From b5ce818355a832da2c01add29208135f1b136e84 Mon Sep 17 00:00:00 2001 From: Ming Lei Date: Tue, 18 Aug 2020 17:07:28 +0800 Subject: blk-mq: insert request not through ->queue_rq into sw/scheduler queue [ Upstream commit db03f88fae8a2c8007caafa70287798817df2875 ] c616cbee97ae ("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: c616cbee97ae ("blk-mq: punt failed direct issue to dispatch list") Signed-off-by: Ming Lei Cc: Christoph Hellwig Cc: Bart Van Assche Cc: Mike Snitzer Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin --- block/blk-mq.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/block/blk-mq.c b/block/blk-mq.c index 4e0d173beaa3..e86ccfe37777 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -1909,7 +1909,8 @@ insert: if (bypass_insert) 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; } -- cgit v1.2.3