Commit db03f88f authored by Ming Lei's avatar Ming Lei Committed by Jens Axboe

blk-mq: insert request not through ->queue_rq into sw/scheduler queue

c616cbee ("blk-mq: punt failed direct issue to dispatch list") supposed
to add request which has been through ->queue_rq() to the hw queue dispatch
list, however it adds request running out of budget or driver tag to hw queue
too. This way basically bypasses request merge, and causes too many request
dispatched to LLD, and system% is unnecessary increased.

Fixes this issue by adding request not through ->queue_rq into sw/scheduler
queue, and this way is safe because no ->queue_rq is called on this request
yet.

High %system can be observed on Azure storvsc device, and even soft lock
is observed. This patch reduces %system during heavy sequential IO,
meantime decreases soft lockup risk.

Fixes: c616cbee ("blk-mq: punt failed direct issue to dispatch list")
Signed-off-by: default avatarMing Lei <ming.lei@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Bart Van Assche <bvanassche@acm.org>
Cc: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 17bc1030
...@@ -2026,7 +2026,8 @@ static blk_status_t __blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx, ...@@ -2026,7 +2026,8 @@ static blk_status_t __blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,
if (bypass_insert) if (bypass_insert)
return BLK_STS_RESOURCE; return BLK_STS_RESOURCE;
blk_mq_request_bypass_insert(rq, false, run_queue); blk_mq_sched_insert_request(rq, false, run_queue, false);
return BLK_STS_OK; return BLK_STS_OK;
} }
......
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