From db03f88fae8a2c8007caafa70287798817df2875 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 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 --- 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 a80f4986e594..b3d2785eefe9 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -2026,7 +2026,8 @@ 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