From db5896e9cf93f119c0b181c5e6b473d8bf0302e5 Mon Sep 17 00:00:00 2001 From: Kemeng Shi Date: Tue, 18 Oct 2022 19:12:38 +0800 Subject: block: Remove redundant parent blkcg_gp check in check_scale_change Function blkcg_iolatency_throttle will make sure blkg->parent is not NULL before calls check_scale_change. And function check_scale_change is only called in blkcg_iolatency_throttle. Signed-off-by: Kemeng Shi Reviewed-by: Josef Bacik Link: https://lore.kernel.org/r/20221018111240.22612-2-shikemeng@huawei.com Signed-off-by: Jens Axboe --- block/blk-iolatency.c | 3 --- 1 file changed, 3 deletions(-) (limited to 'block/blk-iolatency.c') diff --git a/block/blk-iolatency.c b/block/blk-iolatency.c index 571fa95aafe9..b24d7b788ba3 100644 --- a/block/blk-iolatency.c +++ b/block/blk-iolatency.c @@ -403,9 +403,6 @@ static void check_scale_change(struct iolatency_grp *iolat) u64 scale_lat; int direction = 0; - if (lat_to_blkg(iolat)->parent == NULL) - return; - parent = blkg_to_lat(lat_to_blkg(iolat)->parent); if (!parent) return; -- cgit v1.2.3 From 6891f968985f0569eaf56430518895b3c2885da1 Mon Sep 17 00:00:00 2001 From: Kemeng Shi Date: Tue, 18 Oct 2022 19:12:39 +0800 Subject: block: Correct comment for scale_cookie_change Default queue depth of iolatency_grp is unlimited, so we scale down quickly(once by half) in scale_cookie_change. Remove the "subtract 1/16th" part which is not the truth and add the actual way we scale down. Signed-off-by: Kemeng Shi Link: https://lore.kernel.org/r/20221018111240.22612-3-shikemeng@huawei.com Signed-off-by: Jens Axboe --- block/blk-iolatency.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) (limited to 'block/blk-iolatency.c') diff --git a/block/blk-iolatency.c b/block/blk-iolatency.c index b24d7b788ba3..2c574f98c8d1 100644 --- a/block/blk-iolatency.c +++ b/block/blk-iolatency.c @@ -364,9 +364,11 @@ static void scale_cookie_change(struct blk_iolatency *blkiolat, } /* - * Change the queue depth of the iolatency_grp. We add/subtract 1/16th of the + * Change the queue depth of the iolatency_grp. We add 1/16th of the * queue depth at a time so we don't get wild swings and hopefully dial in to - * fairer distribution of the overall queue depth. + * fairer distribution of the overall queue depth. We halve the queue depth + * at a time so we can scale down queue depth quickly from default unlimited + * to target. */ static void scale_change(struct iolatency_grp *iolat, bool up) { -- cgit v1.2.3 From dc572f418a14b18270676c4a7d23a3c8a5544abc Mon Sep 17 00:00:00 2001 From: Kemeng Shi Date: Tue, 18 Oct 2022 19:12:40 +0800 Subject: block: Replace struct rq_depth with unsigned int in struct iolatency_grp We only need a max queue depth for every iolatency to limit the inflight io number. Replace struct rq_depth with unsigned int to simplfy "struct iolatency_grp" and save memory. Signed-off-by: Kemeng Shi Reviewed-by: Josef Bacik Link: https://lore.kernel.org/r/20221018111240.22612-4-shikemeng@huawei.com Signed-off-by: Jens Axboe --- block/blk-iolatency.c | 28 +++++++++++++--------------- 1 file changed, 13 insertions(+), 15 deletions(-) (limited to 'block/blk-iolatency.c') diff --git a/block/blk-iolatency.c b/block/blk-iolatency.c index 2c574f98c8d1..778a0057193e 100644 --- a/block/blk-iolatency.c +++ b/block/blk-iolatency.c @@ -141,7 +141,7 @@ struct iolatency_grp { struct latency_stat __percpu *stats; struct latency_stat cur_stat; struct blk_iolatency *blkiolat; - struct rq_depth rq_depth; + unsigned int max_depth; struct rq_wait rq_wait; atomic64_t window_start; atomic_t scale_cookie; @@ -280,7 +280,7 @@ static void iolat_cleanup_cb(struct rq_wait *rqw, void *private_data) static bool iolat_acquire_inflight(struct rq_wait *rqw, void *private_data) { struct iolatency_grp *iolat = private_data; - return rq_wait_inc_below(rqw, iolat->rq_depth.max_depth); + return rq_wait_inc_below(rqw, iolat->max_depth); } static void __blkcg_iolatency_throttle(struct rq_qos *rqos, @@ -374,7 +374,7 @@ static void scale_change(struct iolatency_grp *iolat, bool up) { unsigned long qd = iolat->blkiolat->rqos.q->nr_requests; unsigned long scale = scale_amount(qd, up); - unsigned long old = iolat->rq_depth.max_depth; + unsigned long old = iolat->max_depth; if (old > qd) old = qd; @@ -386,12 +386,12 @@ static void scale_change(struct iolatency_grp *iolat, bool up) if (old < qd) { old += scale; old = min(old, qd); - iolat->rq_depth.max_depth = old; + iolat->max_depth = old; wake_up_all(&iolat->rq_wait.wait); } } else { old >>= 1; - iolat->rq_depth.max_depth = max(old, 1UL); + iolat->max_depth = max(old, 1UL); } } @@ -444,7 +444,7 @@ static void check_scale_change(struct iolatency_grp *iolat) } /* We're as low as we can go. */ - if (iolat->rq_depth.max_depth == 1 && direction < 0) { + if (iolat->max_depth == 1 && direction < 0) { blkcg_use_delay(lat_to_blkg(iolat)); return; } @@ -452,7 +452,7 @@ static void check_scale_change(struct iolatency_grp *iolat) /* We're back to the default cookie, unthrottle all the things. */ if (cur_cookie == DEFAULT_SCALE_COOKIE) { blkcg_clear_delay(lat_to_blkg(iolat)); - iolat->rq_depth.max_depth = UINT_MAX; + iolat->max_depth = UINT_MAX; wake_up_all(&iolat->rq_wait.wait); return; } @@ -507,7 +507,7 @@ static void iolatency_record_time(struct iolatency_grp *iolat, * We don't want to count issue_as_root bio's in the cgroups latency * statistics as it could skew the numbers downwards. */ - if (unlikely(issue_as_root && iolat->rq_depth.max_depth != UINT_MAX)) { + if (unlikely(issue_as_root && iolat->max_depth != UINT_MAX)) { u64 sub = iolat->min_lat_nsec; if (req_time < sub) blkcg_add_delay(lat_to_blkg(iolat), now, sub - req_time); @@ -919,7 +919,7 @@ static void iolatency_ssd_stat(struct iolatency_grp *iolat, struct seq_file *s) } preempt_enable(); - if (iolat->rq_depth.max_depth == UINT_MAX) + if (iolat->max_depth == UINT_MAX) seq_printf(s, " missed=%llu total=%llu depth=max", (unsigned long long)stat.ps.missed, (unsigned long long)stat.ps.total); @@ -927,7 +927,7 @@ static void iolatency_ssd_stat(struct iolatency_grp *iolat, struct seq_file *s) seq_printf(s, " missed=%llu total=%llu depth=%u", (unsigned long long)stat.ps.missed, (unsigned long long)stat.ps.total, - iolat->rq_depth.max_depth); + iolat->max_depth); } static void iolatency_pd_stat(struct blkg_policy_data *pd, struct seq_file *s) @@ -944,12 +944,12 @@ static void iolatency_pd_stat(struct blkg_policy_data *pd, struct seq_file *s) avg_lat = div64_u64(iolat->lat_avg, NSEC_PER_USEC); cur_win = div64_u64(iolat->cur_win_nsec, NSEC_PER_MSEC); - if (iolat->rq_depth.max_depth == UINT_MAX) + if (iolat->max_depth == UINT_MAX) seq_printf(s, " depth=max avg_lat=%llu win=%llu", avg_lat, cur_win); else seq_printf(s, " depth=%u avg_lat=%llu win=%llu", - iolat->rq_depth.max_depth, avg_lat, cur_win); + iolat->max_depth, avg_lat, cur_win); } static struct blkg_policy_data *iolatency_pd_alloc(gfp_t gfp, @@ -993,9 +993,7 @@ static void iolatency_pd_init(struct blkg_policy_data *pd) latency_stat_init(iolat, &iolat->cur_stat); rq_wait_init(&iolat->rq_wait); spin_lock_init(&iolat->child_lat.lock); - iolat->rq_depth.queue_depth = blkg->q->nr_requests; - iolat->rq_depth.max_depth = UINT_MAX; - iolat->rq_depth.default_depth = iolat->rq_depth.queue_depth; + iolat->max_depth = UINT_MAX; iolat->blkiolat = blkiolat; iolat->cur_win_nsec = 100 * NSEC_PER_MSEC; atomic64_set(&iolat->window_start, now); -- cgit v1.2.3