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| author | Zizhi Wo <wozizhi@huawei.com> | 2025-04-17 21:20:52 +0800 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2025-05-05 19:08:34 -0600 |
| commit | f66cf69eb8765341bbeff0e92a7d0d2027f62452 (patch) | |
| tree | e2ec2e263a3bf659f75f13128d406921b8a19087 /block | |
| parent | selftests: ublk: kublk: fix include path (diff) | |
| download | linux-f66cf69eb8765341bbeff0e92a7d0d2027f62452.tar.gz linux-f66cf69eb8765341bbeff0e92a7d0d2027f62452.zip | |
blk-throttle: Fix wrong tg->[bytes/io]_disp update in __tg_update_carryover()
In commit 6cc477c36875 ("blk-throttle: carry over directly"), the carryover
bytes/ios was be carried to [bytes/io]_disp. However, its update mechanism
has some issues.
In __tg_update_carryover(), we calculate "bytes" and "ios" to represent the
carryover, but the computation when updating [bytes/io]_disp is incorrect.
And if the sq->nr_queued is empty, we may not update tg->[bytes/io]_disp to
0 in tg_update_carryover(). We should set it to 0 in non carryover case.
This patch fixes the issue.
Fixes: 6cc477c36875 ("blk-throttle: carry over directly")
Signed-off-by: Zizhi Wo <wozizhi@huawei.com>
Reviewed-by: Yu Kuai <yukuai3@huawei.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20250417132054.2866409-2-wozizhi@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block')
| -rw-r--r-- | block/blk-throttle.c | 22 |
1 files changed, 16 insertions, 6 deletions
diff --git a/block/blk-throttle.c b/block/blk-throttle.c index d6dd2e047874..7437de947120 100644 --- a/block/blk-throttle.c +++ b/block/blk-throttle.c @@ -645,6 +645,18 @@ static void __tg_update_carryover(struct throtl_grp *tg, bool rw, u32 iops_limit = tg_iops_limit(tg, rw); /* + * If the queue is empty, carryover handling is not needed. In such cases, + * tg->[bytes/io]_disp should be reset to 0 to avoid impacting the dispatch + * of subsequent bios. The same handling applies when the previous BPS/IOPS + * limit was set to max. + */ + if (tg->service_queue.nr_queued[rw] == 0) { + tg->bytes_disp[rw] = 0; + tg->io_disp[rw] = 0; + return; + } + + /* * If config is updated while bios are still throttled, calculate and * accumulate how many bytes/ios are waited across changes. And * carryover_bytes/ios will be used to calculate new wait time under new @@ -656,8 +668,8 @@ static void __tg_update_carryover(struct throtl_grp *tg, bool rw, if (iops_limit != UINT_MAX) *ios = calculate_io_allowed(iops_limit, jiffy_elapsed) - tg->io_disp[rw]; - tg->bytes_disp[rw] -= *bytes; - tg->io_disp[rw] -= *ios; + tg->bytes_disp[rw] = -*bytes; + tg->io_disp[rw] = -*ios; } static void tg_update_carryover(struct throtl_grp *tg) @@ -665,10 +677,8 @@ static void tg_update_carryover(struct throtl_grp *tg) long long bytes[2] = {0}; int ios[2] = {0}; - if (tg->service_queue.nr_queued[READ]) - __tg_update_carryover(tg, READ, &bytes[READ], &ios[READ]); - if (tg->service_queue.nr_queued[WRITE]) - __tg_update_carryover(tg, WRITE, &bytes[WRITE], &ios[WRITE]); + __tg_update_carryover(tg, READ, &bytes[READ], &ios[READ]); + __tg_update_carryover(tg, WRITE, &bytes[WRITE], &ios[WRITE]); /* see comments in struct throtl_grp for meaning of these fields. */ throtl_log(&tg->service_queue, "%s: %lld %lld %d %d\n", __func__, |