diff options
authorMing Lei <ming.lei@redhat.com>2021-05-14 10:20:52 +0800
committerJens Axboe <axboe@kernel.dk>2021-05-14 08:59:08 -0600
commit03f26d8f11403295de445b6e4e0e57ac57755791 (patch)
parent6bdf2fbc48f104a84606f6165aa8a20d9a7d9074 (diff)
blk-mq: plug request for shared sbitmap
In case of shared sbitmap, request won't be held in plug list any more sine commit 32bc15afed04 ("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: 32bc15afed04 ("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>
1 files changed, 3 insertions, 2 deletions
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 466676bc2f0b..28ef0248efba 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -2232,8 +2232,9 @@ blk_qc_t blk_mq_submit_bio(struct bio *bio)
/* Bypass scheduler for flush requests */
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.

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