| /* |
| * 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; |
| static void throtl_schedule_delayed_work(struct throtl_data *td, |
| unsigned long delay); |
| |
| struct throtl_rb_root { |
| struct rb_root rb; |
| struct rb_node *left; |
| unsigned int count; |
| unsigned long min_disptime; |
| }; |
| |
| #define THROTL_RB_ROOT (struct throtl_rb_root) { .rb = RB_ROOT, .left = NULL, \ |
| .count = 0, .min_disptime = 0} |
| |
| #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_tree member */ |
| struct rb_node rb_node; |
| |
| /* |
| * 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; |
| |
| /* Two lists for READ and WRITE */ |
| struct bio_list bio_lists[2]; |
| |
| /* Number of queued bios on READ and WRITE lists */ |
| unsigned int nr_queued[2]; |
| |
| /* 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]; |
| |
| /* Some throttle limits got updated for the group */ |
| int limits_changed; |
| |
| /* 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_rb_root tg_service_tree; |
| |
| 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 delayed_work throtl_work; |
| |
| int limits_changed; |
| }; |
| |
| /* 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 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); |
| } |
| |
| enum tg_state_flags { |
| THROTL_TG_FLAG_on_rr = 0, /* on round-robin busy list */ |
| }; |
| |
| #define THROTL_TG_FNS(name) \ |
| static inline void throtl_mark_tg_##name(struct throtl_grp *tg) \ |
| { \ |
| (tg)->flags |= (1 << THROTL_TG_FLAG_##name); \ |
| } \ |
| static inline void throtl_clear_tg_##name(struct throtl_grp *tg) \ |
| { \ |
| (tg)->flags &= ~(1 << THROTL_TG_FLAG_##name); \ |
| } \ |
| static inline int throtl_tg_##name(const struct throtl_grp *tg) \ |
| { \ |
| return ((tg)->flags & (1 << THROTL_TG_FLAG_##name)) != 0; \ |
| } |
| |
| THROTL_TG_FNS(on_rr); |
| |
| #define throtl_log_tg(td, tg, fmt, args...) do { \ |
| char __pbuf[128]; \ |
| \ |
| blkg_path(tg_to_blkg(tg), __pbuf, sizeof(__pbuf)); \ |
| blk_add_trace_msg((td)->queue, "throtl %s " fmt, __pbuf, ##args); \ |
| } while (0) |
| |
| #define throtl_log(td, fmt, args...) \ |
| blk_add_trace_msg((td)->queue, "throtl " fmt, ##args) |
| |
| static inline unsigned int total_nr_queued(struct throtl_data *td) |
| { |
| return td->nr_queued[0] + td->nr_queued[1]; |
| } |
| |
| /* |
| * 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_pd_init(struct blkcg_gq *blkg) |
| { |
| struct throtl_grp *tg = blkg_to_tg(blkg); |
| unsigned long flags; |
| |
| RB_CLEAR_NODE(&tg->rb_node); |
| bio_list_init(&tg->bio_lists[0]); |
| bio_list_init(&tg->bio_lists[1]); |
| tg->limits_changed = false; |
| |
| 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); |
| } |
| |
| 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_rb_root *root) |
| { |
| /* Service tree is empty */ |
| if (!root->count) |
| return NULL; |
| |
| if (!root->left) |
| root->left = rb_first(&root->rb); |
| |
| if (root->left) |
| return rb_entry_tg(root->left); |
| |
| 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_rb_root *root) |
| { |
| if (root->left == n) |
| root->left = NULL; |
| rb_erase_init(n, &root->rb); |
| --root->count; |
| } |
| |
| static void update_min_dispatch_time(struct throtl_rb_root *st) |
| { |
| struct throtl_grp *tg; |
| |
| tg = throtl_rb_first(st); |
| if (!tg) |
| return; |
| |
| st->min_disptime = tg->disptime; |
| } |
| |
| static void |
| tg_service_tree_add(struct throtl_rb_root *st, struct throtl_grp *tg) |
| { |
| struct rb_node **node = &st->rb.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) |
| st->left = &tg->rb_node; |
| |
| rb_link_node(&tg->rb_node, parent, node); |
| rb_insert_color(&tg->rb_node, &st->rb); |
| } |
| |
| static void __throtl_enqueue_tg(struct throtl_data *td, struct throtl_grp *tg) |
| { |
| struct throtl_rb_root *st = &td->tg_service_tree; |
| |
| tg_service_tree_add(st, tg); |
| throtl_mark_tg_on_rr(tg); |
| st->count++; |
| } |
| |
| static void throtl_enqueue_tg(struct throtl_data *td, struct throtl_grp *tg) |
| { |
| if (!throtl_tg_on_rr(tg)) |
| __throtl_enqueue_tg(td, tg); |
| } |
| |
| static void __throtl_dequeue_tg(struct throtl_data *td, struct throtl_grp *tg) |
| { |
| throtl_rb_erase(&tg->rb_node, &td->tg_service_tree); |
| throtl_clear_tg_on_rr(tg); |
| } |
| |
| static void throtl_dequeue_tg(struct throtl_data *td, struct throtl_grp *tg) |
| { |
| if (throtl_tg_on_rr(tg)) |
| __throtl_dequeue_tg(td, tg); |
| } |
| |
| static void throtl_schedule_next_dispatch(struct throtl_data *td) |
| { |
| struct throtl_rb_root *st = &td->tg_service_tree; |
| |
| /* |
| * If there are more bios pending, schedule more work. |
| */ |
| if (!total_nr_queued(td)) |
| return; |
| |
| BUG_ON(!st->count); |
| |
| update_min_dispatch_time(st); |
| |
| if (time_before_eq(st->min_disptime, jiffies)) |
| throtl_schedule_delayed_work(td, 0); |
| else |
| throtl_schedule_delayed_work(td, (st->min_disptime - jiffies)); |
| } |
| |
| static inline void |
| throtl_start_new_slice(struct throtl_data *td, 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(td, tg, "[%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_data *td, |
| 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_data *td, |
| struct throtl_grp *tg, bool rw, unsigned long jiffy_end) |
| { |
| tg->slice_end[rw] = roundup(jiffy_end, throtl_slice); |
| throtl_log_tg(td, tg, "[%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_data *td, 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_data *td, 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(td, 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(td, 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(td, tg, "[%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_data *td, 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_data *td, 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_data *td, 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->nr_queued[rw] && bio != bio_list_peek(&tg->bio_lists[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(td, tg, rw)) |
| throtl_start_new_slice(td, tg, rw); |
| else { |
| if (time_before(tg->slice_end[rw], jiffies + throtl_slice)) |
| throtl_extend_slice(td, tg, rw, jiffies + throtl_slice); |
| } |
| |
| if (tg_with_in_bps_limit(td, tg, bio, &bps_wait) |
| && tg_with_in_iops_limit(td, 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(td, 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]++; |
| |
| throtl_update_dispatch_stats(tg_to_blkg(tg), bio->bi_size, bio->bi_rw); |
| } |
| |
| static void throtl_add_bio_tg(struct throtl_data *td, struct throtl_grp *tg, |
| struct bio *bio) |
| { |
| bool rw = bio_data_dir(bio); |
| |
| bio_list_add(&tg->bio_lists[rw], bio); |
| /* Take a bio reference on tg */ |
| blkg_get(tg_to_blkg(tg)); |
| tg->nr_queued[rw]++; |
| td->nr_queued[rw]++; |
| throtl_enqueue_tg(td, tg); |
| } |
| |
| static void tg_update_disptime(struct throtl_data *td, struct throtl_grp *tg) |
| { |
| unsigned long read_wait = -1, write_wait = -1, min_wait = -1, disptime; |
| struct bio *bio; |
| |
| if ((bio = bio_list_peek(&tg->bio_lists[READ]))) |
| tg_may_dispatch(td, tg, bio, &read_wait); |
| |
| if ((bio = bio_list_peek(&tg->bio_lists[WRITE]))) |
| tg_may_dispatch(td, tg, bio, &write_wait); |
| |
| min_wait = min(read_wait, write_wait); |
| disptime = jiffies + min_wait; |
| |
| /* Update dispatch time */ |
| throtl_dequeue_tg(td, tg); |
| tg->disptime = disptime; |
| throtl_enqueue_tg(td, tg); |
| } |
| |
| static void tg_dispatch_one_bio(struct throtl_data *td, struct throtl_grp *tg, |
| bool rw, struct bio_list *bl) |
| { |
| struct bio *bio; |
| |
| bio = bio_list_pop(&tg->bio_lists[rw]); |
| tg->nr_queued[rw]--; |
| /* Drop bio reference on blkg */ |
| blkg_put(tg_to_blkg(tg)); |
| |
| BUG_ON(td->nr_queued[rw] <= 0); |
| td->nr_queued[rw]--; |
| |
| throtl_charge_bio(tg, bio); |
| bio_list_add(bl, bio); |
| bio->bi_rw |= REQ_THROTTLED; |
| |
| throtl_trim_slice(td, tg, rw); |
| } |
| |
| static int throtl_dispatch_tg(struct throtl_data *td, struct throtl_grp *tg, |
| struct bio_list *bl) |
| { |
| 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 = bio_list_peek(&tg->bio_lists[READ])) |
| && tg_may_dispatch(td, tg, bio, NULL)) { |
| |
| tg_dispatch_one_bio(td, tg, bio_data_dir(bio), bl); |
| nr_reads++; |
| |
| if (nr_reads >= max_nr_reads) |
| break; |
| } |
| |
| while ((bio = bio_list_peek(&tg->bio_lists[WRITE])) |
| && tg_may_dispatch(td, tg, bio, NULL)) { |
| |
| tg_dispatch_one_bio(td, tg, bio_data_dir(bio), bl); |
| nr_writes++; |
| |
| if (nr_writes >= max_nr_writes) |
| break; |
| } |
| |
| return nr_reads + nr_writes; |
| } |
| |
| static int throtl_select_dispatch(struct throtl_data *td, struct bio_list *bl) |
| { |
| unsigned int nr_disp = 0; |
| struct throtl_grp *tg; |
| struct throtl_rb_root *st = &td->tg_service_tree; |
| |
| while (1) { |
| tg = throtl_rb_first(st); |
| |
| if (!tg) |
| break; |
| |
| if (time_before(jiffies, tg->disptime)) |
| break; |
| |
| throtl_dequeue_tg(td, tg); |
| |
| nr_disp += throtl_dispatch_tg(td, tg, bl); |
| |
| if (tg->nr_queued[0] || tg->nr_queued[1]) { |
| tg_update_disptime(td, tg); |
| throtl_enqueue_tg(td, tg); |
| } |
| |
| if (nr_disp >= throtl_quantum) |
| break; |
| } |
| |
| return nr_disp; |
| } |
| |
| static void throtl_process_limit_change(struct throtl_data *td) |
| { |
| struct request_queue *q = td->queue; |
| struct blkcg_gq *blkg, *n; |
| |
| if (!td->limits_changed) |
| return; |
| |
| xchg(&td->limits_changed, false); |
| |
| throtl_log(td, "limits changed"); |
| |
| list_for_each_entry_safe(blkg, n, &q->blkg_list, q_node) { |
| struct throtl_grp *tg = blkg_to_tg(blkg); |
| |
| if (!tg->limits_changed) |
| continue; |
| |
| if (!xchg(&tg->limits_changed, false)) |
| continue; |
| |
| throtl_log_tg(td, tg, "limit change rbps=%llu wbps=%llu" |
| " riops=%u wiops=%u", tg->bps[READ], tg->bps[WRITE], |
| tg->iops[READ], tg->iops[WRITE]); |
| |
| /* |
| * 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(td, tg, 0); |
| throtl_start_new_slice(td, tg, 1); |
| |
| if (throtl_tg_on_rr(tg)) |
| tg_update_disptime(td, tg); |
| } |
| } |
| |
| /* Dispatch throttled bios. Should be called without queue lock held. */ |
| static int throtl_dispatch(struct request_queue *q) |
| { |
| struct throtl_data *td = q->td; |
| unsigned int nr_disp = 0; |
| struct bio_list bio_list_on_stack; |
| struct bio *bio; |
| struct blk_plug plug; |
| |
| spin_lock_irq(q->queue_lock); |
| |
| throtl_process_limit_change(td); |
| |
| if (!total_nr_queued(td)) |
| goto out; |
| |
| bio_list_init(&bio_list_on_stack); |
| |
| throtl_log(td, "dispatch nr_queued=%u read=%u write=%u", |
| total_nr_queued(td), td->nr_queued[READ], |
| td->nr_queued[WRITE]); |
| |
| nr_disp = throtl_select_dispatch(td, &bio_list_on_stack); |
| |
| if (nr_disp) |
| throtl_log(td, "bios disp=%u", nr_disp); |
| |
| throtl_schedule_next_dispatch(td); |
| out: |
| spin_unlock_irq(q->queue_lock); |
| |
| /* |
| * If we dispatched some requests, unplug the queue to make sure |
| * immediate dispatch |
| */ |
| if (nr_disp) { |
| blk_start_plug(&plug); |
| while((bio = bio_list_pop(&bio_list_on_stack))) |
| generic_make_request(bio); |
| blk_finish_plug(&plug); |
| } |
| return nr_disp; |
| } |
| |
| void blk_throtl_work(struct work_struct *work) |
| { |
| struct throtl_data *td = container_of(work, struct throtl_data, |
| throtl_work.work); |
| struct request_queue *q = td->queue; |
| |
| throtl_dispatch(q); |
| } |
| |
| /* Call with queue lock held */ |
| static void |
| throtl_schedule_delayed_work(struct throtl_data *td, unsigned long delay) |
| { |
| |
| struct delayed_work *dwork = &td->throtl_work; |
| |
| /* schedule work if limits changed even if no bio is queued */ |
| if (total_nr_queued(td) || td->limits_changed) { |
| mod_delayed_work(kthrotld_workqueue, dwork, delay); |
| throtl_log(td, "schedule work. delay=%lu jiffies=%lu", |
| delay, jiffies); |
| } |
| } |
| |
| 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; |
| |
| if (tg->stats_cpu == NULL) |
| return 0; |
| |
| 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_data *td; |
| int ret; |
| |
| ret = blkg_conf_prep(blkcg, &blkcg_policy_throtl, buf, &ctx); |
| if (ret) |
| return ret; |
| |
| tg = blkg_to_tg(ctx.blkg); |
| td = ctx.blkg->q->td; |
| |
| 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; |
| |
| /* XXX: we don't need the following deferred processing */ |
| xchg(&tg->limits_changed, true); |
| xchg(&td->limits_changed, true); |
| throtl_schedule_delayed_work(td, 0); |
| |
| 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_delayed_work_sync(&td->throtl_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_grp *tg; |
| bool rw = bio_data_dir(bio), update_disptime = true; |
| struct blkcg *blkcg; |
| bool throttled = false; |
| |
| if (bio->bi_rw & REQ_THROTTLED) { |
| 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; |
| |
| if (tg->nr_queued[rw]) { |
| /* |
| * There is already another bio queued in same dir. No |
| * need to update dispatch time. |
| */ |
| update_disptime = false; |
| goto queue_bio; |
| |
| } |
| |
| /* Bio is with-in rate limit of group */ |
| if (tg_may_dispatch(td, tg, bio, NULL)) { |
| 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(td, tg, rw); |
| goto out_unlock; |
| } |
| |
| queue_bio: |
| throtl_log_tg(td, tg, "[%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], |
| tg->nr_queued[READ], tg->nr_queued[WRITE]); |
| |
| bio_associate_current(bio); |
| throtl_add_bio_tg(q->td, tg, bio); |
| throttled = true; |
| |
| if (update_disptime) { |
| tg_update_disptime(td, tg); |
| throtl_schedule_next_dispatch(td); |
| } |
| |
| out_unlock: |
| spin_unlock_irq(q->queue_lock); |
| out_unlock_rcu: |
| rcu_read_unlock(); |
| out: |
| return throttled; |
| } |
| |
| /** |
| * 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 throtl_rb_root *st = &td->tg_service_tree; |
| struct throtl_grp *tg; |
| struct bio_list bl; |
| struct bio *bio; |
| |
| queue_lockdep_assert_held(q); |
| |
| bio_list_init(&bl); |
| |
| while ((tg = throtl_rb_first(st))) { |
| throtl_dequeue_tg(td, tg); |
| |
| while ((bio = bio_list_peek(&tg->bio_lists[READ]))) |
| tg_dispatch_one_bio(td, tg, bio_data_dir(bio), &bl); |
| while ((bio = bio_list_peek(&tg->bio_lists[WRITE]))) |
| tg_dispatch_one_bio(td, tg, bio_data_dir(bio), &bl); |
| } |
| spin_unlock_irq(q->queue_lock); |
| |
| while ((bio = bio_list_pop(&bl))) |
| 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; |
| |
| td->tg_service_tree = THROTL_RB_ROOT; |
| td->limits_changed = false; |
| INIT_DELAYED_WORK(&td->throtl_work, blk_throtl_work); |
| |
| 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); |