From mboxrd@z Thu Jan 1 00:00:00 1970 From: ming.lei@redhat.com (Ming Lei) Date: Thu, 29 Nov 2018 15:13:23 +0800 Subject: [PATCH 7/7] blk-mq: use plug for devices that implement ->commits_rqs() In-Reply-To: <20181128133538.20329-8-axboe@kernel.dk> References: <20181128133538.20329-1-axboe@kernel.dk> <20181128133538.20329-8-axboe@kernel.dk> Message-ID: <20181129071322.GC27186@ming.t460p> On Wed, Nov 28, 2018@06:35:38AM -0700, Jens Axboe wrote: > If we have that hook, we know the driver handles bd->last == true in > a smart fashion. If it does, even for multiple hardware queues, it's > a good idea to flush batches of requests to the device, if we have > batches of requests from the submitter. > > Signed-off-by: Jens Axboe > --- > block/blk-mq.c | 7 ++++++- > 1 file changed, 6 insertions(+), 1 deletion(-) > > diff --git a/block/blk-mq.c b/block/blk-mq.c > index 9e1045152e45..091557a43d53 100644 > --- a/block/blk-mq.c > +++ b/block/blk-mq.c > @@ -1945,7 +1945,12 @@ static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio) > /* bypass scheduler for flush rq */ > blk_insert_flush(rq); > blk_mq_run_hw_queue(data.hctx, true); > - } else if (plug && q->nr_hw_queues == 1) { > + } else if (plug && (q->nr_hw_queues == 1 || q->mq_ops->commit_rqs)) { > + /* > + * Use plugging if we have a ->commit_rqs() hook as well, > + * as we know the driver uses bd->last in a smart > + * fashion. > + */ > unsigned int request_count = plug->rq_count; > struct request *last = NULL; > > -- > 2.17.1 > Reviewed-by: Ming Lei thanks, Ming