
/**
* complete_all: - signals all threads waiting on this completion
* @x: holds the state of this particular completion
*
* This will wake up all threads waiting on this particular completion event.
*
* It may be assumed that this function implies a write memory barrier before
* changing the task state if and only if any tasks are woken up.
*/
void complete_all(struct completion *x)
{
unsigned long flags;
spin_lock_irqsave(&x->wait.lock, flags);
x->done += UINT_MAX/2;
__wake_up_common(&x->wait, TASK_NORMAL, 0, 0, NULL);
spin_unlock_irqrestore(&x->wait.lock, flags);
}
EXPORT_SYMBOL(complete_all);
static inline long __sched
do_wait_for_common(struct completion *x, long timeout, int state)
{
if (!x->done) {
DECLARE_WAITQUEUE(wait, current);
__add_wait_queue_tail_exclusive(&x->wait, &wait);
do {
if (signal_pending_state(state, current)) {
timeout = -ERESTARTSYS;
break;
}
__set_current_state(state);
spin_unlock_irq(&x->wait.lock);
timeout = schedule_timeout(timeout);
spin_lock_irq(&x->wait.lock);
} while (!x->done && timeout);
__remove_wait_queue(&x->wait, &wait);
if (!x->done)
return timeout;
}
x->done--;
return timeout ?: 1;
}
static long __sched
wait_for_common(struct completion *x, long timeout, int state)
{
might_sleep();
spin_lock_irq(&x->wait.lock);
timeout = do_wait_for_common(x, timeout, state);
spin_unlock_irq(&x->wait.lock);
return timeout;
}
/**
* wait_for_completion: - waits for completion of a task
* @x: holds the state of this particular completion
*
* This waits to be signaled for completion of a specific task. It is NOT
* interruptible and there is no timeout.
*
* See also similar routines (i.e. wait_for_completion_timeout()) with timeout
* and interrupt capability. Also see complete().
*/
void __sched wait_for_completion(struct completion *x)
{
wait_for_common(x, MAX_SCHEDULE_TIMEOUT, TASK_UNINTERRUPTIBLE);
}
EXPORT_SYMBOL(wait_for_completion);
/**
* wait_for_completion_timeout: - waits for completion of a task (w/timeout)
* @x: holds the state of this particular completion
* @timeout: timeout value in jiffies
*
* This waits for either a completion of a specific task to be signaled or for a
* specified timeout to expire. The timeout is in jiffies. It is not
* interruptible.
*/
unsigned long __sched
wait_for_completion_timeout(struct completion *x, unsigned long timeout)
{
return wait_for_common(x, timeout, TASK_UNINTERRUPTIBLE);
}
EXPORT_SYMBOL(wait_for_completion_timeout);
/**
* wait_for_completion_interruptible: - waits for completion of a task (w/intr)
* @x: holds the state of this particular completion
*
* This waits for completion of a specific task to be signaled. It is
* interruptible.
*/
int __sched wait_for_completion_interruptible(struct completion *x)
{
long t = wait_for_common(x, MAX_SCHEDULE_TIMEOUT, TASK_INTERRUPTIBLE);
if (t == -ERESTARTSYS)
return t;
return 0;
}
EXPORT_SYMBOL(wait_for_completion_interruptible);
/**
* wait_for_completion_interruptible_timeout: - waits for completion (w/(to,intr))
* @x: holds the state of this particular completion
* @timeout: timeout value in jiffies
*
* This waits for either a completion of a specific task to be signaled or for a
* specified timeout to expire. It is interruptible. The timeout is in jiffies.
*/
long __sched
wait_for_completion_interruptible_timeout(struct completion *x,
unsigned long timeout)
{
return wait_for_common(x, timeout, TASK_INTERRUPTIBLE);
}
EXPORT_SYMBOL(wait_for_completion_interruptible_timeout);
/**
* wait_for_completion_killable: - waits for completion of a task (killable)
* @x: holds the state of this particular completion
*
* This waits to be signaled for completion of a specific task. It can be
* interrupted by a kill signal.
*/
int __sched wait_for_completion_killable(struct completion *x)
{
long t = wait_for_common(x, MAX_SCHEDULE_TIMEOUT, TASK_KILLABLE);
if (t == -ERESTARTSYS)
return t;
return 0;
}
EXPORT_SYMBOL(wait_for_completion_killable);
/**
* wait_for_completion_killable_timeout: - waits for completion of a task (w/(to,killable))
* @x: holds the state of this particular completion
* @timeout: timeout value in jiffies
*
* This waits for either a completion of a specific task to be
* signaled or for a specified timeout to expire. It can be
* interrupted by a kill signal. The timeout is in jiffies.
*/
long __sched
wait_for_completion_killable_timeout(struct completion *x,
unsigned long timeout)
{
return wait_for_common(x, timeout, TASK_KILLABLE);
}
EXPORT_SYMBOL(wait_for_completion_killable_timeout);
/**
* try_wait_for_completion - try to decrement a completion without blocking
* @x: completion structure
*
* Returns: 0 if a decrement cannot be done without blocking
* 1 if a decrement succeeded.
*
* If a completion is being used as a counting completion,
* attempt to decrement the counter without blocking. This
* enables us to avoid waiting if the resource the completion
* is protecting is not available.
*/
bool try_wait_for_completion(struct completion *x)
{
unsigned long flags;
int ret = 1;
spin_lock_irqsave(&x->wait.lock, flags);
if (!x->done)
ret = 0;
else
x->done--;
spin_unlock_irqrestore(&x->wait.lock, flags);
return ret;
}
EXPORT_SYMBOL(try_wait_for_completion);
/**
* completion_done - Test to see if a completion has any waiters
* @x: completion structure
*
* Returns: 0 if there are waiters (wait_for_completion() in progress)
* 1 if there are no waiters.
*
*/
bool completion_done(struct completion *x)
{
unsigned long flags;
int ret = 1;
spin_lock_irqsave(&x->wait.lock, flags);
if (!x->done)
ret = 0;
spin_unlock_irqrestore(&x->wait.lock, flags);
return ret;
}
EXPORT_SYMBOL(completion_done);
static long __sched
sleep_on_common(wait_queue_head_t *q, int state, long timeout)
{
unsigned long flags;
wait_queue_t wait;
init_waitqueue_entry(&wait, current);
__set_current_state(state);
spin_lock_irqsave(&q->lock, flags);
__add_wait_queue(q, &wait);
spin_unlock(&q->lock);
timeout = schedule_timeout(timeout);
spin_lock_irq(&q->lock);
__remove_wait_queue(q, &wait);
spin_unlock_irqrestore(&q->lock, flags);
return timeout;
}
void __sched interruptible_sleep_on(wait_queue_head_t *q)
{
sleep_on_common(q, TASK_INTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT);
}
EXPORT_SYMBOL(interruptible_sleep_on);
long __sched
interruptible_sleep_on_timeout(wait_queue_head_t *q, long timeout)
{
return sleep_on_common(q, TASK_INTERRUPTIBLE, timeout);
}
EXPORT_SYMBOL(interruptible_sleep_on_timeout);
void __sched sleep_on(wait_queue_head_t *q)
{
sleep_on_common(q, TASK_UNINTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT);
}
EXPORT_SYMBOL(sleep_on);
long __sched sleep_on_timeout(wait_queue_head_t *q, long timeout)
{
return sleep_on_common(q, TASK_UNINTERRUPTIBLE, timeout);
}
EXPORT_SYMBOL(sleep_on_timeout);
#ifdef CONFIG_RT_MUTEXES
/*
* rt_mutex_setprio - set the current priority of a task
* @p: task
* @prio: prio value (kernel-internal form)
*
* This function changes the 'effective' priority of a task. It does
* not touch ->normal_prio like __setscheduler().
*
* Used by the rt_mutex code to implement priority inheritance logic.
*/
void rt_mutex_setprio(struct task_struct *p, int prio)
{
int oldprio, on_rq, running;
struct rq *rq;
const struct sched_class *prev_class;
BUG_ON(prio < 0 || prio > MAX_PRIO);
rq = __task_rq_lock(p);
trace_sched_pi_setprio(p, prio);
oldprio = p->prio;
prev_class = p->sched_class;
on_rq = p->on_rq;
running = task_current(rq, p);
if (on_rq)
dequeue_task(rq, p, 0);
if (running)
p->sched_class->put_prev_task(rq, p);
if (rt_prio(prio))
p->sched_class = &rt_sched_class;
else
p->sched_class = &fair_sched_class;
p->prio = prio;
if (running)
p->sched_class->set_curr_task(rq);
if (on_rq)
enqueue_task(rq, p, oldprio < prio ? ENQUEUE_HEAD : 0);
check_class_changed(rq, p, prev_class, oldprio);
__task_rq_unlock(rq);
}
#endif
void set_user_nice(struct task_struct *p, long nice)
{
int old_prio, delta, on_rq;
unsigned long flags;
struct rq *rq;
if (TASK_NICE(p) == nice || nice < -20 || nice > 19)
return;
/*
* We have to be careful, if called from sys_setpriority(),
* the task might be in the middle of scheduling on another CPU.
*/
rq = task_rq_lock(p, &flags);
/*
* The RT priorities are set via sched_setscheduler(), but we still
* allow the 'normal' nice value to be set - but as expected
* it wont have any effect on scheduling until the task is
* SCHED_FIFO/SCHED_RR:
*/
if (task_has_rt_policy(p)) {
p->static_prio = NICE_TO_PRIO(nice);
goto out_unlock;
}
on_rq = p->on_rq;
if (on_rq)
dequeue_task(rq, p, 0);
p->static_prio = NICE_TO_PRIO(nice);
set_load_weight(p);
old_prio = p->prio;
p->prio = effective_prio(p);
delta = p->prio - old_prio;
if (on_rq) {
enqueue_task(rq, p, 0);
/*
* If the task increased its priority or is running and
* lowered its priority, then reschedule its CPU:
*/
if (delta < 0 || (delta > 0 && task_running(rq, p)))
resched_task(rq->curr);
}
out_unlock:
task_rq_unlock(rq, p, &flags);
}
EXPORT_SYMBOL(set_user_nice);
/*
* can_nice - check if a task can reduce its nice value
* @p: task
* @nice: nice value
*/
int can_nice(const struct task_struct *p, const int nice)
{
/* convert nice value [19,-20] to rlimit style value [1,40] */
int nice_rlim = 20 - nice;
return (nice_rlim <= task_rlimit(p, RLIMIT_NICE) ||
capable(CAP_SYS_NICE));
}
#ifdef __ARCH_WANT_SYS_NICE
/*
* sys_nice - change the priority of the current process.
* @increment: priority increment
*
* sys_setpriority is a more generic, but much slower function that
* does similar things.
*/
SYSCALL_DEFINE1(nice, int, increment)
{
long nice, retval;
/*
* Setpriority might change our priority at the same moment.
* We don't have to worry. Conceptually one call occurs first
* and we have a single winner.
*/
if (increment < -40)
increment = -40;
if (increment > 40)
increment = 40;
nice = TASK_NICE(current) + increment;
if (nice < -20)
nice = -20;
if (nice > 19)
nice = 19;
if (increment < 0 && !can_nice(current, nice))
return -EPERM;
retval = security_task_setnice(current, nice);
if (retval)
return retval;
set_user_nice(current, nice);
return 0;
}
#endif
/**
* task_prio - return the priority value of a given task.
* @p: the task in question.
*
* This is the priority value as seen by users in /proc.
* RT tasks are offset by -200. Normal tasks are centered
* around 0, value goes from -16 to +15.
*/
int task_prio(const struct task_struct *p)
{
return p->prio - MAX_RT_PRIO;
}
/**
* task_nice - return the nice value of a given task.
* @p: the task in question.
*/
int task_nice(const struct task_struct *p)
{
return TASK_NICE(p);
}
EXPORT_SYMBOL(task_nice);
/**
* idle_cpu - is a given cpu idle currently?
* @cpu: the processor in question.
*/
int idle_cpu(int cpu)
{
return cpu_curr(cpu) == cpu_rq(cpu)->idle;
}
/**
* idle_task - return the idle task for a given cpu.
* @cpu: the processor in question.
*/
struct task_struct *idle_task(int cpu)
{
return cpu_rq(cpu)->idle;
}
/**
* find_process_by_pid - find a process with a matching PID value.
* @pid: the pid in question.
*/
static struct task_struct *find_process_by_pid(pid_t pid)
{
return pid ? find_task_by_vpid(pid) : current;
}
/* Actually do priority change: must hold rq lock. */
static void
__setscheduler(struct rq *rq, struct task_struct *p, int policy, int prio)
{
p->policy = policy;
p->rt_priority = prio;
p->normal_prio = normal_prio(p);
/* we are holding p->pi_lock already */
p->prio = rt_mutex_getprio(p);
if (rt_prio(p->prio))
p->sched_class = &rt_sched_class;
else
p->sched_class = &fair_sched_class;
set_load_weight(p);
}
/*
* check the target process has a UID that matches the current process's
*/
static bool check_same_owner(struct task_struct *p)
{
const struct cred *cred = current_cred(), *pcred;
bool match;
rcu_read_lock();
pcred = __task_cred(p);
if (cred->user->user_ns == pcred->user->user_ns)
match = (cred->euid == pcred->euid ||
cred->euid == pcred->uid);
else
match = false;
rcu_read_unlock();
return match;
}
static int __sched_setscheduler(struct task_struct *p, int policy,
const struct sched_param *param, bool user)
{
int retval, oldprio, oldpolicy = -1, on_rq, running;
unsigned long flags;
const struct sched_class *prev_class;
struct rq *rq;
int reset_on_fork;
/* may grab non-irq protected spin_locks */
BUG_ON(in_interrupt());
recheck:
/* double check policy once rq lock held */
if (policy < 0) {
reset_on_fork = p->sched_reset_on_fork;
policy = oldpolicy = p->policy;
} else {
reset_on_fork = !!(policy & SCHED_RESET_ON_FORK);
policy &= ~SCHED_RESET_ON_FORK;
if (policy != SCHED_FIFO && policy != SCHED_RR &&
policy != SCHED_NORMAL && policy != SCHED_BATCH &&
policy != SCHED_IDLE)
return -EINVAL;
}
/*
* Valid priorities for SCHED_FIFO and SCHED_RR are
* 1..MAX_USER_RT_PRIO-1, valid priority for SCHED_NORMAL,
* SCHED_BATCH and SCHED_IDLE is 0.
*/
if (param->sched_priority < 0 ||
(p->mm && param->sched_priority > MAX_USER_RT_PRIO-1) ||
(!p->mm && param->sched_priority > MAX_RT_PRIO-1))
return -EINVAL;
if (rt_policy(policy) != (param->sched_priority != 0))
return -EINVAL;
/*
* Allow unprivileged RT tasks to decrease priority:
*/
if (user && !capable(CAP_SYS_NICE)) {
if (rt_policy(policy)) {
unsigned long rlim_rtprio =
task_rlimit(p, RLIMIT_RTPRIO);
/* can't set/change the rt policy */
if (policy != p->policy && !rlim_rtprio)
return -EPERM;
/* can't increase priority */
if (param->sched_priority > p->rt_priority &&
param->sched_priority > rlim_rtprio)
return -EPERM;
}
/*
* Treat SCHED_IDLE as nice 20. Only allow a switch to
* SCHED_NORMAL if the RLIMIT_NICE would normally permit it.
*/
if (p->policy == SCHED_IDLE && policy != SCHED_IDLE) {
if (!can_nice(p, TASK_NICE(p)))
return -EPERM;
}
/* can't change other user's priorities */
if (!check_same_owner(p))
return -EPERM;
/* Normal users shall not reset the sched_reset_on_fork flag */
if (p->sched_reset_on_fork && !reset_on_fork)
return -EPERM;
}
if (user) {
retval = security_task_setscheduler(p);
if (retval)
return retval;
}
/*
* make sure no PI-waiters arrive (or leave) while we are
* changing the priority of the task:
*
* To be able to change p->policy safely, the appropriate
* runqueue lock must be held.
*/
rq = task_rq_lock(p, &flags);
/*
* Changing the policy of the stop threads its a very bad idea
*/
if (p == rq->stop) {
task_rq_unlock(rq, p, &flags);
return -EINVAL;
}
/*
* If not changing anything there's no need to proceed further:
*/
if (unlikely(policy == p->policy && (!rt_policy(policy) ||
param->sched_priority == p->rt_priority))) {
__task_rq_unlock(rq);
raw_spin_unlock_irqrestore(&p->pi_lock, flags);
return 0;
}
#ifdef CONFIG_RT_GROUP_SCHED
if (user) {
/*
* Do not allow realtime tasks into groups that have no runtime
* assigned.
*/
if (rt_bandwidth_enabled() && rt_policy(policy) &&
task_group(p)->rt_bandwidth.rt_runtime == 0 &&
!task_group_is_autogroup(task_group(p))) {
task_rq_unlock(rq, p, &flags);
return -EPERM;
}
}
#endif
/* recheck policy now with rq lock held */
if (unlikely(oldpolicy != -1 && oldpolicy != p->policy)) {
policy = oldpolicy = -1;
task_rq_unlock(rq, p, &flags);
goto recheck;
}
on_rq = p->on_rq;
running = task_current(rq, p);
if (on_rq)
deactivate_task(rq, p, 0);
if (running)
p->sched_class->put_prev_task(rq, p);
p->sched_reset_on_fork = reset_on_fork;
oldprio = p->prio;
prev_class = p->sched_class;
__setscheduler(rq, p, policy, param->sched_priority);
if (running)
p->sched_class->set_curr_task(rq);
if (on_rq)
activate_task(rq, p, 0);
check_class_changed(rq, p, prev_class, oldprio);
task_rq_unlock(rq, p, &flags);
rt_mutex_adjust_pi(p);
return 0;
}
/**
* sched_setscheduler - change the scheduling policy and/or RT priority of a thread.
* @p: the task in question.
* @policy: new policy.
* @param: structure containing the new RT priority.
*
* NOTE that the task may be already dead.
*/
int sched_setscheduler(struct task_struct *p, int policy,
const struct sched_param *param)
{
return __sched_setscheduler(p, policy, param, true);
}
EXPORT_SYMBOL_GPL(sched_setscheduler);
/**
* sched_setscheduler_nocheck - change the scheduling policy and/or RT priority of a thread from kernelspace.
* @p: the task in question.
* @policy: new policy.
* @param: structure containing the new RT priority.
*
* Just like sched_setscheduler, only don't bother checking if the
* current context has permission. For example, this is needed in
* stop_machine(): we create temporary high priority worker threads,
* but our caller might not have that capability.
*/
int sched_setscheduler_nocheck(struct task_struct *p, int policy,
const struct sched_param *param)
{
return __sched_setscheduler(p, policy, param, false);
}
static int
do_sched_setscheduler(pid_t pid, int policy, struct sched_param __user *param)
{
struct sched_param lparam;
struct task_struct *p;
int retval;
if (!param || pid < 0)
return -EINVAL;
if (copy_from_user(&lparam, param, sizeof(struct sched_param)))
return -EFAULT;
rcu_read_lock();
retval = -ESRCH;
p = find_process_by_pid(pid);
if (p != NULL)
retval = sched_setscheduler(p, policy, &lparam);
rcu_read_unlock();
return retval;
}
/**
* sys_sched_setscheduler - set/change the scheduler policy and RT priority
* @pid: the pid in question.
* @policy: new policy.
* @param: structure containing the new RT priority.
*/
SYSCALL_DEFINE3(sched_setscheduler, pid_t, pid, int, policy,
struct sched_param __user *, param)
{
/* negative values for policy are not valid */
if (policy < 0)
return -EINVAL;
return do_sched_setscheduler(pid, policy, param);
}
/**
* sys_sched_setparam - set/change the RT priority of a thread
* @pid: the pid in question.
* @param: structure containing the new RT priority.
*/
SYSCALL_DEFINE2(sched_setparam, pid_t, pid, struct sched_param __user *, param)
{
return do_sched_setscheduler(pid, -1, param);
}
/**
* sys_sched_getscheduler - get the policy (scheduling class) of a thread
* @pid: the pid in question.
*/
SYSCALL_DEFINE1(sched_getscheduler, pid_t, pid)
{
struct task_struct *p;
int retval;
if (pid < 0)
return -EINVAL;
retval = -ESRCH;
rcu_read_lock();
p = find_process_by_pid(pid);
if (p) {
retval = security_task_getscheduler(p);
if (!retval)
retval = p->policy
| (p->sched_reset_on_fork ? SCHED_RESET_ON_FORK : 0);
}
rcu_read_unlock();
return retval;
}
/**
* sys_sched_getparam - get the RT priority of a thread
* @pid: the pid in question.
* @param: structure containing the RT priority.
*/
SYSCALL_DEFINE2(sched_getparam, pid_t, pid, struct sched_param __user *, param)
{
struct sched_param lp;
struct task_struct *p;
int retval;
if (!param || pid < 0)
return -EINVAL;
rcu_read_lock();
p = find_process_by_pid(pid);
retval = -ESRCH;
if (!p)
goto out_unlock;
retval = security_task_getscheduler(p);
if (retval)
goto out_unlock;
lp.sched_priority = p->rt_priority;
rcu_read_unlock();
/*
* This one might sleep, we cannot do it with a spinlock held ...
*/
retval = copy_to_user(param, &lp, sizeof(*param)) ? -EFAULT : 0;
return retval;
out_unlock:
rcu_read_unlock();
return retval;
}
long sched_setaffinity(pid_t pid, const struct cpumask *in_mask)
{
cpumask_var_t cpus_allowed, new_mask;
struct task_struct *p;
int retval;
get_online_cpus();
rcu_read_lock();
p = find_process_by_pid(pid);
if (!p) {
rcu_read_unlock();
put_online_cpus();
return -ESRCH;
}
/* Prevent p going away */
get_task_struct(p);
rcu_read_unlock();
if (!alloc_cpumask_var(&cpus_allowed, GFP_KERNEL)) {
retval = -ENOMEM;
goto out_put_task;
}
if (!alloc_cpumask_var(&new_mask, GFP_KERNEL)) {
retval = -ENOMEM;
goto out_free_cpus_allowed;
}
retval = -EPERM;
if (!check_same_owner(p) && !task_ns_capable(p, CAP_SYS_NICE))
goto out_unlock;
retval = security_task_setscheduler(p);
if (retval)
goto out_unlock;
cpuset_cpus_allowed(p, cpus_allowed);
cpumask_and(new_mask, in_mask, cpus_allowed);
again:
retval = set_cpus_allowed_ptr(p, new_mask);
if (!retval) {
cpuset_cpus_allowed(p, cpus_allowed);
if (!cpumask_subset(new_mask, cpus_allowed)) {
/*
* We must have raced with a concurrent cpuset
* update. Just reset the cpus_allowed to the
* cpuset's cpus_allowed
*/
cpumask_copy(new_mask, cpus_allowed);
goto again;
}
}
out_unlock:
free_cpumask_var(new_mask);
out_free_cpus_allowed:
free_cpumask_var(cpus_allowed);
out_put_task:
put_task_struct(p);
put_online_cpus();
return retval;
}
static int get_user_cpu_mask(unsigned long __user *user_mask_ptr, unsigned len,
struct cpumask *new_mask)
{
if (len < cpumask_size())
cpumask_clear(new_mask);
else if (len > cpumask_size())
len = cpumask_size();
return copy_from_user(new_mask, user_mask_ptr, len) ? -EFAULT : 0;
}
/**
* sys_sched_setaffinity - set the cpu affinity of a process
* @pid: pid of the process
* @len: length in bytes of the bitmask pointed to by user_mask_ptr
* @user_mask_ptr: user-space pointer to the new cpu mask
*/
SYSCALL_DEFINE3(sched_setaffinity, pid_t, pid, unsigned int, len,
unsigned long __user *, user_mask_ptr)
{
cpumask_var_t new_mask;
int retval;
if (!alloc_cpumask_var(&new_mask, GFP_KERNEL))
return -ENOMEM;
retval = get_user_cpu_mask(user_mask_ptr, len, new_mask);
if (retval == 0)
retval = sched_setaffinity(pid, new_mask);
free_cpumask_var(new_mask);
return retval;
}
long sched_getaffinity(pid_t pid, struct cpumask *mask)
{
struct task_struct *p;
unsigned long flags;
int retval;
get_online_cpus();
rcu_read_lock();
retval = -ESRCH;
p = find_process_by_pid(pid);
if (!p)
goto out_unlock;
retval = security_task_getscheduler(p);
if (retval)
goto out_unlock;
raw_spin_lock_irqsave(&p->pi_lock, flags);
cpumask_and(mask, &p->cpus_allowed, cpu_online_mask);
raw_spin_unlock_irqrestore(&p->pi_lock, flags);
out_unlock:
rcu_read_unlock();
put_online_cpus();
return retval;
}
/**
* sys_sched_getaffinity - get the cpu affinity of a process
* @pid: pid of the process
* @len: length in bytes of the bitmask pointed to by user_mask_ptr
* @user_mask_ptr: user-space pointer to hold the current cpu mask
*/
SYSCALL_DEFINE3(sched_getaffinity, pid_t, pid, unsigned int, len,
unsigned long __user *, user_mask_ptr)
{
int ret;
cpumask_var_t mask;
if ((len * BITS_PER_BYTE) < nr_cpu_ids)
return -EINVAL;
if (len & (sizeof(unsigned long)-1))
return -EINVAL;
if (!alloc_cpumask_var(&mask, GFP_KERNEL))
return -ENOMEM;
ret = sched_getaffinity(pid, mask);
if (ret == 0) {
size_t retlen = min_t(size_t, len, cpumask_size());
if (copy_to_user(user_mask_ptr, mask, retlen))
ret = -EFAULT;
else
ret = retlen;
}
free_cpumask_var(mask);
return ret;
}
/**
* sys_sched_yield - yield the current processor to other threads.
*
* This function yields the current CPU to other tasks. If there are no
* other threads running on this CPU then this function will return.
*/
SYSCALL_DEFINE0(sched_yield)
{
struct rq *rq = this_rq_lock();
schedstat_inc(rq, yld_count);
current->sched_class->yield_task(rq);
/*
* Since we are going to call schedule() anyway, there's
* no need to preempt or enable interrupts:
*/
__release(rq->lock);
spin_release(&rq->lock.dep_map, 1, _THIS_IP_);
do_raw_spin_unlock(&rq->lock);
preempt_enable_no_resched();
schedule();
return 0;
}
static inline int should_resched(void)
{
return need_resched() && !(preempt_count() & PREEMPT_ACTIVE);
}
static void __cond_resched(void)
{
add_preempt_count(PREEMPT_ACTIVE);
schedule();
sub_preempt_count(PREEMPT_ACTIVE);
}
int __sched _cond_resched(void)
{
if (should_resched()) {
__cond_resched();
return 1;
}
return 0;
}
EXPORT_SYMBOL(_cond_resched);
/*
* __cond_resched_lock() - if a reschedule is pending, drop the given lock,
* call schedule, and on return reacquire the lock.
*
* This works OK both with and without CONFIG_PREEMPT. We do strange low-level
* operations here to prevent schedule() from being called twice (once via
* spin_unlock(), once by hand).
*/
int __cond_resched_lock(spinlock_t *lock)
{
int resched = should_resched();
int ret = 0;
lockdep_assert_held(lock);
if (spin_needbreak(lock) || resched) {
spin_unlock(lock);
if (resched)
__cond_resched();
else
cpu_relax();
ret = 1;
spin_lock(lock);
}
return ret;
}
EXPORT_SYMBOL(__cond_resched_lock);
int __sched __cond_resched_softirq(void)
{
BUG_ON(!in_softirq());
if (should_resched()) {
local_bh_enable();
__cond_resched();
local_bh_disable();
return 1;
}
return 0;
}
EXPORT_SYMBOL(__cond_resched_softirq);
/**
* yield - yield the current processor to other threads.
*
* This is a shortcut for kernel-space yielding - it marks the
* thread runnable and calls sys_sched_yield().
*/
void __sched yield(void)
{
set_current_state(TASK_RUNNING);
sys_sched_yield();
}
EXPORT_SYMBOL(yield);
/**
* yield_to - yield the current processor to another thread in
* your thread group, or accelerate that thread toward the
* processor it's on.
* @p: target task
* @preempt: whether task preemption is allowed or not
*
* It's the caller's job to ensure that the target task struct
* can't go away on us before we can do any checks.
*
* Returns true if we indeed boosted the target task.
*/
bool __sched yield_to(struct task_struct *p, bool preempt)
{
struct task_struct *curr = current;
struct rq *rq, *p_rq;
unsigned long flags;
bool yielded = 0;
local_irq_save(flags);
rq = this_rq();
again:
p_rq = task_rq(p);
double_rq_lock(rq, p_rq);
while (task_rq(p) != p_rq) {
double_rq_unlock(rq, p_rq);
goto again;
}
if (!curr->sched_class->yield_to_task)
goto out;
if (curr->sched_class != p->sched_class)
goto out;
if (task_running(p_rq, p) || p->state)
goto out;
yielded = curr->sched_class->yield_to_task(rq, p, preempt);
if (yielded) {
schedstat_inc(rq, yld_count);
/*
* Make p's CPU reschedule; pick_next_entity takes care of
* fairness.
*/
if (preempt && rq != p_rq)
resched_task(p_rq->curr);
}
out:
double_rq_unlock(rq, p_rq);
local_irq_restore(flags);
if (yielded)
schedule();
return yielded;
}
EXPORT_SYMBOL_GPL(yield_to);
/*
* This task is about to go to sleep on IO. Increment rq->nr_iowait so
* that process accounting knows that this is a task in IO wait state.
*/
void __sched io_schedule(void)
{
struct rq *rq = raw_rq();
delayacct_blkio_start();
atomic_inc(&rq->nr_iowait);
blk_flush_plug(current);
current->in_iowait = 1;
schedule();
current->in_iowait = 0;
atomic_dec(&rq->nr_iowait);
delayacct_blkio_end();
}
EXPORT_SYMBOL(io_schedule);
long __sched io_schedule_timeout(long timeout)
{
struct rq *rq = raw_rq();
long ret;
delayacct_blkio_start();
atomic_inc(&rq->nr_iowait);
blk_flush_plug(current);
current->in_iowait = 1;
ret = schedule_timeout(timeout);
current->in_iowait = 0;
atomic_dec(&rq->nr_iowait);
delayacct_blkio_end();
return ret;
}
/**
* sys_sched_get_priority_max - return maximum RT priority.
* @policy: scheduling class.
*
* this syscall returns the maximum rt_priority that can be used
* by a given scheduling class.
*/
SYSCALL_DEFINE1(sched_get_priority_max, int, policy)
{
int ret = -EINVAL;
switch (policy) {
case SCHED_FIFO:
case SCHED_RR:
ret = MAX_USER_RT_PRIO-1;
break;
case SCHED_NORMAL:
case SCHED_BATCH:
case SCHED_IDLE:
ret = 0;
break;
}
return ret;
}
/**
* sys_sched_get_priority_min - return minimum RT priority.
* @policy: scheduling class.
*
* this syscall returns the minimum rt_priority that can be used
* by a given scheduling class.
*/
SYSCALL_DEFINE1(sched_get_priority_min, int, policy)
{
int ret = -EINVAL;
switch (policy) {
case SCHED_FIFO:
case SCHED_RR:
ret = 1;
break;
case SCHED_NORMAL:
case SCHED_BATCH:
case SCHED_IDLE:
ret = 0;
}
return ret;
}
/**
* sys_sched_rr_get_interval - return the default timeslice of a process.
* @pid: pid of the process.
* @interval: userspace pointer to the timeslice value.
*
* this syscall writes the default timeslice value of a given process
* into the user-space timespec buffer. A value of '0' means infinity.
*/
SYSCALL_DEFINE2(sched_rr_get_interval, pid_t, pid,
struct timespec __user *, interval)
{
struct task_struct *p;
unsigned int time_slice;
unsigned long flags;
struct rq *rq;
int retval;
struct timespec t;
if (pid < 0)
return -EINVAL;
retval = -ESRCH;
rcu_read_lock();
p = find_process_by_pid(pid);
if (!p)
goto out_unlock;
retval = security_task_getscheduler(p);
if (retval)
goto out_unlock;
rq = task_rq_lock(p, &flags);
time_slice = p->sched_class->get_rr_interval(rq, p);
task_rq_unlock(rq, p, &flags);
rcu_read_unlock();
jiffies_to_timespec(time_slice, &t);
retval = copy_to_user(interval, &t, sizeof(t)) ? -EFAULT : 0;
return retval;
out_unlock:
rcu_read_unlock();
return retval;
}
static const char stat_nam[] = TASK_STATE_TO_CHAR_STR;
void sched_show_task(struct task_struct *p)
{
unsigned long free = 0;
unsigned state;
state = p->state ? __ffs(p->state) + 1 : 0;
printk(KERN_INFO "%-15.15s %c", p->comm,
state < sizeof(stat_nam) - 1 ? stat_nam[state] : '?');
#if BITS_PER_LONG == 32
if (state == TASK_RUNNING)
printk(KERN_CONT " running ");
else
printk(KERN_CONT " %08lx ", thread_saved_pc(p));
#else
if (state == TASK_RUNNING)
printk(KERN_CONT " running task ");
else
printk(KERN_CONT " %016lx ", thread_saved_pc(p));
#endif
#ifdef CONFIG_DEBUG_STACK_USAGE
free = stack_not_used(p);
#endif
printk(KERN_CONT "%5lu %5d %6d 0x%08lx\n", free,
task_pid_nr(p), task_pid_nr(p->real_parent),
(unsigned long)task_thread_info(p)->flags);
show_stack(p, NULL);
}
void show_state_filter(unsigned long state_filter)
{
struct task_struct *g, *p;
#if BITS_PER_LONG == 32
printk(KERN_INFO
" task PC stack pid father\n");
#else
printk(KERN_INFO
" task PC stack pid father\n");
#endif
read_lock(&tasklist_lock);
do_each_thread(g, p) {
/*
* reset the NMI-timeout, listing all files on a slow
* console might take a lot of time:
*/
touch_nmi_watchdog();
if (!state_filter || (p->state & state_filter))
sched_show_task(p);
} while_each_thread(g, p);
touch_all_softlockup_watchdogs();
#ifdef CONFIG_SCHED_DEBUG
sysrq_sched_debug_show();
#endif
read_unlock(&tasklist_lock);
/*
* Only show locks if all tasks are dumped:
*/
if (!state_filter)
debug_show_all_locks();
}
void __cpuinit init_idle_bootup_task(struct task_struct *idle)
{
idle->sched_class = &idle_sched_class;
}
/**
* init_idle - set up an idle thread for a given CPU
* @idle: task in question
* @cpu: cpu the idle task belongs to
*
* NOTE: this function does not set the idle thread's NEED_RESCHED
* flag, to make booting more robust.
*/
void __cpuinit init_idle(struct task_struct *idle, int cpu)
{
struct rq *rq = cpu_rq(cpu);
unsigned long flags;
raw_spin_lock_irqsave(&rq->lock, flags);
__sched_fork(idle);
idle->state = TASK_RUNNING;
idle->se.exec_start = sched_clock();
do_set_cpus_allowed(idle, cpumask_of(cpu));
/*
* We're having a chicken and egg problem, even though we are
* holding rq->lock, the cpu isn't yet set to this cpu so the
* lockdep check in task_group() will fail.
*
* Similar case to sched_fork(). / Alternatively we could
* use task_rq_lock() here and obtain the other rq->lock.
*
* Silence PROVE_RCU
*/
rcu_read_lock();
__set_task_cpu(idle, cpu);
rcu_read_unlock();
rq->curr = rq->idle = idle;
#if defined(CONFIG_SMP)
idle->on_cpu = 1;
#endif
raw_spin_unlock_irqrestore(&rq->lock, flags);
/* Set the preempt count _outside_ the spinlocks! */
task_thread_info(idle)->preempt_count = 0;
/*
* The idle tasks have their own, simple scheduling class:
*/
idle->sched_class = &idle_sched_class;
ftrace_graph_init_idle_task(idle, cpu);
}
/*
* In a system that switches off the HZ timer nohz_cpu_mask
* indicates which cpus entered this state. This is used
* in the rcu update to wait only for active cpus. For system
* which do not switch off the HZ timer nohz_cpu_mask should
* always be CPU_BITS_NONE.
*/
cpumask_var_t nohz_cpu_mask;
/*
* 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 int get_update_sysctl_factor(void)
{
unsigned int cpus = min_t(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
}
static inline void sched_init_granularity(void)
{
update_sysctl();
}
#ifdef CONFIG_SMP
void do_set_cpus_allowed(struct task_struct *p, const struct cpumask *new_mask)
{
if (p->sched_class && p->sched_class->set_cpus_allowed)
p->sched_class->set_cpus_allowed(p, new_mask);
else {
cpumask_copy(&p->cpus_allowed, new_mask);
p->rt.nr_cpus_allowed = cpumask_weight(new_mask);
}
}
/*
* This is how migration works:
*
* 1) we invoke migration_cpu_stop() on the target CPU using
* stop_one_cpu().
* 2) stopper starts to run (implicitly forcing the migrated thread
* off the CPU)
* 3) it checks whether the migrated task is still in the wrong runqueue.
* 4) if it's in the wrong runqueue then the migration thread removes
* it and puts it into the right queue.
* 5) stopper completes and stop_one_cpu() returns and the migration
* is done.
*/
/*
* Change a given task's CPU affinity. Migrate the thread to a
* proper CPU and schedule it away if the CPU it's executing on
* is removed from the allowed bitmask.
*
* NOTE: the caller must have a valid reference to the task, the
* task must not exit() & deallocate itself prematurely. The
* call is not atomic; no spinlocks may be held.
*/
int set_cpus_allowed_ptr(struct task_struct *p, const struct cpumask *new_mask)
{
unsigned long flags;
struct rq *rq;
unsigned int dest_cpu;
int ret = 0;
rq = task_rq_lock(p, &flags);
if (cpumask_equal(&p->cpus_allowed, new_mask))
goto out;
if (!cpumask_intersects(new_mask, cpu_active_mask)) {
ret = -EINVAL;
goto out;
}
if (unlikely((p->flags & PF_THREAD_BOUND) && p != current)) {
ret = -EINVAL;
goto out;
}
do_set_cpus_allowed(p, new_mask);
/* Can the task run on the task's current CPU? If so, we're done */
if (cpumask_test_cpu(task_cpu(p), new_mask))
goto out;
dest_cpu = cpumask_any_and(cpu_active_mask, new_mask);
if (p->on_rq) {
struct migration_arg arg = { p, dest_cpu };
/* Need help from migration thread: drop lock and wait. */
task_rq_unlock(rq, p, &flags);
stop_one_cpu(cpu_of(rq), migration_cpu_stop, &arg);
tlb_migrate_finish(p->mm);
return 0;
}
out:
task_rq_unlock(rq, p, &flags);
return ret;
}
EXPORT_SYMBOL_GPL(set_cpus_allowed_ptr);
/*
* Move (not current) task off this cpu, onto dest cpu. We're doing
* this because either it can't run here any more (set_cpus_allowed()
* away from this CPU, or CPU going down), or because we're
* attempting to rebalance this task on exec (sched_exec).
*
* So we race with normal scheduler movements, but that's OK, as long
* as the task is no longer on this CPU.
*
* Returns non-zero if task was successfully migrated.
*/
static int __migrate_task(struct task_struct *p, int src_cpu, int dest_cpu)
{
struct rq *rq_dest, *rq_src;
int ret = 0;
if (unlikely(!cpu_active(dest_cpu)))
return ret;
rq_src = cpu_rq(src_cpu);
rq_dest = cpu_rq(dest_cpu);
raw_spin_lock(&p->pi_lock);
double_rq_lock(rq_src, rq_dest);
/* Already moved. */
if (task_cpu(p) != src_cpu)
goto done;
/* Affinity changed (again). */
if (!cpumask_test_cpu(dest_cpu, &p->cpus_allowed))
goto fail;
/*
* If we're not on a rq, the next wake-up will ensure we're
* placed properly.
*/
if (p->on_rq) {
deactivate_task(rq_src, p, 0);
set_task_cpu(p, dest_cpu);
activate_task(rq_dest, p, 0);
check_preempt_curr(rq_dest, p, 0);
}
done:
ret = 1;
fail:
double_rq_unlock(rq_src, rq_dest);
raw_spin_unlock(&p->pi_lock);
return ret;
}
/*
* migration_cpu_stop - this will be executed by a highprio stopper thread
* and performs thread migration by bumping thread off CPU then
* 'pushing' onto another runqueue.
*/
static int migration_cpu_stop(void *data)
{
struct migration_arg *arg = data;
/*
* The original target cpu might have gone down and we might
* be on another cpu but it doesn't matter.
*/
local_irq_disable();
__migrate_task(arg->task, raw_smp_processor_id(), arg->dest_cpu);
local_irq_enable();
return 0;
}
#ifdef CONFIG_HOTPLUG_CPU
/*
* Ensures that the idle task is using init_mm right before its cpu goes
* offline.
*/
void idle_task_exit(void)
{
struct mm_struct *mm = current->active_mm;
BUG_ON(cpu_online(smp_processor_id()));
if (mm != &init_mm)
switch_mm(mm, &init_mm, current);
mmdrop(mm);
}
/*
* While a dead CPU has no uninterruptible tasks queued at this point,
* it might still have a nonzero ->nr_uninterruptible counter, because
* for performance reasons the counter is not stricly tracking tasks to
* their home CPUs. So we just add the counter to another CPU's counter,
* to keep the global sum constant after CPU-down:
*/
static void migrate_nr_uninterruptible(struct rq *rq_src)
{
struct rq *rq_dest = cpu_rq(cpumask_any(cpu_active_mask));
rq_dest->nr_uninterruptible += rq_src->nr_uninterruptible;
rq_src->nr_uninterruptible = 0;
}
/*
* remove the tasks which were accounted by rq from calc_load_tasks.
*/
static void calc_global_load_remove(struct rq *rq)
{
atomic_long_sub(rq->calc_load_active, &calc_load_tasks);
rq->calc_load_active = 0;
}
/*
* Migrate all tasks from the rq, sleeping tasks will be migrated by
* try_to_wake_up()->select_task_rq().
*
* Called with rq->lock held even though we'er in stop_machine() and
* there's no concurrency possible, we hold the required locks anyway
* because of lock validation efforts.
*/
static void migrate_tasks(unsigned int dead_cpu)
{
struct rq *rq = cpu_rq(dead_cpu);
struct task_struct *next, *stop = rq->stop;
int dest_cpu;
/*
* Fudge the rq selection such that the below task selection loop
* doesn't get stuck on the currently eligible stop task.
*
* We're currently inside stop_machine() and the rq is either stuck
* in the stop_machine_cpu_stop() loop, or we're executing this code,
* either way we should never end up calling schedule() until we're
* done here.
*/
rq->stop = NULL;
for ( ; ; ) {
/*
* There's this thread running, bail when that's the only
* remaining thread.
*/
if (rq->nr_running == 1)
break;
next = pick_next_task(rq);
BUG_ON(!next);
next->sched_class->put_prev_task(rq, next);
/* Find suitable destination for @next, with force if needed. */
dest_cpu = select_fallback_rq(dead_cpu, next);
raw_spin_unlock(&rq->lock);
__migrate_task(next, dead_cpu, dest_cpu);
raw_spin_lock(&rq->lock);
}
rq->stop = stop;
}
#endif /* CONFIG_HOTPLUG_CPU */
#if defined(CONFIG_SCHED_DEBUG) && defined(CONFIG_SYSCTL)
static struct ctl_table sd_ctl_dir[] = {
{
.procname = "sched_domain",
.mode = 0555,
},
{}
};
static struct ctl_table sd_ctl_root[] = {
{
.procname = "kernel",
.mode = 0555,
.child = sd_ctl_dir,
},
{}
};
static struct ctl_table *sd_alloc_ctl_entry(int n)
{
struct ctl_table *entry =
kcalloc(n, sizeof(struct ctl_table), GFP_KERNEL);
return entry;
}
static void sd_free_ctl_entry(struct ctl_table **tablep)
{
struct ctl_table *entry;
/*
* In the intermediate directories, both the child directory and
* procname are dynamically allocated and could fail but the mode
* will always be set. In the lowest directory the names are
* static strings and all have proc handlers.
*/
for (entry = *tablep; entry->mode; entry++) {
if (entry->child)
sd_free_ctl_entry(&entry->child);
if (entry->proc_handler == NULL)
kfree(entry->procname);
}
kfree(*tablep);
*tablep = NULL;
}
static void
set_table_entry(struct ctl_table *entry,
const char *procname, void *data, int maxlen,
mode_t mode, proc_handler *proc_handler)
{
entry->procname = procname;
entry->data = data;
entry->maxlen = maxlen;
entry->mode = mode;
entry->proc_handler = proc_handler;
}
static struct ctl_table *
sd_alloc_ctl_domain_table(struct sched_domain *sd)
{
struct ctl_table *table = sd_alloc_ctl_entry(13);
if (table == NULL)
return NULL;
set_table_entry(&table[0], "min_interval", &sd->min_interval,
sizeof(long), 0644, proc_doulongvec_minmax);
set_table_entry(&table[1], "max_interval", &sd->max_interval,
sizeof(long), 0644, proc_doulongvec_minmax);
set_table_entry(&table[2], "busy_idx", &sd->busy_idx,
sizeof(int), 0644, proc_dointvec_minmax);
set_table_entry(&table[3], "idle_idx", &sd->idle_idx,
sizeof(int), 0644, proc_dointvec_minmax);
set_table_entry(&table[4], "newidle_idx", &sd->newidle_idx,
sizeof(int), 0644, proc_dointvec_minmax);
set_table_entry(&table[5], "wake_idx", &sd->wake_idx,
sizeof(int), 0644, proc_dointvec_minmax);
set_table_entry(&table[6], "forkexec_idx", &sd->forkexec_idx,
sizeof(int), 0644, proc_dointvec_minmax);
set_table_entry(&table[7], "busy_factor", &sd->busy_factor,
sizeof(int), 0644, proc_dointvec_minmax);
set_table_entry(&table[8], "imbalance_pct", &sd->imbalance_pct,
sizeof(int), 0644, proc_dointvec_minmax);
set_table_entry(&table[9], "cache_nice_tries",
&sd->cache_nice_tries,
sizeof(int), 0644, proc_dointvec_minmax);
set_table_entry(&table[10], "flags", &sd->flags,
sizeof(int), 0644, proc_dointvec_minmax);
set_table_entry(&table[11], "name", sd->name,
CORENAME_MAX_SIZE, 0444, proc_dostring);
/* &table[12] is terminator */
return table;
}
static ctl_table *sd_alloc_ctl_cpu_table(int cpu)
{
struct ctl_table *entry, *table;
struct sched_domain *sd;
int domain_num = 0, i;
char buf[32];
for_each_domain(cpu, sd)
domain_num++;
entry = table = sd_alloc_ctl_entry(domain_num + 1);
if (table == NULL)
return NULL;
i = 0;
for_each_domain(cpu, sd) {
snprintf(buf, 32, "domain%d", i);
entry->procname = kstrdup(buf, GFP_KERNEL);
entry->mode = 0555;
entry->child = sd_alloc_ctl_domain_table(sd);
entry++;
i++;
}
return table;
}
static struct ctl_table_header *sd_sysctl_header;
static void register_sched_domain_sysctl(void)
{
int i, cpu_num = num_possible_cpus();
struct ctl_table *entry = sd_alloc_ctl_entry(cpu_num + 1);
char buf[32];
WARN_ON(sd_ctl_dir[0].child);
sd_ctl_dir[0].child = entry;
if (entry == NULL)
return;
for_each_possible_cpu(i) {
snprintf(buf, 32, "cpu%d", i);
entry->procname = kstrdup(buf, GFP_KERNEL);
entry->mode = 0555;
entry->child = sd_alloc_ctl_cpu_table(i);
entry++;
}
WARN_ON(sd_sysctl_header);
sd_sysctl_header = register_sysctl_table(sd_ctl_root);
}
/* may be called multiple times per register */
static void unregister_sched_domain_sysctl(void)
{
if (sd_sysctl_header)
unregister_sysctl_table(sd_sysctl_header);
sd_sysctl_header = NULL;
if (sd_ctl_dir[0].child)
sd_free_ctl_entry(&sd_ctl_dir[0].child);
}
#else
static void register_sched_domain_sysctl(void)
{
}
static void unregister_sched_domain_sysctl(void)
{
}
#endif
static void set_rq_online(struct rq *rq)
{
if (!rq->online) {
const struct sched_class *class;
cpumask_set_cpu(rq->cpu, rq->rd->online);
rq->online = 1;
for_each_class(class) {
if (class->rq_online)
class->rq_online(rq);
}
}
}
static void set_rq_offline(struct rq *rq)
{
if (rq->online) {
const struct sched_class *class;
for_each_class(class) {
if (class->rq_offline)
class->rq_offline(rq);
}
cpumask_clear_cpu(rq->cpu, rq->rd->online);
rq->online = 0;
}
}
/*
* migration_call - callback that gets triggered when a CPU is added.
* Here we can start up the necessary migration thread for the new CPU.
*/
static int __cpuinit
migration_call(struct notifier_block *nfb, unsigned long action, void *hcpu)
{
int cpu = (long)hcpu;
unsigned long flags;
struct rq *rq = cpu_rq(cpu);
switch (action & ~CPU_TASKS_FROZEN) {
case CPU_UP_PREPARE:
rq->calc_load_update = calc_load_update;
break;
case CPU_ONLINE:
/* Update our root-domain */
raw_spin_lock_irqsave(&rq->lock, flags);
if (rq->rd) {
BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span));
set_rq_online(rq);
}
raw_spin_unlock_irqrestore(&rq->lock, flags);
break;
#ifdef CONFIG_HOTPLUG_CPU
case CPU_DYING:
sched_ttwu_pending();
/* Update our root-domain */
raw_spin_lock_irqsave(&rq->lock, flags);
if (rq->rd) {
BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span));
set_rq_offline(rq);
}
migrate_tasks(cpu);
BUG_ON(rq->nr_running != 1); /* the migration thread */
raw_spin_unlock_irqrestore(&rq->lock, flags);
migrate_nr_uninterruptible(rq);
calc_global_load_remove(rq);
break;
#endif
}
update_max_interval();
return NOTIFY_OK;
}
/*
* Register at high priority so that task migration (migrate_all_tasks)
* happens before everything else. This has to be lower priority than
* the notifier in the perf_event subsystem, though.
*/
static struct notifier_block __cpuinitdata migration_notifier = {
.notifier_call = migration_call,
.priority = CPU_PRI_MIGRATION,
};
static int __cpuinit sched_cpu_active(struct notifier_block *nfb,
unsigned long action, void *hcpu)
{
switch (action & ~CPU_TASKS_FROZEN) {
case CPU_ONLINE:
case CPU_DOWN_FAILED:
set_cpu_active((long)hcpu, true);
return NOTIFY_OK;
default:
return NOTIFY_DONE;
}
}
static int __cpuinit sched_cpu_inactive(struct notifier_block *nfb,
unsigned long action, void *hcpu)
{
switch (action & ~CPU_TASKS_FROZEN) {
case CPU_DOWN_PREPARE:
set_cpu_active((long)hcpu, false);
return NOTIFY_OK;
default:
return NOTIFY_DONE;
}
}
static int __init migration_init(void)
{
void *cpu = (void *)(long)smp_processor_id();
int err;
/* Initialize migration for the boot CPU */
err = migration_call(&migration_notifier, CPU_UP_PREPARE, cpu);
BUG_ON(err == NOTIFY_BAD);
migration_call(&migration_notifier, CPU_ONLINE, cpu);
register_cpu_notifier(&migration_notifier);
/* Register cpu active notifiers */
cpu_notifier(sched_cpu_active, CPU_PRI_SCHED_ACTIVE);
cpu_notifier(sched_cpu_inactive, CPU_PRI_SCHED_INACTIVE);
return 0;
}
early_initcall(migration_init);
#endif
#ifdef CONFIG_SMP
static cpumask_var_t sched_domains_tmpmask; /* sched_domains_mutex */
#ifdef CONFIG_SCHED_DEBUG
static __read_mostly int sched_domain_debug_enabled;
static int __init sched_domain_debug_setup(char *str)
{
sched_domain_debug_enabled = 1;
return 0;
}
early_param("sched_debug", sched_domain_debug_setup);
static int sched_domain_debug_one(struct sched_domain *sd, int cpu, int level,
struct cpumask *groupmask)
{
struct sched_group *group = sd->groups;
char str[256];
cpulist_scnprintf(str, sizeof(str), sched_domain_span(sd));
cpumask_clear(groupmask);
printk(KERN_DEBUG "%*s domain %d: ", level, "", level);
if (!(sd->flags & SD_LOAD_BALANCE)) {
printk("does not load-balance\n");
if (sd->parent)
printk(KERN_ERR "ERROR: !SD_LOAD_BALANCE domain"
" has parent");
return -1;
}
printk(KERN_CONT "span %s level %s\n", str, sd->name);
if (!cpumask_test_cpu(cpu, sched_domain_span(sd))) {
printk(KERN_ERR "ERROR: domain->span does not contain "
"CPU%d\n", cpu);
}
if (!cpumask_test_cpu(cpu, sched_group_cpus(group))) {
printk(KERN_ERR "ERROR: domain->groups does not contain"
" CPU%d\n", cpu);
}
printk(KERN_DEBUG "%*s groups:", level + 1, "");
do {
if (!group) {
printk("\n");
printk(KERN_ERR "ERROR: group is NULL\n");
break;
}
if (!group->sgp->power) {
printk(KERN_CONT "\n");
printk(KERN_ERR "ERROR: domain->cpu_power not "
"set\n");
break;
}
if (!cpumask_weight(sched_group_cpus(group))) {
printk(KERN_CONT "\n");
printk(KERN_ERR "ERROR: empty group\n");
break;
}
if (cpumask_intersects(groupmask, sched_group_cpus(group))) {
printk(KERN_CONT "\n");
printk(KERN_ERR "ERROR: repeated CPUs\n");
break;
}
cpumask_or(groupmask, groupmask, sched_group_cpus(group));
cpulist_scnprintf(str, sizeof(str), sched_group_cpus(group));
printk(KERN_CONT " %s", str);
if (group->sgp->power != SCHED_POWER_SCALE) {
printk(KERN_CONT " (cpu_power = %d)",
group->sgp->power);
}
group = group->next;
} while (group != sd->groups);
printk(KERN_CONT "\n");
if (!cpumask_equal(sched_domain_span(sd), groupmask))
printk(KERN_ERR "ERROR: groups don't span domain->span\n");
if (sd->parent &&
!cpumask_subset(groupmask, sched_domain_span(sd->parent)))
printk(KERN_ERR "ERROR: parent span is not a superset "
"of domain->span\n");
return 0;
}
static void sched_domain_debug(struct sched_domain *sd, int cpu)
{
int level = 0;
if (!sched_domain_debug_enabled)
return;
if (!sd) {
printk(KERN_DEBUG "CPU%d attaching NULL sched-domain.\n", cpu);
return;
}
printk(KERN_DEBUG "CPU%d attaching sched-domain:\n", cpu);
for (;;) {
if (sched_domain_debug_one(sd, cpu, level, sched_domains_tmpmask))
break;
level++;
sd = sd->parent;
if (!sd)
break;
}
}
#else /* !CONFIG_SCHED_DEBUG */
# define sched_domain_debug(sd, cpu) do { } while (0)
#endif /* CONFIG_SCHED_DEBUG */
static int sd_degenerate(struct sched_domain *sd)
{
if (cpumask_weight(sched_domain_span(sd)) == 1)
return 1;
/* Following flags need at least 2 groups */
if (sd->flags & (SD_LOAD_BALANCE |
SD_BALANCE_NEWIDLE |
SD_BALANCE_FORK |
SD_BALANCE_EXEC |
SD_SHARE_CPUPOWER |
SD_SHARE_PKG_RESOURCES)) {
if (sd->groups != sd->groups->next)
return 0;
}
/* Following flags don't use groups */
if (sd->flags & (SD_WAKE_AFFINE))
return 0;
return 1;
}
static int
sd_parent_degenerate(struct sched_domain *sd, struct sched_domain *parent)
{
unsigned long cflags = sd->flags, pflags = parent->flags;
if (sd_degenerate(parent))
return 1;
if (!cpumask_equal(sched_domain_span(sd), sched_domain_span(parent)))
return 0;
/* Flags needing groups don't count if only 1 group in parent */
if (parent->groups == parent->groups->next) {
pflags &= ~(SD_LOAD_BALANCE |
SD_BALANCE_NEWIDLE |
SD_BALANCE_FORK |
SD_BALANCE_EXEC |
SD_SHARE_CPUPOWER |
SD_SHARE_PKG_RESOURCES);
if (nr_node_ids == 1)
pflags &= ~SD_SERIALIZE;
}
if (~cflags & pflags)
return 0;
return 1;
}
static void free_rootdomain(struct rcu_head *rcu)
{
struct root_domain *rd = container_of(rcu, struct root_domain, rcu);
cpupri_cleanup(&rd->cpupri);
free_cpumask_var(rd->rto_mask);
free_cpumask_var(rd->online);
free_cpumask_var(rd->span);
kfree(rd);
}
static void rq_attach_root(struct rq *rq, struct root_domain *rd)
{
struct root_domain *old_rd = NULL;
unsigned long flags;
raw_spin_lock_irqsave(&rq->lock, flags);
if (rq->rd) {
old_rd = rq->rd;
if (cpumask_test_cpu(rq->cpu, old_rd->online))
set_rq_offline(rq);
cpumask_clear_cpu(rq->cpu, old_rd->span);
/*
* If we dont want to free the old_rt yet then
* set old_rd to NULL to skip the freeing later
* in this function:
*/
if (!atomic_dec_and_test(&old_rd->refcount))
old_rd = NULL;
}
atomic_inc(&rd->refcount);
rq->rd = rd;
cpumask_set_cpu(rq->cpu, rd->span);
if (cpumask_test_cpu(rq->cpu, cpu_active_mask))
set_rq_online(rq);
raw_spin_unlock_irqrestore(&rq->lock, flags);
if (old_rd)
call_rcu_sched(&old_rd->rcu, free_rootdomain);
}
static int init_rootdomain(struct root_domain *rd)
{
memset(rd, 0, sizeof(*rd));
if (!alloc_cpumask_var(&rd->span, GFP_KERNEL))
goto out;
if (!alloc_cpumask_var(&rd->online, GFP_KERNEL))
goto free_span;
if (!alloc_cpumask_var(&rd->rto_mask, GFP_KERNEL))
goto free_online;
if (cpupri_init(&rd->cpupri) != 0)
goto free_rto_mask;
return 0;
free_rto_mask:
free_cpumask_var(rd->rto_mask);
free_online:
free_cpumask_var(rd->online);
free_span:
free_cpumask_var(rd->span);
out:
return -ENOMEM;
}
static void init_defrootdomain(void)
{
init_rootdomain(&def_root_domain);
atomic_set(&def_root_domain.refcount, 1);
}
static struct root_domain *alloc_rootdomain(void)
{
struct root_domain *rd;
rd = kmalloc(sizeof(*rd), GFP_KERNEL);
if (!rd)
return NULL;
if (init_rootdomain(rd) != 0) {
kfree(rd);
return NULL;
}
return rd;
}
static void free_sched_groups(struct sched_group *sg, int free_sgp)
{
struct sched_group *tmp, *first;
if (!sg)
return;
first = sg;
do {
tmp = sg->next;
if (free_sgp && atomic_dec_and_test(&sg->sgp->ref))
kfree(sg->sgp);
kfree(sg);
sg = tmp;
} while (sg != first);
}
static void free_sched_domain(struct rcu_head *rcu)
{
struct sched_domain *sd = container_of(rcu, struct sched_domain, rcu);
/*
* If its an overlapping domain it has private groups, iterate and
* nuke them all.
*/
if (sd->flags & SD_OVERLAP) {
free_sched_groups(sd->groups, 1);
} else if (atomic_dec_and_test(&sd->groups->ref)) {
kfree(sd->groups->sgp);
kfree(sd->groups);
}
kfree(sd);
}
static void destroy_sched_domain(struct sched_domain *sd, int cpu)
{
call_rcu(&sd->rcu, free_sched_domain);
}
static void destroy_sched_domains(struct sched_domain *sd, int cpu)
{
for (; sd; sd = sd->parent)
destroy_sched_domain(sd, cpu);
}
/*
* Attach the domain 'sd' to 'cpu' as its base domain. Callers must
* hold the hotplug lock.
*/
static void
cpu_attach_domain(struct sched_domain *sd, struct root_domain *rd, int cpu)
{
struct rq *rq = cpu_rq(cpu);
struct sched_domain *tmp;
/* Remove the sched domains which do not contribute to scheduling. */
for (tmp = sd; tmp; ) {
struct sched_domain *parent = tmp->parent;
if (!parent)
break;
if (sd_parent_degenerate(tmp, parent)) {
tmp->parent = parent->parent;
if (parent->parent)
parent->parent->child = tmp;
destroy_sched_domain(parent, cpu);
} else
tmp = tmp->parent;
}
if (sd && sd_degenerate(sd)) {
tmp = sd;
sd = sd->parent;
destroy_sched_domain(tmp, cpu);
if (sd)
sd->child = NULL;
}
sched_domain_debug(sd, cpu);
rq_attach_root(rq, rd);
tmp = rq->sd;
rcu_assign_pointer(rq->sd, sd);
destroy_sched_domains(tmp, cpu);
}
/* cpus with isolated domains */
static cpumask_var_t cpu_isolated_map;
/* Setup the mask of cpus configured for isolated domains */
static int __init isolated_cpu_setup(char *str)
{
alloc_bootmem_cpumask_var(&cpu_isolated_map);
cpulist_parse(str, cpu_isolated_map);
return 1;
}
__setup("isolcpus=", isolated_cpu_setup);
#define SD_NODES_PER_DOMAIN 16
#ifdef CONFIG_NUMA
/**
* find_next_best_node - find the next node to include in a sched_domain
* @node: node whose sched_domain we're building
* @used_nodes: nodes already in the sched_domain
*
* Find the next node to include in a given scheduling domain. Simply
* finds the closest node not already in the @used_nodes map.
*
* Should use nodemask_t.
*/
static int find_next_best_node(int node, nodemask_t *used_nodes)
{
int i, n, val, min_val, best_node = -1;
min_val = INT_MAX;
for (i = 0; i < nr_node_ids; i++) {
/* Start at @node */
n = (node + i) % nr_node_ids;
if (!nr_cpus_node(n))
continue;
/* Skip already used nodes */
if (node_isset(n, *used_nodes))
continue;
/* Simple min distance search */
val = node_distance(node, n);
if (val < min_val) {
min_val = val;
best_node = n;
}
}
if (best_node != -1)
node_set(best_node, *used_nodes);
return best_node;
}
/**
* sched_domain_node_span - get a cpumask for a node's sched_domain
* @node: node whose cpumask we're constructing
* @span: resulting cpumask
*
* Given a node, construct a good cpumask for its sched_domain to span. It
* should be one that prevents unnecessary balancing, but also spreads tasks
* out optimally.
*/
static void sched_domain_node_span(int node, struct cpumask *span)
{
nodemask_t used_nodes;
int i;
cpumask_clear(span);
nodes_clear(used_nodes);
cpumask_or(span, span, cpumask_of_node(node));
node_set(node, used_nodes);
for (i = 1; i < SD_NODES_PER_DOMAIN; i++) {
int next_node = find_next_best_node(node, &used_nodes);
if (next_node < 0)
break;
cpumask_or(span, span, cpumask_of_node(next_node));
}
}
static const struct cpumask *cpu_node_mask(int cpu)
{
lockdep_assert_held(&sched_domains_mutex);
sched_domain_node_span(cpu_to_node(cpu), sched_domains_tmpmask);
return sched_domains_tmpmask;
}
static const struct cpumask *cpu_allnodes_mask(int cpu)
{
return cpu_possible_mask;
}
#endif /* CONFIG_NUMA */
static const struct cpumask *cpu_cpu_mask(int cpu)
{
return cpumask_of_node(cpu_to_node(cpu));
}
int sched_smt_power_savings = 0, sched_mc_power_savings = 0;
struct sd_data {
struct sched_domain **__percpu sd;
struct sched_group **__percpu sg;
struct sched_group_power **__percpu sgp;
};
struct s_data {
struct sched_domain ** __percpu sd;
struct root_domain *rd;
};
enum s_alloc {
sa_rootdomain,
sa_sd,
sa_sd_storage,
sa_none,
};
struct sched_domain_topology_level;
typedef struct sched_domain *(*sched_domain_init_f)(struct sched_domain_topology_level *tl, int cpu);
typedef const struct cpumask *(*sched_domain_mask_f)(int cpu);
#define SDTL_OVERLAP 0x01
struct sched_domain_topology_level {
sched_domain_init_f init;
sched_domain_mask_f mask;
int flags;
struct sd_data data;
};
static int
build_overlap_sched_groups(struct sched_domain *sd, int cpu)
{
struct sched_group *first = NULL, *last = NULL, *groups = NULL, *sg;
const struct cpumask *span = sched_domain_span(sd);
struct cpumask *covered = sched_domains_tmpmask;
struct sd_data *sdd = sd->private;
struct sched_domain *child;
int i;
cpumask_clear(covered);
for_each_cpu(i, span) {
struct cpumask *sg_span;
if (cpumask_test_cpu(i, covered))
continue;
sg = kzalloc_node(sizeof(struct sched_group) + cpumask_size(),
GFP_KERNEL, cpu_to_node(i));
if (!sg)
goto fail;
sg_span = sched_group_cpus(sg);
child = *per_cpu_ptr(sdd->sd, i);
if (child->child) {
child = child->child;
cpumask_copy(sg_span, sched_domain_span(child));
} else
cpumask_set_cpu(i, sg_span);
cpumask_or(covered, covered, sg_span);
sg->sgp = *per_cpu_ptr(sdd->sgp, cpumask_first(sg_span));
atomic_inc(&sg->sgp->ref);
if (cpumask_test_cpu(cpu, sg_span))
groups = sg;
if (!first)
first = sg;
if (last)
last->next = sg;
last = sg;
last->next = first;
}
sd->groups = groups;
return 0;
fail:
free_sched_groups(first, 0);
return -ENOMEM;
}
static int get_group(int cpu, struct sd_data *sdd, struct sched_group **sg)
{
struct sched_domain *sd = *per_cpu_ptr(sdd->sd, cpu);
struct sched_domain *child = sd->child;
if (child)
cpu = cpumask_first(sched_domain_span(child));
if (sg) {
*sg = *per_cpu_ptr(sdd->sg, cpu);
(*sg)->sgp = *per_cpu_ptr(sdd->sgp, cpu);
atomic_set(&(*sg)->sgp->ref, 1); /* for claim_allocations */
}
return cpu;
}
/*
* build_sched_groups will build a circular linked list of the groups
* covered by the given span, and will set each group's ->cpumask correctly,
* and ->cpu_power to 0.
*
* Assumes the sched_domain tree is fully constructed
*/
static int
build_sched_groups(struct sched_domain *sd, int cpu)
{
struct sched_group *first = NULL, *last = NULL;
struct sd_data *sdd = sd->private;
const struct cpumask *span = sched_domain_span(sd);
struct cpumask *covered;
int i;
get_group(cpu, sdd, &sd->groups);
atomic_inc(&sd->groups->ref);
if (cpu != cpumask_first(sched_domain_span(sd)))
return 0;
lockdep_assert_held(&sched_domains_mutex);
covered = sched_domains_tmpmask;
cpumask_clear(covered);
for_each_cpu(i, span) {
struct sched_group *sg;
int group = get_group(i, sdd, &sg);
int j;
if (cpumask_test_cpu(i, covered))
continue;
cpumask_clear(sched_group_cpus(sg));
sg->sgp->power = 0;
for_each_cpu(j, span) {
if (get_group(j, sdd, NULL) != group)
continue;
cpumask_set_cpu(j, covered);
cpumask_set_cpu(j, sched_group_cpus(sg));
}
if (!first)
first = sg;
if (last)
last->next = sg;
last = sg;
}
last->next = first;
return 0;
}
/*
* Initialize sched groups cpu_power.
*
* cpu_power indicates the capacity of sched group, which is used while
* distributing the load between different sched groups in a sched domain.
* Typically cpu_power for all the groups in a sched domain will be same unless
* there are asymmetries in the topology. If there are asymmetries, group
* having more cpu_power will pickup more load compared to the group having
* less cpu_power.
*/
static void init_sched_groups_power(int cpu, struct sched_domain *sd)
{
struct sched_group *sg = sd->groups;
WARN_ON(!sd || !sg);
do {
sg->group_weight = cpumask_weight(sched_group_cpus(sg));
sg = sg->next;
} while (sg != sd->groups);
if (cpu != group_first_cpu(sg))
return;
update_group_power(sd, cpu);
}
/*
* Initializers for schedule domains
* Non-inlined to reduce accumulated stack pressure in build_sched_domains()
*/
#ifdef CONFIG_SCHED_DEBUG
# define SD_INIT_NAME(sd, type) sd->name = #type
#else
# define SD_INIT_NAME(sd, type) do { } while (0)
#endif
#define SD_INIT_FUNC(type) \
static noinline struct sched_domain * \
sd_init_##type(struct sched_domain_topology_level *tl, int cpu) \
{ \
struct sched_domain *sd = *per_cpu_ptr(tl->data.sd, cpu); \
*sd = SD_##type##_INIT; \
SD_INIT_NAME(sd, type); \
sd->private = &tl->data; \
return sd; \
}
SD_INIT_FUNC(CPU)
#ifdef CONFIG_NUMA
SD_INIT_FUNC(ALLNODES)
SD_INIT_FUNC(NODE)
#endif
#ifdef CONFIG_SCHED_SMT
SD_INIT_FUNC(SIBLING)
#endif
#ifdef CONFIG_SCHED_MC
SD_INIT_FUNC(MC)
#endif
#ifdef CONFIG_SCHED_BOOK
SD_INIT_FUNC(BOOK)
#endif
static int default_relax_domain_level = -1;
int sched_domain_level_max;
static int __init setup_relax_domain_level(char *str)
{
unsigned long val;
val = simple_strtoul(str, NULL, 0);
if (val < sched_domain_level_max)
default_relax_domain_level = val;
return 1;
}
__setup("relax_domain_level=", setup_relax_domain_level);
static void set_domain_attribute(struct sched_domain *sd,
struct sched_domain_attr *attr)
{
int request;
if (!attr || attr->relax_domain_level < 0) {
if (default_relax_domain_level < 0)
return;
else
request = default_relax_domain_level;
} else
request = attr->relax_domain_level;
if (request < sd->level) {
/* turn off idle balance on this domain */
sd->flags &= ~(SD_BALANCE_WAKE|SD_BALANCE_NEWIDLE);
} else {
/* turn on idle balance on this domain */
sd->flags |= (SD_BALANCE_WAKE|SD_BALANCE_NEWIDLE);
}
}
static void __sdt_free(const struct cpumask *cpu_map);
static int __sdt_alloc(const struct cpumask *cpu_map);
static void __free_domain_allocs(struct s_data *d, enum s_alloc what,
const struct cpumask *cpu_map)
{
switch (what) {
case sa_rootdomain:
if (!atomic_read(&d->rd->refcount))
free_rootdomain(&d->rd->rcu); /* fall through */
case sa_sd:
free_percpu(d->sd); /* fall through */
case sa_sd_storage:
__sdt_free(cpu_map); /* fall through */
case sa_none:
break;
}
}
static enum s_alloc __visit_domain_allocation_hell(struct s_data *d,
const struct cpumask *cpu_map)
{
memset(d, 0, sizeof(*d));
if (__sdt_alloc(cpu_map))
return sa_sd_storage;
d->sd = alloc_percpu(struct sched_domain *);
if (!d->sd)
return sa_sd_storage;
d->rd = alloc_rootdomain();
if (!d->rd)
return sa_sd;
return sa_rootdomain;
}
/*
* NULL the sd_data elements we've used to build the sched_domain and
* sched_group structure so that the subsequent __free_domain_allocs()
* will not free the data we're using.
*/
static void claim_allocations(int cpu, struct sched_domain *sd)
{
struct sd_data *sdd = sd->private;
WARN_ON_ONCE(*per_cpu_ptr(sdd->sd, cpu) != sd);
*per_cpu_ptr(sdd->sd, cpu) = NULL;
if (atomic_read(&(*per_cpu_ptr(sdd->sg, cpu))->ref))
*per_cpu_ptr(sdd->sg, cpu) = NULL;
if (atomic_read(&(*per_cpu_ptr(sdd->sgp, cpu))->ref))
*per_cpu_ptr(sdd->sgp, cpu) = NULL;
}
#ifdef CONFIG_SCHED_SMT
static const struct cpumask *cpu_smt_mask(int cpu)
{
return topology_thread_cpumask(cpu);
}
#endif
/*
* Topology list, bottom-up.
*/
static struct sched_domain_topology_level default_topology[] = {
#ifdef CONFIG_SCHED_SMT
{ sd_init_SIBLING, cpu_smt_mask, },
#endif
#ifdef CONFIG_SCHED_MC
{ sd_init_MC, cpu_coregroup_mask, },
#endif
#ifdef CONFIG_SCHED_BOOK
{ sd_init_BOOK, cpu_book_mask, },
#endif
{ sd_init_CPU, cpu_cpu_mask, },
#ifdef CONFIG_NUMA
{ sd_init_NODE, cpu_node_mask, SDTL_OVERLAP, },
{ sd_init_ALLNODES, cpu_allnodes_mask, },
#endif
{ NULL, },
};
static struct sched_domain_topology_level *sched_domain_topology = default_topology;
static int __sdt_alloc(const struct cpumask *cpu_map)
{
struct sched_domain_topology_level *tl;
int j;
for (tl = sched_domain_topology; tl->init; tl++) {
struct sd_data *sdd = &tl->data;
sdd->sd = alloc_percpu(struct sched_domain *);
if (!sdd->sd)
return -ENOMEM;
sdd->sg = alloc_percpu(struct sched_group *);
if (!sdd->sg)
return -ENOMEM;
sdd->sgp = alloc_percpu(struct sched_group_power *);
if (!sdd->sgp)
return -ENOMEM;
for_each_cpu(j, cpu_map) {
struct sched_domain *sd;
struct sched_group *sg;
struct sched_group_power *sgp;
sd = kzalloc_node(sizeof(struct sched_domain) + cpumask_size(),
GFP_KERNEL, cpu_to_node(j));
if (!sd)
return -ENOMEM;
*per_cpu_ptr(sdd->sd, j) = sd;
sg = kzalloc_node(sizeof(struct sched_group) + cpumask_size(),
GFP_KERNEL, cpu_to_node(j));
if (!sg)
return -ENOMEM;
*per_cpu_ptr(sdd->sg, j) = sg;
sgp = kzalloc_node(sizeof(struct sched_group_power),
GFP_KERNEL, cpu_to_node(j));
if (!sgp)
return -ENOMEM;
*per_cpu_ptr(sdd->sgp, j) = sgp;
}
}
return 0;
}
static void __sdt_free(const struct cpumask *cpu_map)
{
struct sched_domain_topology_level *tl;
int j;
for (tl = sched_domain_topology; tl->init; tl++) {
struct sd_data *sdd = &tl->data;
for_each_cpu(j, cpu_map) {
struct sched_domain *sd = *per_cpu_ptr(sdd->sd, j);
if (sd && (sd->flags & SD_OVERLAP))
free_sched_groups(sd->groups, 0);
kfree(*per_cpu_ptr(sdd->sg, j));
kfree(*per_cpu_ptr(sdd->sgp, j));
}
free_percpu(sdd->sd);
free_percpu(sdd->sg);
free_percpu(sdd->sgp);
}
}
struct sched_domain *build_sched_domain(struct sched_domain_topology_level *tl,
struct s_data *d, const struct cpumask *cpu_map,
struct sched_domain_attr *attr, struct sched_domain *child,
int cpu)
{
struct sched_domain *sd = tl->init(tl, cpu);
if (!sd)
return child;
set_domain_attribute(sd, attr);
cpumask_and(sched_domain_span(sd), cpu_map, tl->mask(cpu));
if (child) {
sd->level = child->level + 1;
sched_domain_level_max = max(sched_domain_level_max, sd->level);
child->parent = sd;
}
sd->child = child;
return sd;
}
/*
* Build sched domains for a given set of cpus and attach the sched domains
* to the individual cpus
*/
static int build_sched_domains(const struct cpumask *cpu_map,
struct sched_domain_attr *attr)
{
enum s_alloc alloc_state = sa_none;
struct sched_domain *sd;
struct s_data d;
int i, ret = -ENOMEM;
alloc_state = __visit_domain_allocation_hell(&d, cpu_map);
if (alloc_state != sa_rootdomain)
goto error;
/* Set up domains for cpus specified by the cpu_map. */
for_each_cpu(i, cpu_map) {
struct sched_domain_topology_level *tl;
sd = NULL;
for (tl = sched_domain_topology; tl->init; tl++) {
sd = build_sched_domain(tl, &d, cpu_map, attr, sd, i);
if (tl->flags & SDTL_OVERLAP || sched_feat(FORCE_SD_OVERLAP))
sd->flags |= SD_OVERLAP;
if (cpumask_equal(cpu_map, sched_domain_span(sd)))
break;
}
while (sd->child)
sd = sd->child;
*per_cpu_ptr(d.sd, i) = sd;
}
/* Build the groups for the domains */
for_each_cpu(i, cpu_map) {
for (sd = *per_cpu_ptr(d.sd, i); sd; sd = sd->parent) {
sd->span_weight = cpumask_weight(sched_domain_span(sd));
if (sd->flags & SD_OVERLAP) {
if (build_overlap_sched_groups(sd, i))
goto error;
} else {
if (build_sched_groups(sd, i))
goto error;
}
}
}
/* Calculate CPU power for physical packages and nodes */
for (i = nr_cpumask_bits-1; i >= 0; i--) {
if (!cpumask_test_cpu(i, cpu_map))
continue;
for (sd = *per_cpu_ptr(d.sd, i); sd; sd = sd->parent) {
claim_allocations(i, sd);
init_sched_groups_power(i, sd);
}
}
/* Attach the domains */
rcu_read_lock();
for_each_cpu(i, cpu_map) {
sd = *per_cpu_ptr(d.sd, i);
cpu_attach_domain(sd, d.rd, i);
}
rcu_read_unlock();
ret = 0;
error:
__free_domain_allocs(&d, alloc_state, cpu_map);
return ret;
}
static cpumask_var_t *doms_cur; /* current sched domains */
static int ndoms_cur; /* number of sched domains in 'doms_cur' */
static struct sched_domain_attr *dattr_cur;
/* attribues of custom domains in 'doms_cur' */
/*
* Special case: If a kmalloc of a doms_cur partition (array of
* cpumask) fails, then fallback to a single sched domain,
* as determined by the single cpumask fallback_doms.
*/
static cpumask_var_t fallback_doms;
/*
* arch_update_cpu_topology lets virtualized architectures update the
* cpu core maps. It is supposed to return 1 if the topology changed
* or 0 if it stayed the same.
*/
int __attribute__((weak)) arch_update_cpu_topology(void)
{
return 0;
}
cpumask_var_t *alloc_sched_domains(unsigned int ndoms)
{
int i;
cpumask_var_t *doms;
doms = kmalloc(sizeof(*doms) * ndoms, GFP_KERNEL);
if (!doms)
return NULL;
for (i = 0; i < ndoms; i++) {
if (!alloc_cpumask_var(&doms[i], GFP_KERNEL)) {
free_sched_domains(doms, i);
return NULL;
}
}
return doms;
}
void free_sched_domains(cpumask_var_t doms[], unsigned int ndoms)
{
unsigned int i;
for (i = 0; i < ndoms; i++)
free_cpumask_var(doms[i]);
kfree(doms);
}
/*
* Set up scheduler domains and groups. Callers must hold the hotplug lock.
* For now this just excludes isolated cpus, but could be used to
* exclude other special cases in the future.
*/
static int init_sched_domains(const struct cpumask *cpu_map)
{
int err;
arch_update_cpu_topology();
ndoms_cur = 1;
doms_cur = alloc_sched_domains(ndoms_cur);
if (!doms_cur)
doms_cur = &fallback_doms;
cpumask_andnot(doms_cur[0], cpu_map, cpu_isolated_map);
dattr_cur = NULL;
err = build_sched_domains(doms_cur[0], NULL);
register_sched_domain_sysctl();
return err;
}
/*
* Detach sched domains from a group of cpus specified in cpu_map
* These cpus will now be attached to the NULL domain
*/
static void detach_destroy_domains(const struct cpumask *cpu_map)
{
int i;
rcu_read_lock();
for_each_cpu(i, cpu_map)
cpu_attach_domain(NULL, &def_root_domain, i);
rcu_read_unlock();
}
/* handle null as "default" */
static int dattrs_equal(struct sched_domain_attr *cur, int idx_cur,
struct sched_domain_attr *new, int idx_new)
{
struct sched_domain_attr tmp;
/* fast path */
if (!new && !cur)
return 1;
tmp = SD_ATTR_INIT;
return !memcmp(cur ? (cur + idx_cur) : &tmp,
new ? (new + idx_new) : &tmp,
sizeof(struct sched_domain_attr));
}
/*
* Partition sched domains as specified by the 'ndoms_new'
* cpumasks in the array doms_new[] of cpumasks. This compares
* doms_new[] to the current sched domain partitioning, doms_cur[].
* It destroys each deleted domain and builds each new domain.
*
* 'doms_new' is an array of cpumask_var_t's of length 'ndoms_new'.
* The masks don't intersect (don't overlap.) We should setup one
* sched domain for each mask. CPUs not in any of the cpumasks will
* not be load balanced. If the same cpumask appears both in the
* current 'doms_cur' domains and in the new 'doms_new', we can leave
* it as it is.
*
* The passed in 'doms_new' should be allocated using
* alloc_sched_domains. This routine takes ownership of it and will
* free_sched_domains it when done with it. If the caller failed the
* alloc call, then it can pass in doms_new == NULL && ndoms_new == 1,
* and partition_sched_domains() will fallback to the single partition
* 'fallback_doms', it also forces the domains to be rebuilt.
*
* If doms_new == NULL it will be replaced with cpu_online_mask.
* ndoms_new == 0 is a special case for destroying existing domains,
* and it will not create the default domain.
*
* Call with hotplug lock held
*/
void partition_sched_domains(int ndoms_new, cpumask_var_t doms_new[],
struct sched_domain_attr *dattr_new)
{
int i, j, n;
int new_topology;
mutex_lock(&sched_domains_mutex);
/* always unregister in case we don't destroy any domains */
unregister_sched_domain_sysctl();
/* Let architecture update cpu core mappings. */
new_topology = arch_update_cpu_topology();
n = doms_new ? ndoms_new : 0;
/* Destroy deleted domains */
for (i = 0; i < ndoms_cur; i++) {
for (j = 0; j < n && !new_topology; j++) {
if (cpumask_equal(doms_cur[i], doms_new[j])
&& dattrs_equal(dattr_cur, i, dattr_new, j))
goto match1;
}
/* no match - a current sched domain not in new doms_new[] */
detach_destroy_domains(doms_cur[i]);
match1:
;
}
if (doms_new == NULL) {
ndoms_cur = 0;
doms_new = &fallback_doms;
cpumask_andnot(doms_new[0], cpu_active_mask, cpu_isolated_map);
WARN_ON_ONCE(dattr_new);
}
/* Build new domains */
for (i = 0; i < ndoms_new; i++) {
for (j = 0; j < ndoms_cur && !new_topology; j++) {
if (cpumask_equal(doms_new[i], doms_cur[j])
&& dattrs_equal(dattr_new, i, dattr_cur, j))
goto match2;
}
/* no match - add a new doms_new */
build_sched_domains(doms_new[i], dattr_new ? dattr_new + i : NULL);
match2:
;
}
/* Remember the new sched domains */
if (doms_cur != &fallback_doms)
free_sched_domains(doms_cur, ndoms_cur);
kfree(dattr_cur); /* kfree(NULL) is safe */
doms_cur = doms_new;
dattr_cur = dattr_new;
ndoms_cur = ndoms_new;
register_sched_domain_sysctl();
mutex_unlock(&sched_domains_mutex);
}
#if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
static void reinit_sched_domains(void)
{
get_online_cpus();
/* Destroy domains first to force the rebuild */
partition_sched_domains(0, NULL, NULL);
rebuild_sched_domains();
put_online_cpus();
}
static ssize_t sched_power_savings_store(const char *buf, size_t count, int smt)
{
unsigned int level = 0;
if (sscanf(buf, "%u", &level) != 1)
return -EINVAL;
/*
* level is always be positive so don't check for
* level < POWERSAVINGS_BALANCE_NONE which is 0
* What happens on 0 or 1 byte write,
* need to check for count as well?
*/
if (level >= MAX_POWERSAVINGS_BALANCE_LEVELS)
return -EINVAL;
if (smt)
sched_smt_power_savings = level;
else
sched_mc_power_savings = level;
reinit_sched_domains();
return count;
}
#ifdef CONFIG_SCHED_MC
static ssize_t sched_mc_power_savings_show(struct sysdev_class *class,
struct sysdev_class_attribute *attr,
char *page)
{
return sprintf(page, "%u\n", sched_mc_power_savings);
}
static ssize_t sched_mc_power_savings_store(struct sysdev_class *class,
struct sysdev_class_attribute *attr,
const char *buf, size_t count)
{
return sched_power_savings_store(buf, count, 0);
}
static SYSDEV_CLASS_ATTR(sched_mc_power_savings, 0644,
sched_mc_power_savings_show,
sched_mc_power_savings_store);
#endif
#ifdef CONFIG_SCHED_SMT
static ssize_t sched_smt_power_savings_show(struct sysdev_class *dev,
struct sysdev_class_attribute *attr,
char *page)
{
return sprintf(page, "%u\n", sched_smt_power_savings);
}
static ssize_t sched_smt_power_savings_store(struct sysdev_class *dev,
struct sysdev_class_attribute *attr,
const char *buf, size_t count)
{
return sched_power_savings_store(buf, count, 1);
}
static SYSDEV_CLASS_ATTR(sched_smt_power_savings, 0644,
sched_smt_power_savings_show,
sched_smt_power_savings_store);
#endif
int __init sched_create_sysfs_power_savings_entries(struct sysdev_class *cls)
{
int err = 0;
#ifdef CONFIG_SCHED_SMT
if (smt_capable())
err = sysfs_create_file(&cls->kset.kobj,
&attr_sched_smt_power_savings.attr);
#endif
#ifdef CONFIG_SCHED_MC
if (!err && mc_capable())
err = sysfs_create_file(&cls->kset.kobj,
&attr_sched_mc_power_savings.attr);
#endif
return err;
}
#endif /* CONFIG_SCHED_MC || CONFIG_SCHED_SMT */
/*
* Update cpusets according to cpu_active mask. If cpusets are
* disabled, cpuset_update_active_cpus() becomes a simple wrapper
* around partition_sched_domains().
*/
static int cpuset_cpu_active(struct notifier_block *nfb, unsigned long action,
void *hcpu)
{
switch (action & ~CPU_TASKS_FROZEN) {
case CPU_ONLINE:
case CPU_DOWN_FAILED:
cpuset_update_active_cpus();
return NOTIFY_OK;
default:
return NOTIFY_DONE;
}
}
static int cpuset_cpu_inactive(struct notifier_block *nfb, unsigned long action,
void *hcpu)
{
switch (action & ~CPU_TASKS_FROZEN) {
case CPU_DOWN_PREPARE:
cpuset_update_active_cpus();
return NOTIFY_OK;
default:
return NOTIFY_DONE;
}
}
static int update_runtime(struct notifier_block *nfb,
unsigned long action, void *hcpu)
{
int cpu = (int)(long)hcpu;
switch (action) {
case CPU_DOWN_PREPARE:
case CPU_DOWN_PREPARE_FROZEN:
disable_runtime(cpu_rq(cpu));
return NOTIFY_OK;
case CPU_DOWN_FAILED:
case CPU_DOWN_FAILED_FROZEN:
case CPU_ONLINE:
case CPU_ONLINE_FROZEN:
enable_runtime(cpu_rq(cpu));
return NOTIFY_OK;
default:
return NOTIFY_DONE;
}
}
void __init sched_init_smp(void)
{
cpumask_var_t non_isolated_cpus;
alloc_cpumask_var(&non_isolated_cpus, GFP_KERNEL);
alloc_cpumask_var(&fallback_doms, GFP_KERNEL);
get_online_cpus();
mutex_lock(&sched_domains_mutex);
init_sched_domains(cpu_active_mask);
cpumask_andnot(non_isolated_cpus, cpu_possible_mask, cpu_isolated_map);
if (cpumask_empty(non_isolated_cpus))
cpumask_set_cpu(smp_processor_id(), non_isolated_cpus);
mutex_unlock(&sched_domains_mutex);
put_online_cpus();
hotcpu_notifier(cpuset_cpu_active, CPU_PRI_CPUSET_ACTIVE);
hotcpu_notifier(cpuset_cpu_inactive, CPU_PRI_CPUSET_INACTIVE);
/* RT runtime code needs to handle some hotplug events */
hotcpu_notifier(update_runtime, 0);
init_hrtick();
/* Move init over to a non-isolated CPU */
if (set_cpus_allowed_ptr(current, non_isolated_cpus) < 0)
BUG();
sched_init_granularity();
free_cpumask_var(non_isolated_cpus);
init_sched_rt_class();
}
#else
void __init sched_init_smp(void)
{
sched_init_granularity();
}
#endif /* CONFIG_SMP */
const_debug unsigned int sysctl_timer_migration = 1;
int in_sched_functions(unsigned long addr)
{
return in_lock_functions(addr) ||
(addr >= (unsigned long)__sched_text_start
&& addr < (unsigned long)__sched_text_end);
}
static void init_cfs_rq(struct cfs_rq *cfs_rq)
{
cfs_rq->tasks_timeline = RB_ROOT;
INIT_LIST_HEAD(&cfs_rq->tasks);
cfs_rq->min_vruntime = (u64)(-(1LL << 20));
#ifndef CONFIG_64BIT
cfs_rq->min_vruntime_copy = cfs_rq->min_vruntime;
#endif
}
static void init_rt_rq(struct rt_rq *rt_rq, struct rq *rq)
{
struct rt_prio_array *array;
int i;
array = &rt_rq->active;
for (i = 0; i < MAX_RT_PRIO; i++) {
INIT_LIST_HEAD(array->queue + i);
__clear_bit(i, array->bitmap);
}
/* delimiter for bitsearch: */
__set_bit(MAX_RT_PRIO, array->bitmap);
#if defined CONFIG_SMP
rt_rq->highest_prio.curr = MAX_RT_PRIO;
rt_rq->highest_prio.next = MAX_RT_PRIO;
rt_rq->rt_nr_migratory = 0;
rt_rq->overloaded = 0;
plist_head_init(&rt_rq->pushable_tasks);
#endif
rt_rq->rt_time = 0;
rt_rq->rt_throttled = 0;
rt_rq->rt_runtime = 0;
raw_spin_lock_init(&rt_rq->rt_runtime_lock);
}
#ifdef CONFIG_FAIR_GROUP_SCHED
static 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;
#ifdef CONFIG_SMP
/* allow initial update_cfs_load() to truncate */
cfs_rq->load_stamp = 1;
#endif
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;
else
se->cfs_rq = parent->my_q;
se->my_q = cfs_rq;
update_load_set(&se->load, 0);
se->parent = parent;
}
#endif
#ifdef CONFIG_RT_GROUP_SCHED
static void init_tg_rt_entry(struct task_group *tg, struct rt_rq *rt_rq,
struct sched_rt_entity *rt_se, int cpu,
struct sched_rt_entity *parent)
{
struct rq *rq = cpu_rq(cpu);
rt_rq->highest_prio.curr = MAX_RT_PRIO;
rt_rq->rt_nr_boosted = 0;
rt_rq->rq = rq;
rt_rq->tg = tg;
tg->rt_rq[cpu] = rt_rq;
tg->rt_se[cpu] = rt_se;
if (!rt_se)
return;
if (!parent)
rt_se->rt_rq = &rq->rt;
else
rt_se->rt_rq = parent->my_q;
rt_se->my_q = rt_rq;
rt_se->parent = parent;
INIT_LIST_HEAD(&rt_se->run_list);
}
#endif
void __init sched_init(void)
{
int i, j;
unsigned long alloc_size = 0, ptr;
#ifdef CONFIG_FAIR_GROUP_SCHED
alloc_size += 2 * nr_cpu_ids * sizeof(void **);
#endif
#ifdef CONFIG_RT_GROUP_SCHED
alloc_size += 2 * nr_cpu_ids * sizeof(void **);
#endif
#ifdef CONFIG_CPUMASK_OFFSTACK
alloc_size += num_possible_cpus() * cpumask_size();
#endif
if (alloc_size) {
ptr = (unsigned long)kzalloc(alloc_size, GFP_NOWAIT);
#ifdef CONFIG_FAIR_GROUP_SCHED
root_task_group.se = (struct sched_entity **)ptr;
ptr += nr_cpu_ids * sizeof(void **);
root_task_group.cfs_rq = (struct cfs_rq **)ptr;
ptr += nr_cpu_ids * sizeof(void **);
#endif /* CONFIG_FAIR_GROUP_SCHED */
#ifdef CONFIG_RT_GROUP_SCHED
root_task_group.rt_se = (struct sched_rt_entity **)ptr;
ptr += nr_cpu_ids * sizeof(void **);
root_task_group.rt_rq = (struct rt_rq **)ptr;
ptr += nr_cpu_ids * sizeof(void **);
#endif /* CONFIG_RT_GROUP_SCHED */
#ifdef CONFIG_CPUMASK_OFFSTACK
for_each_possible_cpu(i) {
per_cpu(load_balance_tmpmask, i) = (void *)ptr;
ptr += cpumask_size();
}
#endif /* CONFIG_CPUMASK_OFFSTACK */
}
#ifdef CONFIG_SMP
init_defrootdomain();
#endif
init_rt_bandwidth(&def_rt_bandwidth,
global_rt_period(), global_rt_runtime());
#ifdef CONFIG_RT_GROUP_SCHED
init_rt_bandwidth(&root_task_group.rt_bandwidth,
global_rt_period(), global_rt_runtime());
#endif /* CONFIG_RT_GROUP_SCHED */
#ifdef CONFIG_CGROUP_SCHED
list_add(&root_task_group.list, &task_groups);
INIT_LIST_HEAD(&root_task_group.children);
autogroup_init(&init_task);
#endif /* CONFIG_CGROUP_SCHED */
for_each_possible_cpu(i) {
struct rq *rq;
rq = cpu_rq(i);
raw_spin_lock_init(&rq->lock);
rq->nr_running = 0;
rq->calc_load_active = 0;
rq->calc_load_update = jiffies + LOAD_FREQ;
init_cfs_rq(&rq->cfs);
init_rt_rq(&rq->rt, rq);
#ifdef CONFIG_FAIR_GROUP_SCHED
root_task_group.shares = root_task_group_load;
INIT_LIST_HEAD(&rq->leaf_cfs_rq_list);
/*
* How much cpu bandwidth does root_task_group get?
*
* In case of task-groups formed thr' the cgroup filesystem, it
* gets 100% of the cpu resources in the system. This overall
* system cpu resource is divided among the tasks of
* root_task_group and its child task-groups in a fair manner,
* based on each entity's (task or task-group's) weight
* (se->load.weight).
*
* In other words, if root_task_group has 10 tasks of weight
* 1024) and two child groups A0 and A1 (of weight 1024 each),
* then A0's share of the cpu resource is:
*
* A0's bandwidth = 1024 / (10*1024 + 1024 + 1024) = 8.33%
*
* We achieve this by letting root_task_group's tasks sit
* directly in rq->cfs (i.e root_task_group->se[] = NULL).
*/
init_tg_cfs_entry(&root_task_group, &rq->cfs, NULL, i, NULL);
#endif /* CONFIG_FAIR_GROUP_SCHED */
rq->rt.rt_runtime = def_rt_bandwidth.rt_runtime;
#ifdef CONFIG_RT_GROUP_SCHED
INIT_LIST_HEAD(&rq->leaf_rt_rq_list);
init_tg_rt_entry(&root_task_group, &rq->rt, NULL, i, NULL);
#endif
for (j = 0; j < CPU_LOAD_IDX_MAX; j++)
rq->cpu_load[j] = 0;
rq->last_load_update_tick = jiffies;
#ifdef CONFIG_SMP
rq->sd = NULL;
rq->rd = NULL;
rq->cpu_power = SCHED_POWER_SCALE;
rq->post_schedule = 0;
rq->active_balance = 0;
rq->next_balance = jiffies;
rq->push_cpu = 0;
rq->cpu = i;
rq->online = 0;
rq->idle_stamp = 0;
rq->avg_idle = 2*sysctl_sched_migration_cost;
rq_attach_root(rq, &def_root_domain);
#ifdef CONFIG_NO_HZ
rq->nohz_balance_kick = 0;
init_sched_softirq_csd(&per_cpu(remote_sched_softirq_cb, i));
#endif
#endif
init_rq_hrtick(rq);
atomic_set(&rq->nr_iowait, 0);
}
set_load_weight(&init_task);
#ifdef CONFIG_PREEMPT_NOTIFIERS
INIT_HLIST_HEAD(&init_task.preempt_notifiers);
#endif
#ifdef CONFIG_SMP
open_softirq(SCHED_SOFTIRQ, run_rebalance_domains);
#endif
#ifdef CONFIG_RT_MUTEXES
plist_head_init(&init_task.pi_waiters);
#endif
/*
* The boot idle thread does lazy MMU switching as well:
*/
atomic_inc(&init_mm.mm_count);
enter_lazy_tlb(&init_mm, current);
/*
* Make us the idle thread. Technically, schedule() should not be
* called from this thread, however somewhere below it might be,
* but because we are the idle thread, we just pick up running again
* when this runqueue becomes "idle".
*/
init_idle(current, smp_processor_id());
calc_load_update = jiffies + LOAD_FREQ;
/*
* During early bootup we pretend to be a normal task:
*/
current->sched_class = &fair_sched_class;
/* Allocate the nohz_cpu_mask if CONFIG_CPUMASK_OFFSTACK */
zalloc_cpumask_var(&nohz_cpu_mask, GFP_NOWAIT);
#ifdef CONFIG_SMP
zalloc_cpumask_var(&sched_domains_tmpmask, GFP_NOWAIT);
#ifdef CONFIG_NO_HZ
zalloc_cpumask_var(&nohz.idle_cpus_mask, GFP_NOWAIT);
alloc_cpumask_var(&nohz.grp_idle_mask, GFP_NOWAIT);
atomic_set(&nohz.load_balancer, nr_cpu_ids);
atomic_set(&nohz.first_pick_cpu, nr_cpu_ids);
atomic_set(&nohz.second_pick_cpu, nr_cpu_ids);
#endif
/* May be allocated at isolcpus cmdline parse time */
if (cpu_isolated_map == NULL)
zalloc_cpumask_var(&cpu_isolated_map, GFP_NOWAIT);
#endif /* SMP */
scheduler_running = 1;
}
#ifdef CONFIG_DEBUG_ATOMIC_SLEEP
static inline int preempt_count_equals(int preempt_offset)
{
int nested = (preempt_count() & ~PREEMPT_ACTIVE) + rcu_preempt_depth();
return (nested == preempt_offset);
}
void __might_sleep(const char *file, int line, int preempt_offset)
{
static unsigned long prev_jiffy; /* ratelimiting */
if ((preempt_count_equals(preempt_offset) && !irqs_disabled()) ||
system_state != SYSTEM_RUNNING || oops_in_progress)
return;
if (time_before(jiffies, prev_jiffy + HZ) && prev_jiffy)
return;
prev_jiffy = jiffies;
printk(KERN_ERR
"BUG: sleeping function called from invalid context at %s:%d\n",
file, line);
printk(KERN_ERR
"in_atomic(): %d, irqs_disabled(): %d, pid: %d, name: %s\n",
in_atomic(), irqs_disabled(),
current->pid, current->comm);
debug_show_held_locks(current);
if (irqs_disabled())
print_irqtrace_events(current);
dump_stack();
}
EXPORT_SYMBOL(__might_sleep);
#endif
#ifdef CONFIG_MAGIC_SYSRQ
static void normalize_task(struct rq *rq, struct task_struct *p)
{
const struct sched_class *prev_class = p->sched_class;
int old_prio = p->prio;
int on_rq;
on_rq = p->on_rq;
if (on_rq)
deactivate_task(rq, p, 0);
__setscheduler(rq, p, SCHED_NORMAL, 0);
if (on_rq) {
activate_task(rq, p, 0);
resched_task(rq->curr);
}
check_class_changed(rq, p, prev_class, old_prio);
}
void normalize_rt_tasks(void)
{
struct task_struct *g, *p;
unsigned long flags;
struct rq *rq;
read_lock_irqsave(&tasklist_lock, flags);
do_each_thread(g, p) {
/*
* Only normalize user tasks:
*/
if (!p->mm)
continue;
p->se.exec_start = 0;
#ifdef CONFIG_SCHEDSTATS
p->se.statistics.wait_start = 0;
p->se.statistics.sleep_start = 0;
p->se.statistics.block_start = 0;
#endif
if (!rt_task(p)) {
/*
* Renice negative nice level userspace
* tasks back to 0:
*/
if (TASK_NICE(p) < 0 && p->mm)
set_user_nice(p, 0);
continue;
}
raw_spin_lock(&p->pi_lock);
rq = __task_rq_lock(p);
normalize_task(rq, p);
__task_rq_unlock(rq);
raw_spin_unlock(&p->pi_lock);
} while_each_thread(g, p);
read_unlock_irqrestore(&tasklist_lock, flags);
}
#endif /* CONFIG_MAGIC_SYSRQ */
#if defined(CONFIG_IA64) || defined(CONFIG_KGDB_KDB)
/*
* These functions are only useful for the IA64 MCA handling, or kdb.
*
* They can only be called when the whole system has been
* stopped - every CPU needs to be quiescent, and no scheduling
* activity can take place. Using them for anything else would
* be a serious bug, and as a result, they aren't even visible
* under any other configuration.
*/
/**
* curr_task - return the current task for a given cpu.
* @cpu: the processor in question.
*
* ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
*/
struct task_struct *curr_task(int cpu)
{
return cpu_curr(cpu);
}
#endif /* defined(CONFIG_IA64) || defined(CONFIG_KGDB_KDB) */
#ifdef CONFIG_IA64
/**
* set_curr_task - set the current task for a given cpu.
* @cpu: the processor in question.
* @p: the task pointer to set.
*
* Description: This function must only be used when non-maskable interrupts
* are serviced on a separate stack. It allows the architecture to switch the
* notion of the current task on a cpu in a non-blocking manner. This function
* must be called with all CPU's synchronized, and interrupts disabled, the
* and caller must save the original value of the current task (see
* curr_task() above) and restore that value before reenabling interrupts and
* re-starting the system.
*
* ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
*/
void set_curr_task(int cpu, struct task_struct *p)
{
cpu_curr(cpu) = p;
}
#endif
#ifdef CONFIG_FAIR_GROUP_SCHED
static void free_fair_sched_group(struct task_group *tg)
{
int i;
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);
}
static
int alloc_fair_sched_group(struct task_group *tg, struct task_group *parent)
{
struct cfs_rq *cfs_rq;
struct sched_entity *se;
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;
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]);
}
return 1;
err_free_rq:
kfree(cfs_rq);
err:
return 0;
}
static inline void unregister_fair_sched_group(struct task_group *tg, int cpu)
{
struct rq *rq = cpu_rq(cpu);
unsigned long flags;
/*
* 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)
return;
raw_spin_lock_irqsave(&rq->lock, flags);
list_del_leaf_cfs_rq(tg->cfs_rq[cpu]);
raw_spin_unlock_irqrestore(&rq->lock, flags);
}
#else /* !CONFIG_FAIR_GROUP_SCHED */
static inline void free_fair_sched_group(struct task_group *tg)
{
}
static inline
int alloc_fair_sched_group(struct task_group *tg, struct task_group *parent)
{
return 1;
}
static inline void unregister_fair_sched_group(struct task_group *tg, int cpu)
{
}
#endif /* CONFIG_FAIR_GROUP_SCHED */
#ifdef CONFIG_RT_GROUP_SCHED
static void free_rt_sched_group(struct task_group *tg)
{
int i;
if (tg->rt_se)
destroy_rt_bandwidth(&tg->rt_bandwidth);
for_each_possible_cpu(i) {
if (tg->rt_rq)
kfree(tg->rt_rq[i]);
if (tg->rt_se)
kfree(tg->rt_se[i]);
}
kfree(tg->rt_rq);
kfree(tg->rt_se);
}
static
int alloc_rt_sched_group(struct task_group *tg, struct task_group *parent)
{
struct rt_rq *rt_rq;
struct sched_rt_entity *rt_se;
int i;
tg->rt_rq = kzalloc(sizeof(rt_rq) * nr_cpu_ids, GFP_KERNEL);
if (!tg->rt_rq)
goto err;
tg->rt_se = kzalloc(sizeof(rt_se) * nr_cpu_ids, GFP_KERNEL);
if (!tg->rt_se)
goto err;
init_rt_bandwidth(&tg->rt_bandwidth,
ktime_to_ns(def_rt_bandwidth.rt_period), 0);
for_each_possible_cpu(i) {
rt_rq = kzalloc_node(sizeof(struct rt_rq),
GFP_KERNEL, cpu_to_node(i));
if (!rt_rq)
goto err;
rt_se = kzalloc_node(sizeof(struct sched_rt_entity),
GFP_KERNEL, cpu_to_node(i));
if (!rt_se)
goto err_free_rq;
init_rt_rq(rt_rq, cpu_rq(i));
rt_rq->rt_runtime = tg->rt_bandwidth.rt_runtime;
init_tg_rt_entry(tg, rt_rq, rt_se, i, parent->rt_se[i]);
}
return 1;
err_free_rq:
kfree(rt_rq);
err:
return 0;
}
#else /* !CONFIG_RT_GROUP_SCHED */
static inline void free_rt_sched_group(struct task_group *tg)
{
}
static inline
int alloc_rt_sched_group(struct task_group *tg, struct task_group *parent)
{
return 1;
}
#endif /* CONFIG_RT_GROUP_SCHED */
#ifdef CONFIG_CGROUP_SCHED
static void free_sched_group(struct task_group *tg)
{
free_fair_sched_group(tg);
free_rt_sched_group(tg);
autogroup_free(tg);
kfree(tg);
}
/* allocate runqueue etc for a new task group */
struct task_group *sched_create_group(struct task_group *parent)
{
struct task_group *tg;
unsigned long flags;
tg = kzalloc(sizeof(*tg), GFP_KERNEL);
if (!tg)
return ERR_PTR(-ENOMEM);
if (!alloc_fair_sched_group(tg, parent))
goto err;
if (!alloc_rt_sched_group(tg, parent))
goto err;
spin_lock_irqsave(&task_group_lock, flags);
list_add_rcu(&tg->list, &task_groups);
WARN_ON(!parent); /* root should already exist */
tg->parent = parent;
INIT_LIST_HEAD(&tg->children);
list_add_rcu(&tg->siblings, &parent->children);
spin_unlock_irqrestore(&task_group_lock, flags);
return tg;
err:
free_sched_group(tg);
return ERR_PTR(-ENOMEM);
}
/* rcu callback to free various structures associated with a task group */
static void free_sched_group_rcu(struct rcu_head *rhp)
{
/* now it should be safe to free those cfs_rqs */
free_sched_group(container_of(rhp, struct task_group, rcu));
}
/* Destroy runqueue etc associated with a task group */
void sched_destroy_group(struct task_group *tg)
{
unsigned long flags;
int i;
/* end participation in shares distribution */
for_each_possible_cpu(i)
unregister_fair_sched_group(tg, i);
spin_lock_irqsave(&task_group_lock, flags);
list_del_rcu(&tg->list);
list_del_rcu(&tg->siblings);
spin_unlock_irqrestore(&task_group_lock, flags);
/* wait for possible concurrent references to cfs_rqs complete */
call_rcu(&tg->rcu, free_sched_group_rcu);
}
/* change task's runqueue when it moves between groups.
* The caller of this function should have put the task in its new group
* by now. This function just updates tsk->se.cfs_rq and tsk->se.parent to
* reflect its new group.
*/
void sched_move_task(struct task_struct *tsk)
{
int on_rq, running;
unsigned long flags;
struct rq *rq;
rq = task_rq_lock(tsk, &flags);
running = task_current(rq, tsk);
on_rq = tsk->on_rq;
if (on_rq)
dequeue_task(rq, tsk, 0);
if (unlikely(running))
tsk->sched_class->put_prev_task(rq, tsk);
#ifdef CONFIG_FAIR_GROUP_SCHED
if (tsk->sched_class->task_move_group)
tsk->sched_class->task_move_group(tsk, on_rq);
else
#endif
set_task_rq(tsk, task_cpu(tsk));
if (unlikely(running))
tsk->sched_class->set_curr_task(rq);
if (on_rq)
enqueue_task(rq, tsk, 0);
task_rq_unlock(rq, tsk, &flags);
}
#endif /* CONFIG_CGROUP_SCHED */
#ifdef CONFIG_FAIR_GROUP_SCHED
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);
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;
}
unsigned long sched_group_shares(struct task_group *tg)
{
return tg->shares;
}
#endif
#ifdef CONFIG_RT_GROUP_SCHED
/*
* Ensure that the real time constraints are schedulable.
*/
static DEFINE_MUTEX(rt_constraints_mutex);
static unsigned long to_ratio(u64 period, u64 runtime)
{
if (runtime == RUNTIME_INF)
return 1ULL << 20;
return div64_u64(runtime << 20, period);
}
/* Must be called with tasklist_lock held */
static inline int tg_has_rt_tasks(struct task_group *tg)
{
struct task_struct *g, *p;
do_each_thread(g, p) {
if (rt_task(p) && rt_rq_of_se(&p->rt)->tg == tg)
return 1;
} while_each_thread(g, p);
return 0;
}
struct rt_schedulable_data {
struct task_group *tg;
u64 rt_period;
u64 rt_runtime;
};
static int tg_schedulable(struct task_group *tg, void *data)
{
struct rt_schedulable_data *d = data;
struct task_group *child;
unsigned long total, sum = 0;
u64 period, runtime;
period = ktime_to_ns(tg->rt_bandwidth.rt_period);
runtime = tg->rt_bandwidth.rt_runtime;
if (tg == d->tg) {
period = d->rt_period;
runtime = d->rt_runtime;
}
/*
* Cannot have more runtime than the period.
*/
if (runtime > period && runtime != RUNTIME_INF)
return -EINVAL;
/*
* Ensure we don't starve existing RT tasks.
*/
if (rt_bandwidth_enabled() && !runtime && tg_has_rt_tasks(tg))
return -EBUSY;
total = to_ratio(period, runtime);
/*
* Nobody can have more than the global setting allows.
*/
if (total > to_ratio(global_rt_period(), global_rt_runtime()))
return -EINVAL;
/*
* The sum of our children's runtime should not exceed our own.
*/
list_for_each_entry_rcu(child, &tg->children, siblings) {
period = ktime_to_ns(child->rt_bandwidth.rt_period);
runtime = child->rt_bandwidth.rt_runtime;
if (child == d->tg) {
period = d->rt_period;
runtime = d->rt_runtime;
}
sum += to_ratio(period, runtime);
}
if (sum > total)
return -EINVAL;
return 0;
}
static int __rt_schedulable(struct task_group *tg, u64 period, u64 runtime)
{
struct rt_schedulable_data data = {
.tg = tg,
.rt_period = period,
.rt_runtime = runtime,
};
return walk_tg_tree(tg_schedulable, tg_nop, &data);
}
static int tg_set_bandwidth(struct task_group *tg,
u64 rt_period, u64 rt_runtime)
{
int i, err = 0;
mutex_lock(&rt_constraints_mutex);
read_lock(&tasklist_lock);
err = __rt_schedulable(tg, rt_period, rt_runtime);
if (err)
goto unlock;
raw_spin_lock_irq(&tg->rt_bandwidth.rt_runtime_lock);
tg->rt_bandwidth.rt_period = ns_to_ktime(rt_period);
tg->rt_bandwidth.rt_runtime = rt_runtime;
for_each_possible_cpu(i) {
struct rt_rq *rt_rq = tg->rt_rq[i];
raw_spin_lock(&rt_rq->rt_runtime_lock);
rt_rq->rt_runtime = rt_runtime;
raw_spin_unlock(&rt_rq->rt_runtime_lock);
}
raw_spin_unlock_irq(&tg->rt_bandwidth.rt_runtime_lock);
unlock:
read_unlock(&tasklist_lock);
mutex_unlock(&rt_constraints_mutex);
return err;
}
int sched_group_set_rt_runtime(struct task_group *tg, long rt_runtime_us)
{
u64 rt_runtime, rt_period;
rt_period = ktime_to_ns(tg->rt_bandwidth.rt_period);
rt_runtime = (u64)rt_runtime_us * NSEC_PER_USEC;
if (rt_runtime_us < 0)
rt_runtime = RUNTIME_INF;
return tg_set_bandwidth(tg, rt_period, rt_runtime);
}
long sched_group_rt_runtime(struct task_group *tg)
{
u64 rt_runtime_us;
if (tg->rt_bandwidth.rt_runtime == RUNTIME_INF)
return -1;
rt_runtime_us = tg->rt_bandwidth.rt_runtime;
do_div(rt_runtime_us, NSEC_PER_USEC);
return rt_runtime_us;
}
int sched_group_set_rt_period(struct task_group *tg, long rt_period_us)
{
u64 rt_runtime, rt_period;
rt_period = (u64)rt_period_us * NSEC_PER_USEC;
rt_runtime = tg->rt_bandwidth.rt_runtime;
if (rt_period == 0)
return -EINVAL;
return tg_set_bandwidth(tg, rt_period, rt_runtime);
}
long sched_group_rt_period(struct task_group *tg)
{
u64 rt_period_us;
rt_period_us = ktime_to_ns(tg->rt_bandwidth.rt_period);
do_div(rt_period_us, NSEC_PER_USEC);
return rt_period_us;
}
static int sched_rt_global_constraints(void)
{
u64 runtime, period;
int ret = 0;
if (sysctl_sched_rt_period <= 0)
return -EINVAL;
runtime = global_rt_runtime();
period = global_rt_period();
/*
* Sanity check on the sysctl variables.
*/
if (runtime > period && runtime != RUNTIME_INF)
return -EINVAL;
mutex_lock(&rt_constraints_mutex);
read_lock(&tasklist_lock);
ret = __rt_schedulable(NULL, 0, 0);
read_unlock(&tasklist_lock);
mutex_unlock(&rt_constraints_mutex);
return ret;
}
int sched_rt_can_attach(struct task_group *tg, struct task_struct *tsk)
{
/* Don't accept realtime tasks when there is no way for them to run */
if (rt_task(tsk) && tg->rt_bandwidth.rt_runtime == 0)
return 0;
return 1;
}
#else /* !CONFIG_RT_GROUP_SCHED */
static int sched_rt_global_constraints(void)
{
unsigned long flags;
int i;
if (sysctl_sched_rt_period <= 0)
return -EINVAL;
/*
* There's always some RT tasks in the root group
* -- migration, kstopmachine etc..
*/
if (sysctl_sched_rt_runtime == 0)
return -EBUSY;
raw_spin_lock_irqsave(&def_rt_bandwidth.rt_runtime_lock, flags);
for_each_possible_cpu(i) {
struct rt_rq *rt_rq = &cpu_rq(i)->rt;
raw_spin_lock(&rt_rq->rt_runtime_lock);
rt_rq->rt_runtime = global_rt_runtime();
raw_spin_unlock(&rt_rq->rt_runtime_lock);
}
raw_spin_unlock_irqrestore(&def_rt_bandwidth.rt_runtime_lock, flags);
return 0;
}
#endif /* CONFIG_RT_GROUP_SCHED */
int sched_rt_handler(struct ctl_table *table, int write,
void __user *buffer, size_t *lenp,
loff_t *ppos)
{
int ret;
int old_period, old_runtime;
static DEFINE_MUTEX(mutex);
mutex_lock(&mutex);
old_period = sysctl_sched_rt_period;
old_runtime = sysctl_sched_rt_runtime;
ret = proc_dointvec(table, write, buffer, lenp, ppos);
if (!ret && write) {
ret = sched_rt_global_constraints();
if (ret) {
sysctl_sched_rt_period = old_period;
sysctl_sched_rt_runtime = old_runtime;
} else {
def_rt_bandwidth.rt_runtime = global_rt_runtime();
def_rt_bandwidth.rt_period =
ns_to_ktime(global_rt_period());
}
}
mutex_unlock(&mutex);
return ret;
}
#ifdef CONFIG_CGROUP_SCHED
/* return corresponding task_group object of a cgroup */
static inline struct task_group *cgroup_tg(struct cgroup *cgrp)
{
return container_of(cgroup_subsys_state(cgrp, cpu_cgroup_subsys_id),
struct task_group, css);
}
static struct cgroup_subsys_state *
cpu_cgroup_create(struct cgroup_subsys *ss, struct cgroup *cgrp)
{
struct task_group *tg, *parent;
if (!cgrp->parent) {
/* This is early initialization for the top cgroup */
return &root_task_group.css;
}
parent = cgroup_tg(cgrp->parent);
tg = sched_create_group(parent);
if (IS_ERR(tg))
return ERR_PTR(-ENOMEM);
return &tg->css;
}
static void
cpu_cgroup_destroy(struct cgroup_subsys *ss, struct cgroup *cgrp)
{
struct task_group *tg = cgroup_tg(cgrp);
sched_destroy_group(tg);
}
static int
cpu_cgroup_can_attach_task(struct cgroup *cgrp, struct task_struct *tsk)
{
#ifdef CONFIG_RT_GROUP_SCHED
if (!sched_rt_can_attach(cgroup_tg(cgrp), tsk))
return -EINVAL;
#else
/* We don't support RT-tasks being in separate groups */
if (tsk->sched_class != &fair_sched_class)
return -EINVAL;
#endif
return 0;
}
static void
cpu_cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk)
{
sched_move_task(tsk);
}
static void
cpu_cgroup_exit(struct cgroup_subsys *ss, struct cgroup *cgrp,
struct cgroup *old_cgrp, struct task_struct *task)
{
/*
* cgroup_exit() is called in the copy_process() failure path.
* Ignore this case since the task hasn't ran yet, this avoids
* trying to poke a half freed task state from generic code.
*/
if (!(task->flags & PF_EXITING))
return;
sched_move_task(task);
}
#ifdef CONFIG_FAIR_GROUP_SCHED
static int cpu_shares_write_u64(struct cgroup *cgrp, struct cftype *cftype,
u64 shareval)
{
return sched_group_set_shares(cgroup_tg(cgrp), scale_load(shareval));
}
static u64 cpu_shares_read_u64(struct cgroup *cgrp, struct cftype *cft)
{
struct task_group *tg = cgroup_tg(cgrp);
return (u64) scale_load_down(tg->shares);
}
#endif /* CONFIG_FAIR_GROUP_SCHED */
#ifdef CONFIG_RT_GROUP_SCHED
static int cpu_rt_runtime_write(struct cgroup *cgrp, struct cftype *cft,
s64 val)
{
return sched_group_set_rt_runtime(cgroup_tg(cgrp), val);
}
static s64 cpu_rt_runtime_read(struct cgroup *cgrp, struct cftype *cft)
{
return sched_group_rt_runtime(cgroup_tg(cgrp));
}
static int cpu_rt_period_write_uint(struct cgroup *cgrp, struct cftype *cftype,
u64 rt_period_us)
{
return sched_group_set_rt_period(cgroup_tg(cgrp), rt_period_us);
}
static u64 cpu_rt_period_read_uint(struct cgroup *cgrp, struct cftype *cft)
{
return sched_group_rt_period(cgroup_tg(cgrp));
}
#endif /* CONFIG_RT_GROUP_SCHED */
static struct cftype cpu_files[] = {
#ifdef CONFIG_FAIR_GROUP_SCHED
{
.name = "shares",
.read_u64 = cpu_shares_read_u64,
.write_u64 = cpu_shares_write_u64,
},
#endif
#ifdef CONFIG_RT_GROUP_SCHED
{
.name = "rt_runtime_us",
.read_s64 = cpu_rt_runtime_read,
.write_s64 = cpu_rt_runtime_write,
},
{
.name = "rt_period_us",
.read_u64 = cpu_rt_period_read_uint,
.write_u64 = cpu_rt_period_write_uint,
},
#endif
};
static int cpu_cgroup_populate(struct cgroup_subsys *ss, struct cgroup *cont)
{
return cgroup_add_files(cont, ss, cpu_files, ARRAY_SIZE(cpu_files));
}
struct cgroup_subsys cpu_cgroup_subsys = {
.name = "cpu",
.create = cpu_cgroup_create,
.destroy = cpu_cgroup_destroy,
.can_attach_task = cpu_cgroup_can_attach_task,
.attach_task = cpu_cgroup_attach_task,
.exit = cpu_cgroup_exit,
.populate = cpu_cgroup_populate,
.subsys_id = cpu_cgroup_subsys_id,
.early_init = 1,
};
#endif /* CONFIG_CGROUP_SCHED */
#ifdef CONFIG_CGROUP_CPUACCT
/*
* CPU accounting code for task groups.
*
* Based on the work by Paul Menage (menage@google.com) and Balbir Singh
* (balbir@in.ibm.com).
*/
/* track cpu usage of a group of tasks and its child groups */
struct cpuacct {
struct cgroup_subsys_state css;
/* cpuusage holds pointer to a u64-type object on every cpu */
u64 __percpu *cpuusage;
struct percpu_counter cpustat[CPUACCT_STAT_NSTATS];
struct cpuacct *parent;
};
struct cgroup_subsys cpuacct_subsys;
/* return cpu accounting group corresponding to this container */
static inline struct cpuacct *cgroup_ca(struct cgroup *cgrp)
{
return container_of(cgroup_subsys_state(cgrp, cpuacct_subsys_id),
struct cpuacct, css);
}
/* return cpu accounting group to which this task belongs */
static inline struct cpuacct *task_ca(struct task_struct *tsk)
{
return container_of(task_subsys_state(tsk, cpuacct_subsys_id),
struct cpuacct, css);
}
/* create a new cpu accounting group */
static struct cgroup_subsys_state *cpuacct_create(
struct cgroup_subsys *ss, struct cgroup *cgrp)
{
struct cpuacct *ca = kzalloc(sizeof(*ca), GFP_KERNEL);
int i;
if (!ca)
goto out;
ca->cpuusage = alloc_percpu(u64);
if (!ca->cpuusage)
goto out_free_ca;
for (i = 0; i < CPUACCT_STAT_NSTATS; i++)
if (percpu_counter_init(&ca->cpustat[i], 0))
goto out_free_counters;
if (cgrp->parent)
ca->parent = cgroup_ca(cgrp->parent);
return &ca->css;
out_free_counters:
while (--i >= 0)
percpu_counter_destroy(&ca->cpustat[i]);
free_percpu(ca->cpuusage);
out_free_ca:
kfree(ca);
out:
return ERR_PTR(-ENOMEM);
}
/* destroy an existing cpu accounting group */
static void
cpuacct_destroy(struct cgroup_subsys *ss, struct cgroup *cgrp)
{
struct cpuacct *ca = cgroup_ca(cgrp);
int i;
for (i = 0; i < CPUACCT_STAT_NSTATS; i++)
percpu_counter_destroy(&ca->cpustat[i]);
free_percpu(ca->cpuusage);
kfree(ca);
}
static u64 cpuacct_cpuusage_read(struct cpuacct *ca, int cpu)
{
u64 *cpuusage = per_cpu_ptr(ca->cpuusage, cpu);
u64 data;
#ifndef CONFIG_64BIT
/*
* Take rq->lock to make 64-bit read safe on 32-bit platforms.
*/
raw_spin_lock_irq(&cpu_rq(cpu)->lock);
data = *cpuusage;
raw_spin_unlock_irq(&cpu_rq(cpu)->lock);
#else
data = *cpuusage;
#endif
return data;
}
static void cpuacct_cpuusage_write(struct cpuacct *ca, int cpu, u64 val)
{
u64 *cpuusage = per_cpu_ptr(ca->cpuusage, cpu);
#ifndef CONFIG_64BIT
/*
* Take rq->lock to make 64-bit write safe on 32-bit platforms.
*/
raw_spin_lock_irq(&cpu_rq(cpu)->lock);
*cpuusage = val;
raw_spin_unlock_irq(&cpu_rq(cpu)->lock);
#else
*cpuusage = val;
#endif
}
/* return total cpu usage (in nanoseconds) of a group */
static u64 cpuusage_read(struct cgroup *cgrp, struct cftype *cft)
{
struct cpuacct *ca = cgroup_ca(cgrp);
u64 totalcpuusage = 0;
int i;
for_each_present_cpu(i)
totalcpuusage += cpuacct_cpuusage_read(ca, i);
return totalcpuusage;
}
static int cpuusage_write(struct cgroup *cgrp, struct cftype *cftype,
u64 reset)
{
struct cpuacct *ca = cgroup_ca(cgrp);
int err = 0;
int i;
if (reset) {
err = -EINVAL;
goto out;
}
for_each_present_cpu(i)
cpuacct_cpuusage_write(ca, i, 0);
out:
return err;
}
static int cpuacct_percpu_seq_read(struct cgroup *cgroup, struct cftype *cft,
struct seq_file *m)
{
struct cpuacct *ca = cgroup_ca(cgroup);
u64 percpu;
int i;
for_each_present_cpu(i) {
percpu = cpuacct_cpuusage_read(ca, i);
seq_printf(m, "%llu ", (unsigned long long) percpu);
}
seq_printf(m, "\n");
return 0;
}
static const char *cpuacct_stat_desc[] = {
[CPUACCT_STAT_USER] = "user",
[CPUACCT_STAT_SYSTEM] = "system",
};
static int cpuacct_stats_show(struct cgroup *cgrp, struct cftype *cft,
struct cgroup_map_cb *cb)
{
struct cpuacct *ca = cgroup_ca(cgrp);
int i;
for (i = 0; i < CPUACCT_STAT_NSTATS; i++) {
s64 val = percpu_counter_read(&ca->cpustat[i]);
val = cputime64_to_clock_t(val);
cb->fill(cb, cpuacct_stat_desc[i], val);
}
return 0;
}
static struct cftype files[] = {
{
.name = "usage",
.read_u64 = cpuusage_read,
.write_u64 = cpuusage_write,
},
{
.name = "usage_percpu",
.read_seq_string = cpuacct_percpu_seq_read,
},
{
.name = "stat",
.read_map = cpuacct_stats_show,
},
};
static int cpuacct_populate(struct cgroup_subsys *ss, struct cgroup *cgrp)
{
return cgroup_add_files(cgrp, ss, files, ARRAY_SIZE(files));
}
/*
* charge this task's execution time to its accounting group.
*
* called with rq->lock held.
*/
static void cpuacct_charge(struct task_struct *tsk, u64 cputime)
{
struct cpuacct *ca;
int cpu;
if (unlikely(!cpuacct_subsys.active))
return;
cpu = task_cpu(tsk);
rcu_read_lock();
ca = task_ca(tsk);
for (; ca; ca = ca->parent) {
u64 *cpuusage = per_cpu_ptr(ca->cpuusage, cpu);
*cpuusage += cputime;
}
rcu_read_unlock();
}
/*
* When CONFIG_VIRT_CPU_ACCOUNTING is enabled one jiffy can be very large
* in cputime_t units. As a result, cpuacct_update_stats calls
* percpu_counter_add with values large enough to always overflow the
* per cpu batch limit causing bad SMP scalability.
*
* To fix this we scale percpu_counter_batch by cputime_one_jiffy so we
* batch the same amount of time with CONFIG_VIRT_CPU_ACCOUNTING disabled
* and enabled. We cap it at INT_MAX which is the largest allowed batch value.
*/
#ifdef CONFIG_SMP
#define CPUACCT_BATCH \
min_t(long, percpu_counter_batch * cputime_one_jiffy, INT_MAX)
#else
#define CPUACCT_BATCH 0
#endif
/*
* Charge the system/user time to the task's accounting group.
*/
static void cpuacct_update_stats(struct task_struct *tsk,
enum cpuacct_stat_index idx, cputime_t val)
{
struct cpuacct *ca;
int batch = CPUACCT_BATCH;
if (unlikely(!cpuacct_subsys.active))
return;
rcu_read_lock();
ca = task_ca(tsk);
do {
__percpu_counter_add(&ca->cpustat[idx], val, batch);
ca = ca->parent;
} while (ca);
rcu_read_unlock();
}
struct cgroup_subsys cpuacct_subsys = {
.name = "cpuacct",
.create = cpuacct_create,
.destroy = cpuacct_destroy,
.populate = cpuacct_populate,
.subsys_id = cpuacct_subsys_id,
};
#endif /* CONFIG_CGROUP_CPUACCT */