From 2c2ea2b1ab411393b92f46b1bfe248b7be307480 Mon Sep 17 00:00:00 2001 From: Chunguang Xu Date: Mon, 2 Aug 2021 11:51:56 +0800 Subject: [PATCH] blk-throtl: optimize IOPS throttle for large IO scenarios [ Upstream commit 4f1e9630afe6332de7286820fedd019f19eac057 ] After patch 54efd50 (block: make generic_make_request handle arbitrarily sized bios), the IO through io-throttle may be larger, and these IOs may be further split into more small IOs. However, IOPS throttle does not seem to be aware of this change, which makes the calculation of IOPS of large IOs incomplete, resulting in disk-side IOPS that does not meet expectations. Maybe we should fix this problem. We can reproduce it by set max_sectors_kb of disk to 128, set blkio.write_iops_throttle to 100, run a dd instance inside blkio and use iostat to watch IOPS: dd if=/dev/zero of=/dev/sdb bs=1M count=1000 oflag=direct As a result, without this change the average IOPS is 1995, with this change the IOPS is 98. Signed-off-by: Chunguang Xu Acked-by: Tejun Heo Link: https://lore.kernel.org/r/65869aaad05475797d63b4c3fed4f529febe3c26.1627876014.git.brookxu@tencent.com Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin --- block/blk-merge.c | 2 ++ block/blk-throttle.c | 32 ++++++++++++++++++++++++++++++++ block/blk.h | 2 ++ 3 files changed, 36 insertions(+) diff --git a/block/blk-merge.c b/block/blk-merge.c index 68d2e330335c..c0a93f282f8c 100644 --- a/block/blk-merge.c +++ b/block/blk-merge.c @@ -373,6 +373,8 @@ void __blk_queue_split(struct bio **bio, unsigned int *nr_segs) #endif /* MY_ABC_HERE */ submit_bio_noacct(*bio); *bio = split; + + blk_throtl_charge_bio_split(*bio); } } diff --git a/block/blk-throttle.c b/block/blk-throttle.c index b771c4299982..63e9d00a0832 100644 --- a/block/blk-throttle.c +++ b/block/blk-throttle.c @@ -178,6 +178,9 @@ struct throtl_grp { unsigned int bad_bio_cnt; /* bios exceeding latency threshold */ unsigned long bio_cnt_reset_time; + atomic_t io_split_cnt[2]; + atomic_t last_io_split_cnt[2]; + struct blkg_rwstat stat_bytes; struct blkg_rwstat stat_ios; }; @@ -771,6 +774,8 @@ static inline void throtl_start_new_slice_with_credit(struct throtl_grp *tg, tg->bytes_disp[rw] = 0; tg->io_disp[rw] = 0; + atomic_set(&tg->io_split_cnt[rw], 0); + /* * Previous slice has expired. We must have trimmed it after last * bio dispatch. That means since start of last slice, we never used @@ -793,6 +798,9 @@ static inline void throtl_start_new_slice(struct throtl_grp *tg, bool rw) tg->io_disp[rw] = 0; tg->slice_start[rw] = jiffies; tg->slice_end[rw] = jiffies + tg->td->throtl_slice; + + atomic_set(&tg->io_split_cnt[rw], 0); + throtl_log(&tg->service_queue, "[%c] new slice start=%lu end=%lu jiffies=%lu", rw == READ ? 'R' : 'W', tg->slice_start[rw], @@ -1025,6 +1033,9 @@ static bool tg_may_dispatch(struct throtl_grp *tg, struct bio *bio, jiffies + tg->td->throtl_slice); } + if (iops_limit != UINT_MAX) + tg->io_disp[rw] += atomic_xchg(&tg->io_split_cnt[rw], 0); + if (tg_with_in_bps_limit(tg, bio, bps_limit, &bps_wait) && tg_with_in_iops_limit(tg, bio, iops_limit, &iops_wait)) { if (wait) @@ -2046,12 +2057,14 @@ static void throtl_downgrade_check(struct throtl_grp *tg) } if (tg->iops[READ][LIMIT_LOW]) { + tg->last_io_disp[READ] += atomic_xchg(&tg->last_io_split_cnt[READ], 0); iops = tg->last_io_disp[READ] * HZ / elapsed_time; if (iops >= tg->iops[READ][LIMIT_LOW]) tg->last_low_overflow_time[READ] = now; } if (tg->iops[WRITE][LIMIT_LOW]) { + tg->last_io_disp[WRITE] += atomic_xchg(&tg->last_io_split_cnt[WRITE], 0); iops = tg->last_io_disp[WRITE] * HZ / elapsed_time; if (iops >= tg->iops[WRITE][LIMIT_LOW]) tg->last_low_overflow_time[WRITE] = now; @@ -2170,6 +2183,25 @@ static inline void throtl_update_latency_buckets(struct throtl_data *td) } #endif +void blk_throtl_charge_bio_split(struct bio *bio) +{ + struct blkcg_gq *blkg = bio->bi_blkg; + struct throtl_grp *parent = blkg_to_tg(blkg); + struct throtl_service_queue *parent_sq; + bool rw = bio_data_dir(bio); + + do { + if (!parent->has_rules[rw]) + break; + + atomic_inc(&parent->io_split_cnt[rw]); + atomic_inc(&parent->last_io_split_cnt[rw]); + + parent_sq = parent->service_queue.parent_sq; + parent = sq_to_tg(parent_sq); + } while (parent); +} + bool blk_throtl_bio(struct bio *bio) { struct request_queue *q = bio->bi_disk->queue; diff --git a/block/blk.h b/block/blk.h index ecfd523c68d0..f84c83300f6f 100644 --- a/block/blk.h +++ b/block/blk.h @@ -299,11 +299,13 @@ int create_task_io_context(struct task_struct *task, gfp_t gfp_mask, int node); extern int blk_throtl_init(struct request_queue *q); extern void blk_throtl_exit(struct request_queue *q); extern void blk_throtl_register_queue(struct request_queue *q); +extern void blk_throtl_charge_bio_split(struct bio *bio); bool blk_throtl_bio(struct bio *bio); #else /* CONFIG_BLK_DEV_THROTTLING */ static inline int blk_throtl_init(struct request_queue *q) { return 0; } static inline void blk_throtl_exit(struct request_queue *q) { } static inline void blk_throtl_register_queue(struct request_queue *q) { } +static inline void blk_throtl_charge_bio_split(struct bio *bio) { } static inline bool blk_throtl_bio(struct bio *bio) { return false; } #endif /* CONFIG_BLK_DEV_THROTTLING */ #ifdef CONFIG_BLK_DEV_THROTTLING_LOW