diff options
author | Yu Kuai <yukuai3@huawei.com> | 2023-08-16 09:27:06 +0800 |
---|---|---|
committer | Jens Axboe <axboe@kernel.dk> | 2023-08-30 10:15:01 -0600 |
commit | bb8d5587bdc3ab211e1eae2eeb966f7a7d1f9c0b (patch) | |
tree | 26600fc57862efddcf1064582086f8a8072d3ad9 /block | |
parent | ef100397fac3e2e403d5d510e66f36e242654073 (diff) |
blk-throttle: fix wrong comparation while 'carryover_ios/bytes' is negative
carryover_ios/bytes[] can be negative in the case that ios are
dispatched in the slice in advance, and then configuration is updated.
For example:
1) set iops limit to 1000, and slice start is 0, slice end is 100ms;
2) current time is 0, and 100 ios are dispatched, those ios will not be
throttled, hence io_disp is 100;
3) still at current time 0, update iops limit to 100, then carryover_ios
is (0 - 100) = -100;
4) then, dispatch a new io at time 0, the expected result is that this
io will wait for 1s. The calculation in tg_within_iops_limit:
io_disp = 0;
io_allowed = calculate_io_allowed + carryover_ios
= 10 + (-100) = -90;
io won't be throttled if (io_disp + 1 < io_allowed) passed.
Before this patch, in step 4) (io_disp + 1 < io_allowed) is passed,
because -90 for unsigned value is very huge, and such io won't be
throttled.
Fix this problem by checking if 'io/bytes_allowed' is negative first.
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20230816012708.1193747-3-yukuai1@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block')
-rw-r--r-- | block/blk-throttle.c | 11 |
1 files changed, 5 insertions, 6 deletions
diff --git a/block/blk-throttle.c b/block/blk-throttle.c index 5184f17f5129..7c93144d03da 100644 --- a/block/blk-throttle.c +++ b/block/blk-throttle.c @@ -825,7 +825,7 @@ static unsigned long tg_within_iops_limit(struct throtl_grp *tg, struct bio *bio u32 iops_limit) { bool rw = bio_data_dir(bio); - unsigned int io_allowed; + int io_allowed; unsigned long jiffy_elapsed, jiffy_wait, jiffy_elapsed_rnd; if (iops_limit == UINT_MAX) { @@ -838,9 +838,8 @@ static unsigned long tg_within_iops_limit(struct throtl_grp *tg, struct bio *bio jiffy_elapsed_rnd = roundup(jiffy_elapsed + 1, tg->td->throtl_slice); io_allowed = calculate_io_allowed(iops_limit, jiffy_elapsed_rnd) + tg->carryover_ios[rw]; - if (tg->io_disp[rw] + 1 <= io_allowed) { + if (io_allowed > 0 && tg->io_disp[rw] + 1 <= io_allowed) return 0; - } /* Calc approx time to dispatch */ jiffy_wait = jiffy_elapsed_rnd - jiffy_elapsed; @@ -851,7 +850,8 @@ static unsigned long tg_within_bps_limit(struct throtl_grp *tg, struct bio *bio, u64 bps_limit) { bool rw = bio_data_dir(bio); - u64 bytes_allowed, extra_bytes; + long long bytes_allowed; + u64 extra_bytes; unsigned long jiffy_elapsed, jiffy_wait, jiffy_elapsed_rnd; unsigned int bio_size = throtl_bio_data_size(bio); @@ -869,9 +869,8 @@ static unsigned long tg_within_bps_limit(struct throtl_grp *tg, struct bio *bio, jiffy_elapsed_rnd = roundup(jiffy_elapsed_rnd, tg->td->throtl_slice); bytes_allowed = calculate_bytes_allowed(bps_limit, jiffy_elapsed_rnd) + tg->carryover_bytes[rw]; - if (tg->bytes_disp[rw] + bio_size <= bytes_allowed) { + if (bytes_allowed > 0 && tg->bytes_disp[rw] + bio_size <= bytes_allowed) return 0; - } /* Calc approx time to dispatch */ extra_bytes = tg->bytes_disp[rw] + bio_size - bytes_allowed; |