| /* |
| * Interface for controlling IO bandwidth on a request queue |
| * |
| * Copyright (C) 2010 Vivek Goyal <vgoyal@redhat.com> |
| */ |
| |
| #include <linux/module.h> |
| #include <linux/slab.h> |
| #include <linux/blkdev.h> |
| #include <linux/bio.h> |
| #include <linux/blktrace_api.h> |
| #include "blk-cgroup.h" |
| #include "blk.h" |
| |
| /* Max dispatch from a group in 1 round */ |
| static int throtl_grp_quantum = 8; |
| |
| /* Total max dispatch from all groups in one round */ |
| static int throtl_quantum = 32; |
| |
| /* Throttling is performed over 100ms slice and after that slice is renewed */ |
| static unsigned long throtl_slice = HZ/10; /* 100 ms */ |
| |
| static struct blkcg_policy blkcg_policy_throtl; |
| |
| /* A workqueue to queue throttle related work */ |
| static struct workqueue_struct *kthrotld_workqueue; |
| |
| /* |
| * To implement hierarchical throttling, throtl_grps form a tree and bios |
| * are dispatched upwards level by level until they reach the top and get |
| * issued. When dispatching bios from the children and local group at each |
| * level, if the bios are dispatched into a single bio_list, there's a risk |
| * of a local or child group which can queue many bios at once filling up |
| * the list starving others. |
| * |
| * To avoid such starvation, dispatched bios are queued separately |
| * according to where they came from. When they are again dispatched to |
| * the parent, they're popped in round-robin order so that no single source |
| * hogs the dispatch window. |
| * |
| * throtl_qnode is used to keep the queued bios separated by their sources. |
| * Bios are queued to throtl_qnode which in turn is queued to |
| * throtl_service_queue and then dispatched in round-robin order. |
| * |
| * It's also used to track the reference counts on blkg's. A qnode always |
| * belongs to a throtl_grp and gets queued on itself or the parent, so |
| * incrementing the reference of the associated throtl_grp when a qnode is |
| * queued and decrementing when dequeued is enough to keep the whole blkg |
| * tree pinned while bios are in flight. |
| */ |
| struct throtl_qnode { |
| struct list_head node; /* service_queue->queued[] */ |
| struct bio_list bios; /* queued bios */ |
| struct throtl_grp *tg; /* tg this qnode belongs to */ |
| }; |
| |
| struct throtl_service_queue { |
| struct throtl_service_queue *parent_sq; /* the parent service_queue */ |
| |
| /* |
| * Bios queued directly to this service_queue or dispatched from |
| * children throtl_grp's. |
| */ |
| struct list_head queued[2]; /* throtl_qnode [READ/WRITE] */ |
| unsigned int nr_queued[2]; /* number of queued bios */ |
| |
| /* |
| * RB tree of active children throtl_grp's, which are sorted by |
| * their ->disptime. |
| */ |
| struct rb_root pending_tree; /* RB tree of active tgs */ |
| struct rb_node *first_pending; /* first node in the tree */ |
| unsigned int nr_pending; /* # queued in the tree */ |
| unsigned long first_pending_disptime; /* disptime of the first tg */ |
| struct timer_list pending_timer; /* fires on first_pending_disptime */ |
| }; |
| |
| enum tg_state_flags { |
| THROTL_TG_PENDING = 1 << 0, /* on parent's pending tree */ |
| THROTL_TG_WAS_EMPTY = 1 << 1, /* bio_lists[] became non-empty */ |
| }; |
| |
| #define rb_entry_tg(node) rb_entry((node), struct throtl_grp, rb_node) |
| |
| /* Per-cpu group stats */ |
| struct tg_stats_cpu { |
| /* total bytes transferred */ |
| struct blkg_rwstat service_bytes; |
| /* total IOs serviced, post merge */ |
| struct blkg_rwstat serviced; |
| }; |
| |
| struct throtl_grp { |
| /* must be the first member */ |
| struct blkg_policy_data pd; |
| |
| /* active throtl group service_queue member */ |
| struct rb_node rb_node; |
| |
| /* throtl_data this group belongs to */ |
| struct throtl_data *td; |
| |
| /* this group's service queue */ |
| struct throtl_service_queue service_queue; |
| |
| /* |
| * qnode_on_self is used when bios are directly queued to this |
| * throtl_grp so that local bios compete fairly with bios |
| * dispatched from children. qnode_on_parent is used when bios are |
| * dispatched from this throtl_grp into its parent and will compete |
| * with the sibling qnode_on_parents and the parent's |
| * qnode_on_self. |
| */ |
| struct throtl_qnode qnode_on_self[2]; |
| struct throtl_qnode qnode_on_parent[2]; |
| |
| /* |
| * Dispatch time in jiffies. This is the estimated time when group |
| * will unthrottle and is ready to dispatch more bio. It is used as |
| * key to sort active groups in service tree. |
| */ |
| unsigned long disptime; |
| |
| unsigned int flags; |
| |
| /* bytes per second rate limits */ |
| uint64_t bps[2]; |
| |
| /* IOPS limits */ |
| unsigned int iops[2]; |
| |
| /* Number of bytes disptached in current slice */ |
| uint64_t bytes_disp[2]; |
| /* Number of bio's dispatched in current slice */ |
| unsigned int io_disp[2]; |
| |
| /* When did we start a new slice */ |
| unsigned long slice_start[2]; |
| unsigned long slice_end[2]; |
| |
| /* Per cpu stats pointer */ |
| struct tg_stats_cpu __percpu *stats_cpu; |
| |
| /* List of tgs waiting for per cpu stats memory to be allocated */ |
| struct list_head stats_alloc_node; |
| }; |
| |
| struct throtl_data |
| { |
| /* service tree for active throtl groups */ |
| struct throtl_service_queue service_queue; |
| |
| struct request_queue *queue; |
| |
| /* Total Number of queued bios on READ and WRITE lists */ |
| unsigned int nr_queued[2]; |
| |
| /* |
| * number of total undestroyed groups |
| */ |
| unsigned int nr_undestroyed_grps; |
| |
| /* Work for dispatching throttled bios */ |
| struct work_struct dispatch_work; |
| }; |
| |
| /* list and work item to allocate percpu group stats */ |
| static DEFINE_SPINLOCK(tg_stats_alloc_lock); |
| static LIST_HEAD(tg_stats_alloc_list); |
| |
| static void tg_stats_alloc_fn(struct work_struct *); |
| static DECLARE_DELAYED_WORK(tg_stats_alloc_work, tg_stats_alloc_fn); |
| |
| static void throtl_pending_timer_fn(unsigned long arg); |
| |
| static inline struct throtl_grp *pd_to_tg(struct blkg_policy_data *pd) |
| { |
| return pd ? container_of(pd, struct throtl_grp, pd) : NULL; |
| } |
| |
| static inline struct throtl_grp *blkg_to_tg(struct blkcg_gq *blkg) |
| { |
| return pd_to_tg(blkg_to_pd(blkg, &blkcg_policy_throtl)); |
| } |
| |
| static inline struct blkcg_gq *tg_to_blkg(struct throtl_grp *tg) |
| { |
| return pd_to_blkg(&tg->pd); |
| } |
| |
| static inline struct throtl_grp *td_root_tg(struct throtl_data *td) |
| { |
| return blkg_to_tg(td->queue->root_blkg); |
| } |
| |
| /** |
| * sq_to_tg - return the throl_grp the specified service queue belongs to |
| * @sq: the throtl_service_queue of interest |
| * |
| * Return the throtl_grp @sq belongs to. If @sq is the top-level one |
| * embedded in throtl_data, %NULL is returned. |
| */ |
| static struct throtl_grp *sq_to_tg(struct throtl_service_queue *sq) |
| { |
| if (sq && sq->parent_sq) |
| return container_of(sq, struct throtl_grp, service_queue); |
| else |
| return NULL; |
| } |
| |
| /** |
| * sq_to_td - return throtl_data the specified service queue belongs to |
| * @sq: the throtl_service_queue of interest |
| * |
| * A service_queue can be embeded in either a throtl_grp or throtl_data. |
| * Determine the associated throtl_data accordingly and return it. |
| */ |
| static struct throtl_data *sq_to_td(struct throtl_service_queue *sq) |
| { |
| struct throtl_grp *tg = sq_to_tg(sq); |
| |
| if (tg) |
| return tg->td; |
| else |
| return container_of(sq, struct throtl_data, service_queue); |
| } |
| |
| /** |
| * throtl_log - log debug message via blktrace |
| * @sq: the service_queue being reported |
| * @fmt: printf format string |
| * @args: printf args |
| * |
| * The messages are prefixed with "throtl BLKG_NAME" if @sq belongs to a |
| * throtl_grp; otherwise, just "throtl". |
| * |
| * TODO: this should be made a function and name formatting should happen |
| * after testing whether blktrace is enabled. |
| */ |
| #define throtl_log(sq, fmt, args...) do { \ |
| struct throtl_grp *__tg = sq_to_tg((sq)); \ |
| struct throtl_data *__td = sq_to_td((sq)); \ |
| \ |
| (void)__td; \ |
| if ((__tg)) { \ |
| char __pbuf[128]; \ |
| \ |
| blkg_path(tg_to_blkg(__tg), __pbuf, sizeof(__pbuf)); \ |
| blk_add_trace_msg(__td->queue, "throtl %s " fmt, __pbuf, ##args); \ |
| } else { \ |
| blk_add_trace_msg(__td->queue, "throtl " fmt, ##args); \ |
| } \ |
| } while (0) |
| |
| /* |
| * Worker for allocating per cpu stat for tgs. This is scheduled on the |
| * system_wq once there are some groups on the alloc_list waiting for |
| * allocation. |
| */ |
| static void tg_stats_alloc_fn(struct work_struct *work) |
| { |
| static struct tg_stats_cpu *stats_cpu; /* this fn is non-reentrant */ |
| struct delayed_work *dwork = to_delayed_work(work); |
| bool empty = false; |
| |
| alloc_stats: |
| if (!stats_cpu) { |
| stats_cpu = alloc_percpu(struct tg_stats_cpu); |
| if (!stats_cpu) { |
| /* allocation failed, try again after some time */ |
| schedule_delayed_work(dwork, msecs_to_jiffies(10)); |
| return; |
| } |
| } |
| |
| spin_lock_irq(&tg_stats_alloc_lock); |
| |
| if (!list_empty(&tg_stats_alloc_list)) { |
| struct throtl_grp *tg = list_first_entry(&tg_stats_alloc_list, |
| struct throtl_grp, |
| stats_alloc_node); |
| swap(tg->stats_cpu, stats_cpu); |
| list_del_init(&tg->stats_alloc_node); |
| } |
| |
| empty = list_empty(&tg_stats_alloc_list); |
| spin_unlock_irq(&tg_stats_alloc_lock); |
| if (!empty) |
| goto alloc_stats; |
| } |
| |
| static void throtl_qnode_init(struct throtl_qnode *qn, struct throtl_grp *tg) |
| { |
| INIT_LIST_HEAD(&qn->node); |
| bio_list_init(&qn->bios); |
| qn->tg = tg; |
| } |
| |
| /** |
| * throtl_qnode_add_bio - add a bio to a throtl_qnode and activate it |
| * @bio: bio being added |
| * @qn: qnode to add bio to |
| * @queued: the service_queue->queued[] list @qn belongs to |
| * |
| * Add @bio to @qn and put @qn on @queued if it's not already on. |
| * @qn->tg's reference count is bumped when @qn is activated. See the |
| * comment on top of throtl_qnode definition for details. |
| */ |
| static void throtl_qnode_add_bio(struct bio *bio, struct throtl_qnode *qn, |
| struct list_head *queued) |
| { |
| bio_list_add(&qn->bios, bio); |
| if (list_empty(&qn->node)) { |
| list_add_tail(&qn->node, queued); |
| blkg_get(tg_to_blkg(qn->tg)); |
| } |
| } |
| |
| /** |
| * throtl_peek_queued - peek the first bio on a qnode list |
| * @queued: the qnode list to peek |
| */ |
| static struct bio *throtl_peek_queued(struct list_head *queued) |
| { |
| struct throtl_qnode *qn = list_first_entry(queued, struct throtl_qnode, node); |
| struct bio *bio; |
| |
| if (list_empty(queued)) |
| return NULL; |
| |
| bio = bio_list_peek(&qn->bios); |
| WARN_ON_ONCE(!bio); |
| return bio; |
| } |
| |
| /** |
| * throtl_pop_queued - pop the first bio form a qnode list |
| * @queued: the qnode list to pop a bio from |
| * @tg_to_put: optional out argument for throtl_grp to put |
| * |
| * Pop the first bio from the qnode list @queued. After popping, the first |
| * qnode is removed from @queued if empty or moved to the end of @queued so |
| * that the popping order is round-robin. |
| * |
| * When the first qnode is removed, its associated throtl_grp should be put |
| * too. If @tg_to_put is NULL, this function automatically puts it; |
| * otherwise, *@tg_to_put is set to the throtl_grp to put and the caller is |
| * responsible for putting it. |
| */ |
| static struct bio *throtl_pop_queued(struct list_head *queued, |
| struct throtl_grp **tg_to_put) |
| { |
| struct throtl_qnode *qn = list_first_entry(queued, struct throtl_qnode, node); |
| struct bio *bio; |
| |
| if (list_empty(queued)) |
| return NULL; |
| |
| bio = bio_list_pop(&qn->bios); |
| WARN_ON_ONCE(!bio); |
| |
| if (bio_list_empty(&qn->bios)) { |
| list_del_init(&qn->node); |
| if (tg_to_put) |
| *tg_to_put = qn->tg; |
| else |
| blkg_put(tg_to_blkg(qn->tg)); |
| } else { |
| list_move_tail(&qn->node, queued); |
| } |
| |
| return bio; |
| } |
| |
| /* init a service_queue, assumes the caller zeroed it */ |
| static void throtl_service_queue_init(struct throtl_service_queue *sq, |
| struct throtl_service_queue *parent_sq) |
| { |
| INIT_LIST_HEAD(&sq->queued[0]); |
| INIT_LIST_HEAD(&sq->queued[1]); |
| sq->pending_tree = RB_ROOT; |
| sq->parent_sq = parent_sq; |
| setup_timer(&sq->pending_timer, throtl_pending_timer_fn, |
| (unsigned long)sq); |
| } |
| |
| static void throtl_service_queue_exit(struct throtl_service_queue *sq) |
| { |
| del_timer_sync(&sq->pending_timer); |
| } |
| |
| static void throtl_pd_init(struct blkcg_gq *blkg) |
| { |
| struct throtl_grp *tg = blkg_to_tg(blkg); |
| struct throtl_data *td = blkg->q->td; |
| unsigned long flags; |
| int rw; |
| |
| throtl_service_queue_init(&tg->service_queue, &td->service_queue); |
| for (rw = READ; rw <= WRITE; rw++) { |
| throtl_qnode_init(&tg->qnode_on_self[rw], tg); |
| throtl_qnode_init(&tg->qnode_on_parent[rw], tg); |
| } |
| |
| RB_CLEAR_NODE(&tg->rb_node); |
| tg->td = td; |
| |
| tg->bps[READ] = -1; |
| tg->bps[WRITE] = -1; |
| tg->iops[READ] = -1; |
| tg->iops[WRITE] = -1; |
| |
| /* |
| * Ugh... We need to perform per-cpu allocation for tg->stats_cpu |
| * but percpu allocator can't be called from IO path. Queue tg on |
| * tg_stats_alloc_list and allocate from work item. |
| */ |
| spin_lock_irqsave(&tg_stats_alloc_lock, flags); |
| list_add(&tg->stats_alloc_node, &tg_stats_alloc_list); |
| schedule_delayed_work(&tg_stats_alloc_work, 0); |
| spin_unlock_irqrestore(&tg_stats_alloc_lock, flags); |
| } |
| |
| static void throtl_pd_exit(struct blkcg_gq *blkg) |
| { |
| struct throtl_grp *tg = blkg_to_tg(blkg); |
| unsigned long flags; |
| |
| spin_lock_irqsave(&tg_stats_alloc_lock, flags); |
| list_del_init(&tg->stats_alloc_node); |
| spin_unlock_irqrestore(&tg_stats_alloc_lock, flags); |
| |
| free_percpu(tg->stats_cpu); |
| |
| throtl_service_queue_exit(&tg->service_queue); |
| } |
| |
| static void throtl_pd_reset_stats(struct blkcg_gq *blkg) |
| { |
| struct throtl_grp *tg = blkg_to_tg(blkg); |
| int cpu; |
| |
| if (tg->stats_cpu == NULL) |
| return; |
| |
| for_each_possible_cpu(cpu) { |
| struct tg_stats_cpu *sc = per_cpu_ptr(tg->stats_cpu, cpu); |
| |
| blkg_rwstat_reset(&sc->service_bytes); |
| blkg_rwstat_reset(&sc->serviced); |
| } |
| } |
| |
| static struct throtl_grp *throtl_lookup_tg(struct throtl_data *td, |
| struct blkcg *blkcg) |
| { |
| /* |
| * This is the common case when there are no blkcgs. Avoid lookup |
| * in this case |
| */ |
| if (blkcg == &blkcg_root) |
| return td_root_tg(td); |
| |
| return blkg_to_tg(blkg_lookup(blkcg, td->queue)); |
| } |
| |
| static struct throtl_grp *throtl_lookup_create_tg(struct throtl_data *td, |
| struct blkcg *blkcg) |
| { |
| struct request_queue *q = td->queue; |
| struct throtl_grp *tg = NULL; |
| |
| /* |
| * This is the common case when there are no blkcgs. Avoid lookup |
| * in this case |
| */ |
| if (blkcg == &blkcg_root) { |
| tg = td_root_tg(td); |
| } else { |
| struct blkcg_gq *blkg; |
| |
| blkg = blkg_lookup_create(blkcg, q); |
| |
| /* if %NULL and @q is alive, fall back to root_tg */ |
| if (!IS_ERR(blkg)) |
| tg = blkg_to_tg(blkg); |
| else if (!blk_queue_dying(q)) |
| tg = td_root_tg(td); |
| } |
| |
| return tg; |
| } |
| |
| static struct throtl_grp * |
| throtl_rb_first(struct throtl_service_queue *parent_sq) |
| { |
| /* Service tree is empty */ |
| if (!parent_sq->nr_pending) |
| return NULL; |
| |
| if (!parent_sq->first_pending) |
| parent_sq->first_pending = rb_first(&parent_sq->pending_tree); |
| |
| if (parent_sq->first_pending) |
| return rb_entry_tg(parent_sq->first_pending); |
| |
| return NULL; |
| } |
| |
| static void rb_erase_init(struct rb_node *n, struct rb_root *root) |
| { |
| rb_erase(n, root); |
| RB_CLEAR_NODE(n); |
| } |
| |
| static void throtl_rb_erase(struct rb_node *n, |
| struct throtl_service_queue *parent_sq) |
| { |
| if (parent_sq->first_pending == n) |
| parent_sq->first_pending = NULL; |
| rb_erase_init(n, &parent_sq->pending_tree); |
| --parent_sq->nr_pending; |
| } |
| |
| static void update_min_dispatch_time(struct throtl_service_queue *parent_sq) |
| { |
| struct throtl_grp *tg; |
| |
| tg = throtl_rb_first(parent_sq); |
| if (!tg) |
| return; |
| |
| parent_sq->first_pending_disptime = tg->disptime; |
| } |
| |
| static void tg_service_queue_add(struct throtl_grp *tg) |
| { |
| struct throtl_service_queue *parent_sq = tg->service_queue.parent_sq; |
| struct rb_node **node = &parent_sq->pending_tree.rb_node; |
| struct rb_node *parent = NULL; |
| struct throtl_grp *__tg; |
| unsigned long key = tg->disptime; |
| int left = 1; |
| |
| while (*node != NULL) { |
| parent = *node; |
| __tg = rb_entry_tg(parent); |
| |
| if (time_before(key, __tg->disptime)) |
| node = &parent->rb_left; |
| else { |
| node = &parent->rb_right; |
| left = 0; |
| } |
| } |
| |
| if (left) |
| parent_sq->first_pending = &tg->rb_node; |
| |
| rb_link_node(&tg->rb_node, parent, node); |
| rb_insert_color(&tg->rb_node, &parent_sq->pending_tree); |
| } |
| |
| static void __throtl_enqueue_tg(struct throtl_grp *tg) |
| { |
| tg_service_queue_add(tg); |
| tg->flags |= THROTL_TG_PENDING; |
| tg->service_queue.parent_sq->nr_pending++; |
| } |
| |
| static void throtl_enqueue_tg(struct throtl_grp *tg) |
| { |
| if (!(tg->flags & THROTL_TG_PENDING)) |
| __throtl_enqueue_tg(tg); |
| } |
| |
| static void __throtl_dequeue_tg(struct throtl_grp *tg) |
| { |
| throtl_rb_erase(&tg->rb_node, tg->service_queue.parent_sq); |
| tg->flags &= ~THROTL_TG_PENDING; |
| } |
| |
| static void throtl_dequeue_tg(struct throtl_grp *tg) |
| { |
| if (tg->flags & THROTL_TG_PENDING) |
| __throtl_dequeue_tg(tg); |
| } |
| |
| /* Call with queue lock held */ |
| static void throtl_schedule_pending_timer(struct throtl_service_queue *sq, |
| unsigned long expires) |
| { |
| mod_timer(&sq->pending_timer, expires); |
| throtl_log(sq, "schedule timer. delay=%lu jiffies=%lu", |
| expires - jiffies, jiffies); |
| } |
| |
| /** |
| * throtl_schedule_next_dispatch - schedule the next dispatch cycle |
| * @sq: the service_queue to schedule dispatch for |
| * @force: force scheduling |
| * |
| * Arm @sq->pending_timer so that the next dispatch cycle starts on the |
| * dispatch time of the first pending child. Returns %true if either timer |
| * is armed or there's no pending child left. %false if the current |
| * dispatch window is still open and the caller should continue |
| * dispatching. |
| * |
| * If @force is %true, the dispatch timer is always scheduled and this |
| * function is guaranteed to return %true. This is to be used when the |
| * caller can't dispatch itself and needs to invoke pending_timer |
| * unconditionally. Note that forced scheduling is likely to induce short |
| * delay before dispatch starts even if @sq->first_pending_disptime is not |
| * in the future and thus shouldn't be used in hot paths. |
| */ |
| static bool throtl_schedule_next_dispatch(struct throtl_service_queue *sq, |
| bool force) |
| { |
| /* any pending children left? */ |
| if (!sq->nr_pending) |
| return true; |
| |
| update_min_dispatch_time(sq); |
| |
| /* is the next dispatch time in the future? */ |
| if (force || time_after(sq->first_pending_disptime, jiffies)) { |
| throtl_schedule_pending_timer(sq, sq->first_pending_disptime); |
| return true; |
| } |
| |
| /* tell the caller to continue dispatching */ |
| return false; |
| } |
| |
| static inline void throtl_start_new_slice(struct throtl_grp *tg, bool rw) |
| { |
| tg->bytes_disp[rw] = 0; |
| tg->io_disp[rw] = 0; |
| tg->slice_start[rw] = jiffies; |
| tg->slice_end[rw] = jiffies + throtl_slice; |
| throtl_log(&tg->service_queue, |
| "[%c] new slice start=%lu end=%lu jiffies=%lu", |
| rw == READ ? 'R' : 'W', tg->slice_start[rw], |
| tg->slice_end[rw], jiffies); |
| } |
| |
| static inline void throtl_set_slice_end(struct throtl_grp *tg, bool rw, |
| unsigned long jiffy_end) |
| { |
| tg->slice_end[rw] = roundup(jiffy_end, throtl_slice); |
| } |
| |
| static inline void throtl_extend_slice(struct throtl_grp *tg, bool rw, |
| unsigned long jiffy_end) |
| { |
| tg->slice_end[rw] = roundup(jiffy_end, throtl_slice); |
| throtl_log(&tg->service_queue, |
| "[%c] extend slice start=%lu end=%lu jiffies=%lu", |
| rw == READ ? 'R' : 'W', tg->slice_start[rw], |
| tg->slice_end[rw], jiffies); |
| } |
| |
| /* Determine if previously allocated or extended slice is complete or not */ |
| static bool throtl_slice_used(struct throtl_grp *tg, bool rw) |
| { |
| if (time_in_range(jiffies, tg->slice_start[rw], tg->slice_end[rw])) |
| return 0; |
| |
| return 1; |
| } |
| |
| /* Trim the used slices and adjust slice start accordingly */ |
| static inline void throtl_trim_slice(struct throtl_grp *tg, bool rw) |
| { |
| unsigned long nr_slices, time_elapsed, io_trim; |
| u64 bytes_trim, tmp; |
| |
| BUG_ON(time_before(tg->slice_end[rw], tg->slice_start[rw])); |
| |
| /* |
| * If bps are unlimited (-1), then time slice don't get |
| * renewed. Don't try to trim the slice if slice is used. A new |
| * slice will start when appropriate. |
| */ |
| if (throtl_slice_used(tg, rw)) |
| return; |
| |
| /* |
| * A bio has been dispatched. Also adjust slice_end. It might happen |
| * that initially cgroup limit was very low resulting in high |
| * slice_end, but later limit was bumped up and bio was dispached |
| * sooner, then we need to reduce slice_end. A high bogus slice_end |
| * is bad because it does not allow new slice to start. |
| */ |
| |
| throtl_set_slice_end(tg, rw, jiffies + throtl_slice); |
| |
| time_elapsed = jiffies - tg->slice_start[rw]; |
| |
| nr_slices = time_elapsed / throtl_slice; |
| |
| if (!nr_slices) |
| return; |
| tmp = tg->bps[rw] * throtl_slice * nr_slices; |
| do_div(tmp, HZ); |
| bytes_trim = tmp; |
| |
| io_trim = (tg->iops[rw] * throtl_slice * nr_slices)/HZ; |
| |
| if (!bytes_trim && !io_trim) |
| return; |
| |
| if (tg->bytes_disp[rw] >= bytes_trim) |
| tg->bytes_disp[rw] -= bytes_trim; |
| else |
| tg->bytes_disp[rw] = 0; |
| |
| if (tg->io_disp[rw] >= io_trim) |
| tg->io_disp[rw] -= io_trim; |
| else |
| tg->io_disp[rw] = 0; |
| |
| tg->slice_start[rw] += nr_slices * throtl_slice; |
| |
| throtl_log(&tg->service_queue, |
| "[%c] trim slice nr=%lu bytes=%llu io=%lu start=%lu end=%lu jiffies=%lu", |
| rw == READ ? 'R' : 'W', nr_slices, bytes_trim, io_trim, |
| tg->slice_start[rw], tg->slice_end[rw], jiffies); |
| } |
| |
| static bool tg_with_in_iops_limit(struct throtl_grp *tg, struct bio *bio, |
| unsigned long *wait) |
| { |
| bool rw = bio_data_dir(bio); |
| unsigned int io_allowed; |
| unsigned long jiffy_elapsed, jiffy_wait, jiffy_elapsed_rnd; |
| u64 tmp; |
| |
| jiffy_elapsed = jiffy_elapsed_rnd = jiffies - tg->slice_start[rw]; |
| |
| /* Slice has just started. Consider one slice interval */ |
| if (!jiffy_elapsed) |
| jiffy_elapsed_rnd = throtl_slice; |
| |
| jiffy_elapsed_rnd = roundup(jiffy_elapsed_rnd, throtl_slice); |
| |
| /* |
| * jiffy_elapsed_rnd should not be a big value as minimum iops can be |
| * 1 then at max jiffy elapsed should be equivalent of 1 second as we |
| * will allow dispatch after 1 second and after that slice should |
| * have been trimmed. |
| */ |
| |
| tmp = (u64)tg->iops[rw] * jiffy_elapsed_rnd; |
| do_div(tmp, HZ); |
| |
| if (tmp > UINT_MAX) |
| io_allowed = UINT_MAX; |
| else |
| io_allowed = tmp; |
| |
| if (tg->io_disp[rw] + 1 <= io_allowed) { |
| if (wait) |
| *wait = 0; |
| return 1; |
| } |
| |
| /* Calc approx time to dispatch */ |
| jiffy_wait = ((tg->io_disp[rw] + 1) * HZ)/tg->iops[rw] + 1; |
| |
| if (jiffy_wait > jiffy_elapsed) |
| jiffy_wait = jiffy_wait - jiffy_elapsed; |
| else |
| jiffy_wait = 1; |
| |
| if (wait) |
| *wait = jiffy_wait; |
| return 0; |
| } |
| |
| static bool tg_with_in_bps_limit(struct throtl_grp *tg, struct bio *bio, |
| unsigned long *wait) |
| { |
| bool rw = bio_data_dir(bio); |
| u64 bytes_allowed, extra_bytes, tmp; |
| unsigned long jiffy_elapsed, jiffy_wait, jiffy_elapsed_rnd; |
| |
| jiffy_elapsed = jiffy_elapsed_rnd = jiffies - tg->slice_start[rw]; |
| |
| /* Slice has just started. Consider one slice interval */ |
| if (!jiffy_elapsed) |
| jiffy_elapsed_rnd = throtl_slice; |
| |
| jiffy_elapsed_rnd = roundup(jiffy_elapsed_rnd, throtl_slice); |
| |
| tmp = tg->bps[rw] * jiffy_elapsed_rnd; |
| do_div(tmp, HZ); |
| bytes_allowed = tmp; |
| |
| if (tg->bytes_disp[rw] + bio->bi_size <= bytes_allowed) { |
| if (wait) |
| *wait = 0; |
| return 1; |
| } |
| |
| /* Calc approx time to dispatch */ |
| extra_bytes = tg->bytes_disp[rw] + bio->bi_size - bytes_allowed; |
| jiffy_wait = div64_u64(extra_bytes * HZ, tg->bps[rw]); |
| |
| if (!jiffy_wait) |
| jiffy_wait = 1; |
| |
| /* |
| * This wait time is without taking into consideration the rounding |
| * up we did. Add that time also. |
| */ |
| jiffy_wait = jiffy_wait + (jiffy_elapsed_rnd - jiffy_elapsed); |
| if (wait) |
| *wait = jiffy_wait; |
| return 0; |
| } |
| |
| static bool tg_no_rule_group(struct throtl_grp *tg, bool rw) { |
| if (tg->bps[rw] == -1 && tg->iops[rw] == -1) |
| return 1; |
| return 0; |
| } |
| |
| /* |
| * Returns whether one can dispatch a bio or not. Also returns approx number |
| * of jiffies to wait before this bio is with-in IO rate and can be dispatched |
| */ |
| static bool tg_may_dispatch(struct throtl_grp *tg, struct bio *bio, |
| unsigned long *wait) |
| { |
| bool rw = bio_data_dir(bio); |
| unsigned long bps_wait = 0, iops_wait = 0, max_wait = 0; |
| |
| /* |
| * Currently whole state machine of group depends on first bio |
| * queued in the group bio list. So one should not be calling |
| * this function with a different bio if there are other bios |
| * queued. |
| */ |
| BUG_ON(tg->service_queue.nr_queued[rw] && |
| bio != throtl_peek_queued(&tg->service_queue.queued[rw])); |
| |
| /* If tg->bps = -1, then BW is unlimited */ |
| if (tg->bps[rw] == -1 && tg->iops[rw] == -1) { |
| if (wait) |
| *wait = 0; |
| return 1; |
| } |
| |
| /* |
| * If previous slice expired, start a new one otherwise renew/extend |
| * existing slice to make sure it is at least throtl_slice interval |
| * long since now. |
| */ |
| if (throtl_slice_used(tg, rw)) |
| throtl_start_new_slice(tg, rw); |
| else { |
| if (time_before(tg->slice_end[rw], jiffies + throtl_slice)) |
| throtl_extend_slice(tg, rw, jiffies + throtl_slice); |
| } |
| |
| if (tg_with_in_bps_limit(tg, bio, &bps_wait) && |
| tg_with_in_iops_limit(tg, bio, &iops_wait)) { |
| if (wait) |
| *wait = 0; |
| return 1; |
| } |
| |
| max_wait = max(bps_wait, iops_wait); |
| |
| if (wait) |
| *wait = max_wait; |
| |
| if (time_before(tg->slice_end[rw], jiffies + max_wait)) |
| throtl_extend_slice(tg, rw, jiffies + max_wait); |
| |
| return 0; |
| } |
| |
| static void throtl_update_dispatch_stats(struct blkcg_gq *blkg, u64 bytes, |
| int rw) |
| { |
| struct throtl_grp *tg = blkg_to_tg(blkg); |
| struct tg_stats_cpu *stats_cpu; |
| unsigned long flags; |
| |
| /* If per cpu stats are not allocated yet, don't do any accounting. */ |
| if (tg->stats_cpu == NULL) |
| return; |
| |
| /* |
| * Disabling interrupts to provide mutual exclusion between two |
| * writes on same cpu. It probably is not needed for 64bit. Not |
| * optimizing that case yet. |
| */ |
| local_irq_save(flags); |
| |
| stats_cpu = this_cpu_ptr(tg->stats_cpu); |
| |
| blkg_rwstat_add(&stats_cpu->serviced, rw, 1); |
| blkg_rwstat_add(&stats_cpu->service_bytes, rw, bytes); |
| |
| local_irq_restore(flags); |
| } |
| |
| static void throtl_charge_bio(struct throtl_grp *tg, struct bio *bio) |
| { |
| bool rw = bio_data_dir(bio); |
| |
| /* Charge the bio to the group */ |
| tg->bytes_disp[rw] += bio->bi_size; |
| tg->io_disp[rw]++; |
| |
| /* |
| * REQ_THROTTLED is used to prevent the same bio to be throttled |
| * more than once as a throttled bio will go through blk-throtl the |
| * second time when it eventually gets issued. Set it when a bio |
| * is being charged to a tg. |
| * |
| * Dispatch stats aren't recursive and each @bio should only be |
| * accounted by the @tg it was originally associated with. Let's |
| * update the stats when setting REQ_THROTTLED for the first time |
| * which is guaranteed to be for the @bio's original tg. |
| */ |
| if (!(bio->bi_rw & REQ_THROTTLED)) { |
| bio->bi_rw |= REQ_THROTTLED; |
| throtl_update_dispatch_stats(tg_to_blkg(tg), bio->bi_size, |
| bio->bi_rw); |
| } |
| } |
| |
| /** |
| * throtl_add_bio_tg - add a bio to the specified throtl_grp |
| * @bio: bio to add |
| * @qn: qnode to use |
| * @tg: the target throtl_grp |
| * |
| * Add @bio to @tg's service_queue using @qn. If @qn is not specified, |
| * tg->qnode_on_self[] is used. |
| */ |
| static void throtl_add_bio_tg(struct bio *bio, struct throtl_qnode *qn, |
| struct throtl_grp *tg) |
| { |
| struct throtl_service_queue *sq = &tg->service_queue; |
| bool rw = bio_data_dir(bio); |
| |
| if (!qn) |
| qn = &tg->qnode_on_self[rw]; |
| |
| /* |
| * If @tg doesn't currently have any bios queued in the same |
| * direction, queueing @bio can change when @tg should be |
| * dispatched. Mark that @tg was empty. This is automatically |
| * cleaered on the next tg_update_disptime(). |
| */ |
| if (!sq->nr_queued[rw]) |
| tg->flags |= THROTL_TG_WAS_EMPTY; |
| |
| throtl_qnode_add_bio(bio, qn, &sq->queued[rw]); |
| |
| sq->nr_queued[rw]++; |
| throtl_enqueue_tg(tg); |
| } |
| |
| static void tg_update_disptime(struct throtl_grp *tg) |
| { |
| struct throtl_service_queue *sq = &tg->service_queue; |
| unsigned long read_wait = -1, write_wait = -1, min_wait = -1, disptime; |
| struct bio *bio; |
| |
| if ((bio = throtl_peek_queued(&sq->queued[READ]))) |
| tg_may_dispatch(tg, bio, &read_wait); |
| |
| if ((bio = throtl_peek_queued(&sq->queued[WRITE]))) |
| tg_may_dispatch(tg, bio, &write_wait); |
| |
| min_wait = min(read_wait, write_wait); |
| disptime = jiffies + min_wait; |
| |
| /* Update dispatch time */ |
| throtl_dequeue_tg(tg); |
| tg->disptime = disptime; |
| throtl_enqueue_tg(tg); |
| |
| /* see throtl_add_bio_tg() */ |
| tg->flags &= ~THROTL_TG_WAS_EMPTY; |
| } |
| |
| static void tg_dispatch_one_bio(struct throtl_grp *tg, bool rw) |
| { |
| struct throtl_service_queue *sq = &tg->service_queue; |
| struct throtl_service_queue *parent_sq = sq->parent_sq; |
| struct throtl_grp *parent_tg = sq_to_tg(parent_sq); |
| struct throtl_grp *tg_to_put = NULL; |
| struct bio *bio; |
| |
| /* |
| * @bio is being transferred from @tg to @parent_sq. Popping a bio |
| * from @tg may put its reference and @parent_sq might end up |
| * getting released prematurely. Remember the tg to put and put it |
| * after @bio is transferred to @parent_sq. |
| */ |
| bio = throtl_pop_queued(&sq->queued[rw], &tg_to_put); |
| sq->nr_queued[rw]--; |
| |
| throtl_charge_bio(tg, bio); |
| |
| /* |
| * If our parent is another tg, we just need to transfer @bio to |
| * the parent using throtl_add_bio_tg(). If our parent is |
| * @td->service_queue, @bio is ready to be issued. Put it on its |
| * bio_lists[] and decrease total number queued. The caller is |
| * responsible for issuing these bios. |
| */ |
| if (parent_tg) { |
| throtl_add_bio_tg(bio, &tg->qnode_on_parent[rw], parent_tg); |
| } else { |
| throtl_qnode_add_bio(bio, &tg->qnode_on_parent[rw], |
| &parent_sq->queued[rw]); |
| BUG_ON(tg->td->nr_queued[rw] <= 0); |
| tg->td->nr_queued[rw]--; |
| } |
| |
| throtl_trim_slice(tg, rw); |
| |
| if (tg_to_put) |
| blkg_put(tg_to_blkg(tg_to_put)); |
| } |
| |
| static int throtl_dispatch_tg(struct throtl_grp *tg) |
| { |
| struct throtl_service_queue *sq = &tg->service_queue; |
| unsigned int nr_reads = 0, nr_writes = 0; |
| unsigned int max_nr_reads = throtl_grp_quantum*3/4; |
| unsigned int max_nr_writes = throtl_grp_quantum - max_nr_reads; |
| struct bio *bio; |
| |
| /* Try to dispatch 75% READS and 25% WRITES */ |
| |
| while ((bio = throtl_peek_queued(&sq->queued[READ])) && |
| tg_may_dispatch(tg, bio, NULL)) { |
| |
| tg_dispatch_one_bio(tg, bio_data_dir(bio)); |
| nr_reads++; |
| |
| if (nr_reads >= max_nr_reads) |
| break; |
| } |
| |
| while ((bio = throtl_peek_queued(&sq->queued[WRITE])) && |
| tg_may_dispatch(tg, bio, NULL)) { |
| |
| tg_dispatch_one_bio(tg, bio_data_dir(bio)); |
| nr_writes++; |
| |
| if (nr_writes >= max_nr_writes) |
| break; |
| } |
| |
| return nr_reads + nr_writes; |
| } |
| |
| static int throtl_select_dispatch(struct throtl_service_queue *parent_sq) |
| { |
| unsigned int nr_disp = 0; |
| |
| while (1) { |
| struct throtl_grp *tg = throtl_rb_first(parent_sq); |
| struct throtl_service_queue *sq = &tg->service_queue; |
| |
| if (!tg) |
| break; |
| |
| if (time_before(jiffies, tg->disptime)) |
| break; |
| |
| throtl_dequeue_tg(tg); |
| |
| nr_disp += throtl_dispatch_tg(tg); |
| |
| if (sq->nr_queued[0] || sq->nr_queued[1]) |
| tg_update_disptime(tg); |
| |
| if (nr_disp >= throtl_quantum) |
| break; |
| } |
| |
| return nr_disp; |
| } |
| |
| /** |
| * throtl_pending_timer_fn - timer function for service_queue->pending_timer |
| * @arg: the throtl_service_queue being serviced |
| * |
| * This timer is armed when a child throtl_grp with active bio's become |
| * pending and queued on the service_queue's pending_tree and expires when |
| * the first child throtl_grp should be dispatched. This function |
| * dispatches bio's from the children throtl_grps to the parent |
| * service_queue. |
| * |
| * If the parent's parent is another throtl_grp, dispatching is propagated |
| * by either arming its pending_timer or repeating dispatch directly. If |
| * the top-level service_tree is reached, throtl_data->dispatch_work is |
| * kicked so that the ready bio's are issued. |
| */ |
| static void throtl_pending_timer_fn(unsigned long arg) |
| { |
| struct throtl_service_queue *sq = (void *)arg; |
| struct throtl_grp *tg = sq_to_tg(sq); |
| struct throtl_data *td = sq_to_td(sq); |
| struct request_queue *q = td->queue; |
| struct throtl_service_queue *parent_sq; |
| bool dispatched; |
| int ret; |
| |
| spin_lock_irq(q->queue_lock); |
| again: |
| parent_sq = sq->parent_sq; |
| dispatched = false; |
| |
| while (true) { |
| throtl_log(sq, "dispatch nr_queued=%u read=%u write=%u", |
| sq->nr_queued[READ] + sq->nr_queued[WRITE], |
| sq->nr_queued[READ], sq->nr_queued[WRITE]); |
| |
| ret = throtl_select_dispatch(sq); |
| if (ret) { |
| throtl_log(sq, "bios disp=%u", ret); |
| dispatched = true; |
| } |
| |
| if (throtl_schedule_next_dispatch(sq, false)) |
| break; |
| |
| /* this dispatch windows is still open, relax and repeat */ |
| spin_unlock_irq(q->queue_lock); |
| cpu_relax(); |
| spin_lock_irq(q->queue_lock); |
| } |
| |
| if (!dispatched) |
| goto out_unlock; |
| |
| if (parent_sq) { |
| /* @parent_sq is another throl_grp, propagate dispatch */ |
| if (tg->flags & THROTL_TG_WAS_EMPTY) { |
| tg_update_disptime(tg); |
| if (!throtl_schedule_next_dispatch(parent_sq, false)) { |
| /* window is already open, repeat dispatching */ |
| sq = parent_sq; |
| tg = sq_to_tg(sq); |
| goto again; |
| } |
| } |
| } else { |
| /* reached the top-level, queue issueing */ |
| queue_work(kthrotld_workqueue, &td->dispatch_work); |
| } |
| out_unlock: |
| spin_unlock_irq(q->queue_lock); |
| } |
| |
| /** |
| * blk_throtl_dispatch_work_fn - work function for throtl_data->dispatch_work |
| * @work: work item being executed |
| * |
| * This function is queued for execution when bio's reach the bio_lists[] |
| * of throtl_data->service_queue. Those bio's are ready and issued by this |
| * function. |
| */ |
| void blk_throtl_dispatch_work_fn(struct work_struct *work) |
| { |
| struct throtl_data *td = container_of(work, struct throtl_data, |
| dispatch_work); |
| struct throtl_service_queue *td_sq = &td->service_queue; |
| struct request_queue *q = td->queue; |
| struct bio_list bio_list_on_stack; |
| struct bio *bio; |
| struct blk_plug plug; |
| int rw; |
| |
| bio_list_init(&bio_list_on_stack); |
| |
| spin_lock_irq(q->queue_lock); |
| for (rw = READ; rw <= WRITE; rw++) |
| while ((bio = throtl_pop_queued(&td_sq->queued[rw], NULL))) |
| bio_list_add(&bio_list_on_stack, bio); |
| spin_unlock_irq(q->queue_lock); |
| |
| if (!bio_list_empty(&bio_list_on_stack)) { |
| blk_start_plug(&plug); |
| while((bio = bio_list_pop(&bio_list_on_stack))) |
| generic_make_request(bio); |
| blk_finish_plug(&plug); |
| } |
| } |
| |
| static u64 tg_prfill_cpu_rwstat(struct seq_file *sf, |
| struct blkg_policy_data *pd, int off) |
| { |
| struct throtl_grp *tg = pd_to_tg(pd); |
| struct blkg_rwstat rwstat = { }, tmp; |
| int i, cpu; |
| |
| for_each_possible_cpu(cpu) { |
| struct tg_stats_cpu *sc = per_cpu_ptr(tg->stats_cpu, cpu); |
| |
| tmp = blkg_rwstat_read((void *)sc + off); |
| for (i = 0; i < BLKG_RWSTAT_NR; i++) |
| rwstat.cnt[i] += tmp.cnt[i]; |
| } |
| |
| return __blkg_prfill_rwstat(sf, pd, &rwstat); |
| } |
| |
| static int tg_print_cpu_rwstat(struct cgroup *cgrp, struct cftype *cft, |
| struct seq_file *sf) |
| { |
| struct blkcg *blkcg = cgroup_to_blkcg(cgrp); |
| |
| blkcg_print_blkgs(sf, blkcg, tg_prfill_cpu_rwstat, &blkcg_policy_throtl, |
| cft->private, true); |
| return 0; |
| } |
| |
| static u64 tg_prfill_conf_u64(struct seq_file *sf, struct blkg_policy_data *pd, |
| int off) |
| { |
| struct throtl_grp *tg = pd_to_tg(pd); |
| u64 v = *(u64 *)((void *)tg + off); |
| |
| if (v == -1) |
| return 0; |
| return __blkg_prfill_u64(sf, pd, v); |
| } |
| |
| static u64 tg_prfill_conf_uint(struct seq_file *sf, struct blkg_policy_data *pd, |
| int off) |
| { |
| struct throtl_grp *tg = pd_to_tg(pd); |
| unsigned int v = *(unsigned int *)((void *)tg + off); |
| |
| if (v == -1) |
| return 0; |
| return __blkg_prfill_u64(sf, pd, v); |
| } |
| |
| static int tg_print_conf_u64(struct cgroup *cgrp, struct cftype *cft, |
| struct seq_file *sf) |
| { |
| blkcg_print_blkgs(sf, cgroup_to_blkcg(cgrp), tg_prfill_conf_u64, |
| &blkcg_policy_throtl, cft->private, false); |
| return 0; |
| } |
| |
| static int tg_print_conf_uint(struct cgroup *cgrp, struct cftype *cft, |
| struct seq_file *sf) |
| { |
| blkcg_print_blkgs(sf, cgroup_to_blkcg(cgrp), tg_prfill_conf_uint, |
| &blkcg_policy_throtl, cft->private, false); |
| return 0; |
| } |
| |
| static int tg_set_conf(struct cgroup *cgrp, struct cftype *cft, const char *buf, |
| bool is_u64) |
| { |
| struct blkcg *blkcg = cgroup_to_blkcg(cgrp); |
| struct blkg_conf_ctx ctx; |
| struct throtl_grp *tg; |
| struct throtl_service_queue *sq; |
| int ret; |
| |
| ret = blkg_conf_prep(blkcg, &blkcg_policy_throtl, buf, &ctx); |
| if (ret) |
| return ret; |
| |
| tg = blkg_to_tg(ctx.blkg); |
| sq = &tg->service_queue; |
| |
| if (!ctx.v) |
| ctx.v = -1; |
| |
| if (is_u64) |
| *(u64 *)((void *)tg + cft->private) = ctx.v; |
| else |
| *(unsigned int *)((void *)tg + cft->private) = ctx.v; |
| |
| throtl_log(&tg->service_queue, |
| "limit change rbps=%llu wbps=%llu riops=%u wiops=%u", |
| tg->bps[READ], tg->bps[WRITE], |
| tg->iops[READ], tg->iops[WRITE]); |
| |
| /* |
| * We're already holding queue_lock and know @tg is valid. Let's |
| * apply the new config directly. |
| * |
| * Restart the slices for both READ and WRITES. It might happen |
| * that a group's limit are dropped suddenly and we don't want to |
| * account recently dispatched IO with new low rate. |
| */ |
| throtl_start_new_slice(tg, 0); |
| throtl_start_new_slice(tg, 1); |
| |
| if (tg->flags & THROTL_TG_PENDING) { |
| tg_update_disptime(tg); |
| throtl_schedule_next_dispatch(sq->parent_sq, true); |
| } |
| |
| blkg_conf_finish(&ctx); |
| return 0; |
| } |
| |
| static int tg_set_conf_u64(struct cgroup *cgrp, struct cftype *cft, |
| const char *buf) |
| { |
| return tg_set_conf(cgrp, cft, buf, true); |
| } |
| |
| static int tg_set_conf_uint(struct cgroup *cgrp, struct cftype *cft, |
| const char *buf) |
| { |
| return tg_set_conf(cgrp, cft, buf, false); |
| } |
| |
| static struct cftype throtl_files[] = { |
| { |
| .name = "throttle.read_bps_device", |
| .private = offsetof(struct throtl_grp, bps[READ]), |
| .read_seq_string = tg_print_conf_u64, |
| .write_string = tg_set_conf_u64, |
| .max_write_len = 256, |
| }, |
| { |
| .name = "throttle.write_bps_device", |
| .private = offsetof(struct throtl_grp, bps[WRITE]), |
| .read_seq_string = tg_print_conf_u64, |
| .write_string = tg_set_conf_u64, |
| .max_write_len = 256, |
| }, |
| { |
| .name = "throttle.read_iops_device", |
| .private = offsetof(struct throtl_grp, iops[READ]), |
| .read_seq_string = tg_print_conf_uint, |
| .write_string = tg_set_conf_uint, |
| .max_write_len = 256, |
| }, |
| { |
| .name = "throttle.write_iops_device", |
| .private = offsetof(struct throtl_grp, iops[WRITE]), |
| .read_seq_string = tg_print_conf_uint, |
| .write_string = tg_set_conf_uint, |
| .max_write_len = 256, |
| }, |
| { |
| .name = "throttle.io_service_bytes", |
| .private = offsetof(struct tg_stats_cpu, service_bytes), |
| .read_seq_string = tg_print_cpu_rwstat, |
| }, |
| { |
| .name = "throttle.io_serviced", |
| .private = offsetof(struct tg_stats_cpu, serviced), |
| .read_seq_string = tg_print_cpu_rwstat, |
| }, |
| { } /* terminate */ |
| }; |
| |
| static void throtl_shutdown_wq(struct request_queue *q) |
| { |
| struct throtl_data *td = q->td; |
| |
| cancel_work_sync(&td->dispatch_work); |
| } |
| |
| static struct blkcg_policy blkcg_policy_throtl = { |
| .pd_size = sizeof(struct throtl_grp), |
| .cftypes = throtl_files, |
| |
| .pd_init_fn = throtl_pd_init, |
| .pd_exit_fn = throtl_pd_exit, |
| .pd_reset_stats_fn = throtl_pd_reset_stats, |
| }; |
| |
| bool blk_throtl_bio(struct request_queue *q, struct bio *bio) |
| { |
| struct throtl_data *td = q->td; |
| struct throtl_qnode *qn = NULL; |
| struct throtl_grp *tg; |
| struct throtl_service_queue *sq; |
| bool rw = bio_data_dir(bio); |
| struct blkcg *blkcg; |
| bool throttled = false; |
| |
| /* see throtl_charge_bio() */ |
| if (bio->bi_rw & REQ_THROTTLED) |
| goto out; |
| |
| /* |
| * A throtl_grp pointer retrieved under rcu can be used to access |
| * basic fields like stats and io rates. If a group has no rules, |
| * just update the dispatch stats in lockless manner and return. |
| */ |
| rcu_read_lock(); |
| blkcg = bio_blkcg(bio); |
| tg = throtl_lookup_tg(td, blkcg); |
| if (tg) { |
| if (tg_no_rule_group(tg, rw)) { |
| throtl_update_dispatch_stats(tg_to_blkg(tg), |
| bio->bi_size, bio->bi_rw); |
| goto out_unlock_rcu; |
| } |
| } |
| |
| /* |
| * Either group has not been allocated yet or it is not an unlimited |
| * IO group |
| */ |
| spin_lock_irq(q->queue_lock); |
| tg = throtl_lookup_create_tg(td, blkcg); |
| if (unlikely(!tg)) |
| goto out_unlock; |
| |
| sq = &tg->service_queue; |
| |
| while (true) { |
| /* throtl is FIFO - if bios are already queued, should queue */ |
| if (sq->nr_queued[rw]) |
| break; |
| |
| /* if above limits, break to queue */ |
| if (!tg_may_dispatch(tg, bio, NULL)) |
| break; |
| |
| /* within limits, let's charge and dispatch directly */ |
| throtl_charge_bio(tg, bio); |
| |
| /* |
| * We need to trim slice even when bios are not being queued |
| * otherwise it might happen that a bio is not queued for |
| * a long time and slice keeps on extending and trim is not |
| * called for a long time. Now if limits are reduced suddenly |
| * we take into account all the IO dispatched so far at new |
| * low rate and * newly queued IO gets a really long dispatch |
| * time. |
| * |
| * So keep on trimming slice even if bio is not queued. |
| */ |
| throtl_trim_slice(tg, rw); |
| |
| /* |
| * @bio passed through this layer without being throttled. |
| * Climb up the ladder. If we''re already at the top, it |
| * can be executed directly. |
| */ |
| qn = &tg->qnode_on_parent[rw]; |
| sq = sq->parent_sq; |
| tg = sq_to_tg(sq); |
| if (!tg) |
| goto out_unlock; |
| } |
| |
| /* out-of-limit, queue to @tg */ |
| throtl_log(sq, "[%c] bio. bdisp=%llu sz=%u bps=%llu iodisp=%u iops=%u queued=%d/%d", |
| rw == READ ? 'R' : 'W', |
| tg->bytes_disp[rw], bio->bi_size, tg->bps[rw], |
| tg->io_disp[rw], tg->iops[rw], |
| sq->nr_queued[READ], sq->nr_queued[WRITE]); |
| |
| bio_associate_current(bio); |
| tg->td->nr_queued[rw]++; |
| throtl_add_bio_tg(bio, qn, tg); |
| throttled = true; |
| |
| /* |
| * Update @tg's dispatch time and force schedule dispatch if @tg |
| * was empty before @bio. The forced scheduling isn't likely to |
| * cause undue delay as @bio is likely to be dispatched directly if |
| * its @tg's disptime is not in the future. |
| */ |
| if (tg->flags & THROTL_TG_WAS_EMPTY) { |
| tg_update_disptime(tg); |
| throtl_schedule_next_dispatch(tg->service_queue.parent_sq, true); |
| } |
| |
| out_unlock: |
| spin_unlock_irq(q->queue_lock); |
| out_unlock_rcu: |
| rcu_read_unlock(); |
| out: |
| /* |
| * As multiple blk-throtls may stack in the same issue path, we |
| * don't want bios to leave with the flag set. Clear the flag if |
| * being issued. |
| */ |
| if (!throttled) |
| bio->bi_rw &= ~REQ_THROTTLED; |
| return throttled; |
| } |
| |
| /* |
| * Dispatch all bios from all children tg's queued on @parent_sq. On |
| * return, @parent_sq is guaranteed to not have any active children tg's |
| * and all bios from previously active tg's are on @parent_sq->bio_lists[]. |
| */ |
| static void tg_drain_bios(struct throtl_service_queue *parent_sq) |
| { |
| struct throtl_grp *tg; |
| |
| while ((tg = throtl_rb_first(parent_sq))) { |
| struct throtl_service_queue *sq = &tg->service_queue; |
| struct bio *bio; |
| |
| throtl_dequeue_tg(tg); |
| |
| while ((bio = throtl_peek_queued(&sq->queued[READ]))) |
| tg_dispatch_one_bio(tg, bio_data_dir(bio)); |
| while ((bio = throtl_peek_queued(&sq->queued[WRITE]))) |
| tg_dispatch_one_bio(tg, bio_data_dir(bio)); |
| } |
| } |
| |
| /** |
| * blk_throtl_drain - drain throttled bios |
| * @q: request_queue to drain throttled bios for |
| * |
| * Dispatch all currently throttled bios on @q through ->make_request_fn(). |
| */ |
| void blk_throtl_drain(struct request_queue *q) |
| __releases(q->queue_lock) __acquires(q->queue_lock) |
| { |
| struct throtl_data *td = q->td; |
| struct blkcg_gq *blkg; |
| struct cgroup *pos_cgrp; |
| struct bio *bio; |
| int rw; |
| |
| queue_lockdep_assert_held(q); |
| rcu_read_lock(); |
| |
| /* |
| * Drain each tg while doing post-order walk on the blkg tree, so |
| * that all bios are propagated to td->service_queue. It'd be |
| * better to walk service_queue tree directly but blkg walk is |
| * easier. |
| */ |
| blkg_for_each_descendant_post(blkg, pos_cgrp, td->queue->root_blkg) |
| tg_drain_bios(&blkg_to_tg(blkg)->service_queue); |
| |
| tg_drain_bios(&td_root_tg(td)->service_queue); |
| |
| /* finally, transfer bios from top-level tg's into the td */ |
| tg_drain_bios(&td->service_queue); |
| |
| rcu_read_unlock(); |
| spin_unlock_irq(q->queue_lock); |
| |
| /* all bios now should be in td->service_queue, issue them */ |
| for (rw = READ; rw <= WRITE; rw++) |
| while ((bio = throtl_pop_queued(&td->service_queue.queued[rw], |
| NULL))) |
| generic_make_request(bio); |
| |
| spin_lock_irq(q->queue_lock); |
| } |
| |
| int blk_throtl_init(struct request_queue *q) |
| { |
| struct throtl_data *td; |
| int ret; |
| |
| td = kzalloc_node(sizeof(*td), GFP_KERNEL, q->node); |
| if (!td) |
| return -ENOMEM; |
| |
| INIT_WORK(&td->dispatch_work, blk_throtl_dispatch_work_fn); |
| throtl_service_queue_init(&td->service_queue, NULL); |
| |
| q->td = td; |
| td->queue = q; |
| |
| /* activate policy */ |
| ret = blkcg_activate_policy(q, &blkcg_policy_throtl); |
| if (ret) |
| kfree(td); |
| return ret; |
| } |
| |
| void blk_throtl_exit(struct request_queue *q) |
| { |
| BUG_ON(!q->td); |
| throtl_shutdown_wq(q); |
| blkcg_deactivate_policy(q, &blkcg_policy_throtl); |
| kfree(q->td); |
| } |
| |
| static int __init throtl_init(void) |
| { |
| kthrotld_workqueue = alloc_workqueue("kthrotld", WQ_MEM_RECLAIM, 0); |
| if (!kthrotld_workqueue) |
| panic("Failed to create kthrotld\n"); |
| |
| return blkcg_policy_register(&blkcg_policy_throtl); |
| } |
| |
| module_init(throtl_init); |