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blk-mq: plug request for shared sbitmap

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[ Upstream commit 03f26d8f11403295de445b6e4e0e57ac57755791 ]

In case of shared sbitmap, request won't be held in plug list any more
sine commit 32bc15afed ("blk-mq: Facilitate a shared sbitmap per
tagset"), this way makes request merge from flush plug list & batching
submission not possible, so cause performance regression.

Yanhui reports performance regression when running sequential IO
test(libaio, 16 jobs, 8 depth for each job) in VM, and the VM disk
is emulated with image stored on xfs/megaraid_sas.

Fix the issue by recovering original behavior to allow to hold request
in plug list.

Cc: Yanhui Ma <yama@redhat.com>
Cc: John Garry <john.garry@huawei.com>
Cc: Bart Van Assche <bvanassche@acm.org>
Cc: kashyap.desai@broadcom.com
Fixes: 32bc15afed ("blk-mq: Facilitate a shared sbitmap per tagset")
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20210514022052.1047665-1-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Ming Lei 2021-05-14 10:20:52 +08:00 committed by Greg Kroah-Hartman
parent cde4b55cfb
commit c9c1ed08c1
1 changed files with 3 additions and 2 deletions
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5
block/blk-mq.c
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@ -2203,8 +2203,9 @@ blk_qc_t blk_mq_submit_bio(struct bio *bio)
/* Bypass scheduler for flush requests */
blk_insert_flush(rq);
blk_mq_run_hw_queue(data.hctx, true);
} else if (plug && (q->nr_hw_queues == 1 || q->mq_ops->commit_rqs ||
!blk_queue_nonrot(q))) {
} else if (plug && (q->nr_hw_queues == 1 ||
blk_mq_is_sbitmap_shared(rq->mq_hctx->flags) ||
q->mq_ops->commit_rqs || !blk_queue_nonrot(q))) {
/*
* Use plugging if we have a ->commit_rqs() hook as well, as
* we know the driver uses bd->last in a smart fashion.