diff options
| -rw-r--r-- | block/blk-cgroup.c | 6 | ||||
| -rw-r--r-- | block/blk-iocost.c | 23 | ||||
| -rw-r--r-- | include/linux/blk-cgroup.h | 43 |
3 files changed, 48 insertions, 24 deletions
diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c index c5dc833212e1..0a63c6cbbcb1 100644 --- a/block/blk-cgroup.c +++ b/block/blk-cgroup.c @@ -1530,6 +1530,10 @@ static void blkcg_scale_delay(struct blkcg_gq *blkg, u64 now) { u64 old = atomic64_read(&blkg->delay_start); + /* negative use_delay means no scaling, see blkcg_set_delay() */ + if (atomic_read(&blkg->use_delay) < 0) + return; + /* * We only want to scale down every second. The idea here is that we * want to delay people for min(delay_nsec, NSEC_PER_SEC) in a certain @@ -1717,6 +1721,8 @@ void blkcg_schedule_throttle(struct request_queue *q, bool use_memdelay) */ void blkcg_add_delay(struct blkcg_gq *blkg, u64 now, u64 delta) { + if (WARN_ON_ONCE(atomic_read(&blkg->use_delay) < 0)) + return; blkcg_scale_delay(blkg, now); atomic64_add(delta, &blkg->delay_nsec); } diff --git a/block/blk-iocost.c b/block/blk-iocost.c index db35ee682294..a8e99ef76a08 100644 --- a/block/blk-iocost.c +++ b/block/blk-iocost.c @@ -1209,14 +1209,14 @@ static enum hrtimer_restart iocg_waitq_timer_fn(struct hrtimer *timer) return HRTIMER_NORESTART; } -static bool iocg_kick_delay(struct ioc_gq *iocg, struct ioc_now *now, u64 cost) +static bool iocg_kick_delay(struct ioc_gq *iocg, struct ioc_now *now) { struct ioc *ioc = iocg->ioc; struct blkcg_gq *blkg = iocg_to_blkg(iocg); u64 vtime = atomic64_read(&iocg->vtime); u64 vmargin = ioc->margin_us * now->vrate; u64 margin_ns = ioc->margin_us * NSEC_PER_USEC; - u64 expires, oexpires; + u64 delta_ns, expires, oexpires; u32 hw_inuse; /* debt-adjust vtime */ @@ -1233,15 +1233,10 @@ static bool iocg_kick_delay(struct ioc_gq *iocg, struct ioc_now *now, u64 cost) return false; /* use delay */ - if (cost) { - u64 cost_ns = DIV64_U64_ROUND_UP(cost * NSEC_PER_USEC, - now->vrate); - blkcg_add_delay(blkg, now->now_ns, cost_ns); - } - blkcg_use_delay(blkg); - - expires = now->now_ns + DIV64_U64_ROUND_UP(vtime - now->vnow, - now->vrate) * NSEC_PER_USEC; + delta_ns = DIV64_U64_ROUND_UP(vtime - now->vnow, + now->vrate) * NSEC_PER_USEC; + blkcg_set_delay(blkg, delta_ns); + expires = now->now_ns + delta_ns; /* if already active and close enough, don't bother */ oexpires = ktime_to_ns(hrtimer_get_softexpires(&iocg->delay_timer)); @@ -1260,7 +1255,7 @@ static enum hrtimer_restart iocg_delay_timer_fn(struct hrtimer *timer) struct ioc_now now; ioc_now(iocg->ioc, &now); - iocg_kick_delay(iocg, &now, 0); + iocg_kick_delay(iocg, &now); return HRTIMER_NORESTART; } @@ -1378,7 +1373,7 @@ static void ioc_timer_fn(struct timer_list *timer) atomic64_read(&iocg->abs_vdebt)) { /* might be oversleeping vtime / hweight changes, kick */ iocg_kick_waitq(iocg, &now); - iocg_kick_delay(iocg, &now, 0); + iocg_kick_delay(iocg, &now); } else if (iocg_is_idle(iocg)) { /* no waiter and idle, deactivate */ iocg->last_inuse = iocg->inuse; @@ -1737,7 +1732,7 @@ static void ioc_rqos_throttle(struct rq_qos *rqos, struct bio *bio) */ if (bio_issue_as_root_blkg(bio) || fatal_signal_pending(current)) { atomic64_add(abs_cost, &iocg->abs_vdebt); - if (iocg_kick_delay(iocg, &now, cost)) + if (iocg_kick_delay(iocg, &now)) blkcg_schedule_throttle(rqos->q, (bio->bi_opf & REQ_SWAP) == REQ_SWAP); return; diff --git a/include/linux/blk-cgroup.h b/include/linux/blk-cgroup.h index 4deb8bb7b6af..a57ebe2f00ab 100644 --- a/include/linux/blk-cgroup.h +++ b/include/linux/blk-cgroup.h @@ -631,6 +631,8 @@ static inline bool blkcg_bio_issue_check(struct request_queue *q, static inline void blkcg_use_delay(struct blkcg_gq *blkg) { + if (WARN_ON_ONCE(atomic_read(&blkg->use_delay) < 0)) + return; if (atomic_add_return(1, &blkg->use_delay) == 1) atomic_inc(&blkg->blkcg->css.cgroup->congestion_count); } @@ -639,6 +641,8 @@ static inline int blkcg_unuse_delay(struct blkcg_gq *blkg) { int old = atomic_read(&blkg->use_delay); + if (WARN_ON_ONCE(old < 0)) + return 0; if (old == 0) return 0; @@ -663,20 +667,39 @@ static inline int blkcg_unuse_delay(struct blkcg_gq *blkg) return 1; } +/** + * blkcg_set_delay - Enable allocator delay mechanism with the specified delay amount + * @blkg: target blkg + * @delay: delay duration in nsecs + * + * When enabled with this function, the delay is not decayed and must be + * explicitly cleared with blkcg_clear_delay(). Must not be mixed with + * blkcg_[un]use_delay() and blkcg_add_delay() usages. + */ +static inline void blkcg_set_delay(struct blkcg_gq *blkg, u64 delay) +{ + int old = atomic_read(&blkg->use_delay); + + /* We only want 1 person setting the congestion count for this blkg. */ + if (!old && atomic_cmpxchg(&blkg->use_delay, old, -1) == old) + atomic_inc(&blkg->blkcg->css.cgroup->congestion_count); + + atomic64_set(&blkg->delay_nsec, delay); +} + +/** + * blkcg_clear_delay - Disable allocator delay mechanism + * @blkg: target blkg + * + * Disable use_delay mechanism. See blkcg_set_delay(). + */ static inline void blkcg_clear_delay(struct blkcg_gq *blkg) { int old = atomic_read(&blkg->use_delay); - if (!old) - return; + /* We only want 1 person clearing the congestion count for this blkg. */ - while (old) { - int cur = atomic_cmpxchg(&blkg->use_delay, old, 0); - if (cur == old) { - atomic_dec(&blkg->blkcg->css.cgroup->congestion_count); - break; - } - old = cur; - } + if (old && atomic_cmpxchg(&blkg->use_delay, old, 0) == old) + atomic_dec(&blkg->blkcg->css.cgroup->congestion_count); } void blkcg_add_delay(struct blkcg_gq *blkg, u64 now, u64 delta); |