diff options
Diffstat (limited to 'block/blk-throttle.c')
| -rw-r--r-- | block/blk-throttle.c | 139 |
1 files changed, 71 insertions, 68 deletions
diff --git a/block/blk-throttle.c b/block/blk-throttle.c index e36cc10a346..5352bdafbcf 100644 --- a/block/blk-throttle.c +++ b/block/blk-throttle.c @@ -102,7 +102,7 @@ struct throtl_data /* Work for dispatching throttled bios */ struct delayed_work throtl_work; - atomic_t limits_changed; + bool limits_changed; }; enum tg_state_flags { @@ -201,6 +201,7 @@ static struct throtl_grp * throtl_find_alloc_tg(struct throtl_data *td, RB_CLEAR_NODE(&tg->rb_node); bio_list_init(&tg->bio_lists[0]); bio_list_init(&tg->bio_lists[1]); + td->limits_changed = false; /* * Take the initial reference that will be released on destroy @@ -737,34 +738,36 @@ static void throtl_process_limit_change(struct throtl_data *td) struct throtl_grp *tg; struct hlist_node *pos, *n; - if (!atomic_read(&td->limits_changed)) + if (!td->limits_changed) return; - throtl_log(td, "limit changed =%d", atomic_read(&td->limits_changed)); + xchg(&td->limits_changed, false); - /* - * Make sure updates from throtl_update_blkio_group_read_bps() group - * of functions to tg->limits_changed are visible. We do not - * want update td->limits_changed to be visible but update to - * tg->limits_changed not being visible yet on this cpu. Hence - * the read barrier. - */ - smp_rmb(); + throtl_log(td, "limits changed"); hlist_for_each_entry_safe(tg, pos, n, &td->tg_list, tg_node) { - if (throtl_tg_on_rr(tg) && tg->limits_changed) { - 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]); + 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); - tg->limits_changed = false; - } } - - smp_mb__before_atomic_dec(); - atomic_dec(&td->limits_changed); - smp_mb__after_atomic_dec(); } /* Dispatch throttled bios. Should be called without queue lock held. */ @@ -774,6 +777,7 @@ static int throtl_dispatch(struct request_queue *q) 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); @@ -802,9 +806,10 @@ out: * immediate dispatch */ if (nr_disp) { + blk_start_plug(&plug); while((bio = bio_list_pop(&bio_list_on_stack))) generic_make_request(bio); - blk_unplug(q); + blk_finish_plug(&plug); } return nr_disp; } @@ -825,7 +830,8 @@ throtl_schedule_delayed_work(struct throtl_data *td, unsigned long delay) struct delayed_work *dwork = &td->throtl_work; - if (total_nr_queued(td) > 0) { + /* schedule work if limits changed even if no bio is queued */ + if (total_nr_queued(td) > 0 || td->limits_changed) { /* * We might have a work scheduled to be executed in future. * Cancel that and schedule a new one. @@ -898,6 +904,15 @@ void throtl_unlink_blkio_group(void *key, struct blkio_group *blkg) spin_unlock_irqrestore(td->queue->queue_lock, flags); } +static void throtl_update_blkio_group_common(struct throtl_data *td, + struct throtl_grp *tg) +{ + xchg(&tg->limits_changed, true); + xchg(&td->limits_changed, true); + /* Schedule a work now to process the limit change */ + throtl_schedule_delayed_work(td, 0); +} + /* * For all update functions, key should be a valid pointer because these * update functions are called under blkcg_lock, that means, blkg is @@ -911,64 +926,43 @@ static void throtl_update_blkio_group_read_bps(void *key, struct blkio_group *blkg, u64 read_bps) { struct throtl_data *td = key; + struct throtl_grp *tg = tg_of_blkg(blkg); - tg_of_blkg(blkg)->bps[READ] = read_bps; - /* Make sure read_bps is updated before setting limits_changed */ - smp_wmb(); - tg_of_blkg(blkg)->limits_changed = true; - - /* Make sure tg->limits_changed is updated before td->limits_changed */ - smp_mb__before_atomic_inc(); - atomic_inc(&td->limits_changed); - smp_mb__after_atomic_inc(); - - /* Schedule a work now to process the limit change */ - throtl_schedule_delayed_work(td, 0); + tg->bps[READ] = read_bps; + throtl_update_blkio_group_common(td, tg); } static void throtl_update_blkio_group_write_bps(void *key, struct blkio_group *blkg, u64 write_bps) { struct throtl_data *td = key; + struct throtl_grp *tg = tg_of_blkg(blkg); - tg_of_blkg(blkg)->bps[WRITE] = write_bps; - smp_wmb(); - tg_of_blkg(blkg)->limits_changed = true; - smp_mb__before_atomic_inc(); - atomic_inc(&td->limits_changed); - smp_mb__after_atomic_inc(); - throtl_schedule_delayed_work(td, 0); + tg->bps[WRITE] = write_bps; + throtl_update_blkio_group_common(td, tg); } static void throtl_update_blkio_group_read_iops(void *key, struct blkio_group *blkg, unsigned int read_iops) { struct throtl_data *td = key; + struct throtl_grp *tg = tg_of_blkg(blkg); - tg_of_blkg(blkg)->iops[READ] = read_iops; - smp_wmb(); - tg_of_blkg(blkg)->limits_changed = true; - smp_mb__before_atomic_inc(); - atomic_inc(&td->limits_changed); - smp_mb__after_atomic_inc(); - throtl_schedule_delayed_work(td, 0); + tg->iops[READ] = read_iops; + throtl_update_blkio_group_common(td, tg); } static void throtl_update_blkio_group_write_iops(void *key, struct blkio_group *blkg, unsigned int write_iops) { struct throtl_data *td = key; + struct throtl_grp *tg = tg_of_blkg(blkg); - tg_of_blkg(blkg)->iops[WRITE] = write_iops; - smp_wmb(); - tg_of_blkg(blkg)->limits_changed = true; - smp_mb__before_atomic_inc(); - atomic_inc(&td->limits_changed); - smp_mb__after_atomic_inc(); - throtl_schedule_delayed_work(td, 0); + tg->iops[WRITE] = write_iops; + throtl_update_blkio_group_common(td, tg); } -void throtl_shutdown_timer_wq(struct request_queue *q) +static void throtl_shutdown_wq(struct request_queue *q) { struct throtl_data *td = q->td; @@ -1009,20 +1003,28 @@ int blk_throtl_bio(struct request_queue *q, struct bio **biop) /* * There is already another bio queued in same dir. No * need to update dispatch time. - * Still update the disptime if rate limits on this group - * were changed. */ - if (!tg->limits_changed) - update_disptime = false; - else - tg->limits_changed = false; - + 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; } @@ -1058,7 +1060,7 @@ int blk_throtl_init(struct request_queue *q) INIT_HLIST_HEAD(&td->tg_list); td->tg_service_tree = THROTL_RB_ROOT; - atomic_set(&td->limits_changed, 0); + td->limits_changed = false; /* Init root group */ tg = &td->root_tg; @@ -1070,6 +1072,7 @@ int blk_throtl_init(struct request_queue *q) /* Practically unlimited BW */ tg->bps[0] = tg->bps[1] = -1; tg->iops[0] = tg->iops[1] = -1; + td->limits_changed = false; /* * Set root group reference to 2. One reference will be dropped when @@ -1102,7 +1105,7 @@ void blk_throtl_exit(struct request_queue *q) BUG_ON(!td); - throtl_shutdown_timer_wq(q); + throtl_shutdown_wq(q); spin_lock_irq(q->queue_lock); throtl_release_tgs(td); @@ -1132,7 +1135,7 @@ void blk_throtl_exit(struct request_queue *q) * update limits through cgroup and another work got queued, cancel * it. */ - throtl_shutdown_timer_wq(q); + throtl_shutdown_wq(q); throtl_td_free(td); } |