From 4599ea49d4b00a6fbaab2977e7f8359cfc7e8916 Mon Sep 17 00:00:00 2001 From: Baolin Wang Date: Mon, 7 Sep 2020 16:10:16 +0800 Subject: blk-throttle: Avoid calculating bps/iops limitation repeatedly The tg_may_dispatch() will call tg_with_in_bps_limit() and tg_with_in_iops_limit() to check if we can dispatch a bio or not, which will calculate bps/iops limitation multiple times. But tg_may_dispatch() is always called under queue lock, which means the bps/iops limitation will not change in tg_may_dispatch(). So we can calculate the bps/iops limitation only once, and pass them to tg_with_in_bps_limit() and tg_with_in_iops_limit() to avoid calculating bps/iops limitation repeatedly. Signed-off-by: Baolin Wang Signed-off-by: Jens Axboe --- block/blk-throttle.c | 19 ++++++++++--------- 1 file changed, 10 insertions(+), 9 deletions(-) (limited to 'block') diff --git a/block/blk-throttle.c b/block/blk-throttle.c index ca9002d9d2c7..8719e37c3564 100644 --- a/block/blk-throttle.c +++ b/block/blk-throttle.c @@ -894,7 +894,7 @@ static inline void throtl_trim_slice(struct throtl_grp *tg, bool rw) } static bool tg_with_in_iops_limit(struct throtl_grp *tg, struct bio *bio, - unsigned long *wait) + u32 iops_limit, unsigned long *wait) { bool rw = bio_data_dir(bio); unsigned int io_allowed; @@ -913,7 +913,7 @@ static bool tg_with_in_iops_limit(struct throtl_grp *tg, struct bio *bio, * have been trimmed. */ - tmp = (u64)tg_iops_limit(tg, rw) * jiffy_elapsed_rnd; + tmp = (u64)iops_limit * jiffy_elapsed_rnd; do_div(tmp, HZ); if (tmp > UINT_MAX) @@ -936,7 +936,7 @@ static bool tg_with_in_iops_limit(struct throtl_grp *tg, struct bio *bio, } static bool tg_with_in_bps_limit(struct throtl_grp *tg, struct bio *bio, - unsigned long *wait) + u64 bps_limit, unsigned long *wait) { bool rw = bio_data_dir(bio); u64 bytes_allowed, extra_bytes, tmp; @@ -951,7 +951,7 @@ static bool tg_with_in_bps_limit(struct throtl_grp *tg, struct bio *bio, jiffy_elapsed_rnd = roundup(jiffy_elapsed_rnd, tg->td->throtl_slice); - tmp = tg_bps_limit(tg, rw) * jiffy_elapsed_rnd; + tmp = bps_limit * jiffy_elapsed_rnd; do_div(tmp, HZ); bytes_allowed = tmp; @@ -963,7 +963,7 @@ static bool tg_with_in_bps_limit(struct throtl_grp *tg, struct bio *bio, /* Calc approx time to dispatch */ extra_bytes = tg->bytes_disp[rw] + bio_size - bytes_allowed; - jiffy_wait = div64_u64(extra_bytes * HZ, tg_bps_limit(tg, rw)); + jiffy_wait = div64_u64(extra_bytes * HZ, bps_limit); if (!jiffy_wait) jiffy_wait = 1; @@ -987,6 +987,8 @@ static bool tg_may_dispatch(struct throtl_grp *tg, struct bio *bio, { bool rw = bio_data_dir(bio); unsigned long bps_wait = 0, iops_wait = 0, max_wait = 0; + u64 bps_limit = tg_bps_limit(tg, rw); + u32 iops_limit = tg_iops_limit(tg, rw); /* * Currently whole state machine of group depends on first bio @@ -998,8 +1000,7 @@ static bool tg_may_dispatch(struct throtl_grp *tg, struct bio *bio, bio != throtl_peek_queued(&tg->service_queue.queued[rw])); /* If tg->bps = -1, then BW is unlimited */ - if (tg_bps_limit(tg, rw) == U64_MAX && - tg_iops_limit(tg, rw) == UINT_MAX) { + if (bps_limit == U64_MAX && iops_limit == UINT_MAX) { if (wait) *wait = 0; return true; @@ -1021,8 +1022,8 @@ static bool tg_may_dispatch(struct throtl_grp *tg, struct bio *bio, jiffies + tg->td->throtl_slice); } - if (tg_with_in_bps_limit(tg, bio, &bps_wait) && - tg_with_in_iops_limit(tg, bio, &iops_wait)) { + 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) *wait = 0; return true; -- cgit v1.2.3