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| author | Kemeng Shi <shikemeng@huawei.com> | 2022-12-05 12:57:02 +0100 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2022-12-05 21:44:27 +0100 |
| commit | 84aca0a7e039c8735abc0f89f3f48e9006c0dfc7 (patch) | |
| tree | 2c558db44b8ff430c08d41a8f92f3789e7eb99d6 /block/blk-throttle.c | |
| parent | blk-throttle: correct stale comment in throtl_pd_init (diff) | |
| download | linux-84aca0a7e039c8735abc0f89f3f48e9006c0dfc7.tar.xz linux-84aca0a7e039c8735abc0f89f3f48e9006c0dfc7.zip | |
blk-throttle: Fix that bps of child could exceed bps limited in parent
Consider situation as following (on the default hierarchy):
HDD
|
root (bps limit: 4k)
|
child (bps limit :8k)
|
fio bs=8k
Rate of fio is supposed to be 4k, but result is 8k. Reason is as
following:
Size of single IO from fio is larger than bytes allowed in one
throtl_slice in child, so IOs are always queued in child group first.
When queued IOs in child are dispatched to parent group, BIO_BPS_THROTTLED
is set and these IOs will not be limited by tg_within_bps_limit anymore.
Fix this by only set BIO_BPS_THROTTLED when the bio traversed the entire
tree.
There patch has no influence on situation which is not on the default
hierarchy as each group is a single root group without parent.
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Kemeng Shi <shikemeng@huawei.com>
Link: https://lore.kernel.org/r/20221205115709.251489-3-shikemeng@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block/blk-throttle.c')
| -rw-r--r-- | block/blk-throttle.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/block/blk-throttle.c b/block/blk-throttle.c index 8e2349b17936..2444ebf5f11d 100644 --- a/block/blk-throttle.c +++ b/block/blk-throttle.c @@ -1067,7 +1067,6 @@ static void tg_dispatch_one_bio(struct throtl_grp *tg, bool rw) sq->nr_queued[rw]--; throtl_charge_bio(tg, bio); - bio_set_flag(bio, BIO_BPS_THROTTLED); /* * If our parent is another tg, we just need to transfer @bio to @@ -1080,6 +1079,7 @@ static void tg_dispatch_one_bio(struct throtl_grp *tg, bool rw) throtl_add_bio_tg(bio, &tg->qnode_on_parent[rw], parent_tg); start_parent_slice_with_credit(tg, parent_tg, rw); } else { + bio_set_flag(bio, BIO_BPS_THROTTLED); throtl_qnode_add_bio(bio, &tg->qnode_on_parent[rw], &parent_sq->queued[rw]); BUG_ON(tg->td->nr_queued[rw] <= 0); |