From a12de1d42d74ef3c80e9fb9a2da94daaef747869 Mon Sep 17 00:00:00 2001 From: Ming Lei Date: Fri, 27 Sep 2019 15:24:30 +0800 Subject: blk-mq: honor IO scheduler for multiqueue devices MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit If a device is using multiple queues, the IO scheduler may be bypassed. This may hurt performance for some slow MQ devices, and it also breaks zoned devices which depend on mq-deadline for respecting the write order in one zone. Don't bypass io scheduler if we have one setup. This patch can double sequential write performance basically on MQ scsi_debug when mq-deadline is applied. Cc: Bart Van Assche Cc: Hannes Reinecke Cc: Dave Chinner Reviewed-by: Javier González Reviewed-by: Damien Le Moal Signed-off-by: Ming Lei Signed-off-by: Jens Axboe --- block/blk-mq.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) (limited to 'block/blk-mq.c') diff --git a/block/blk-mq.c b/block/blk-mq.c index 6e3b15f70cd7..5d4bef3c378d 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -2012,6 +2012,8 @@ static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio) } blk_add_rq_to_plug(plug, rq); + } else if (q->elevator) { + blk_mq_sched_insert_request(rq, false, true, true); } else if (plug && !blk_queue_nomerges(q)) { /* * We do limited plugging. If the bio can be merged, do that. @@ -2035,8 +2037,8 @@ static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio) blk_mq_try_issue_directly(data.hctx, same_queue_rq, &cookie); } - } else if ((q->nr_hw_queues > 1 && is_sync) || (!q->elevator && - !data.hctx->dispatch_busy)) { + } else if ((q->nr_hw_queues > 1 && is_sync) || + !data.hctx->dispatch_busy) { blk_mq_try_issue_directly(data.hctx, rq, &cookie); } else { blk_mq_sched_insert_request(rq, false, true, true); -- cgit v1.2.3