On 2019/09/27 0:25, Ming Lei wrote: > Some HDD drive may expose multiple hw queue, such as MegraRaid, so > still apply the normal plugging for such devices because sequential IO > may benefit a lot from plug merging. > > Cc: Bart Van Assche <[email protected]> > Cc: Hannes Reinecke <[email protected]> > Cc: Damien Le Moal <[email protected]> > Cc: Dave Chinner <[email protected]> > Signed-off-by: Ming Lei <[email protected]> > --- > block/blk-mq.c | 6 +++++- > 1 file changed, 5 insertions(+), 1 deletion(-) > > diff --git a/block/blk-mq.c b/block/blk-mq.c > index d7aed6518e62..969dfe02fa7c 100644 > --- a/block/blk-mq.c > +++ b/block/blk-mq.c > @@ -1983,10 +1983,14 @@ 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 || q->mq_ops->commit_rqs)) { > + } else if (plug && (q->nr_hw_queues == 1 || q->mq_ops->commit_rqs || > + !blk_queue_nonrot(q))) { > /* > * Use plugging if we have a ->commit_rqs() hook as well, as > * we know the driver uses bd->last in a smart fashion. > + * > + * Use normal plugging if this disk is slow HDD, as sequential > + * IO may benefit a lot from plug merging. > */ > unsigned int request_count = plug->rq_count; > struct request *last = NULL; >
Cc stable needed ? Reviewed-by: Damien Le Moal <[email protected]> -- Damien Le Moal Western Digital Research
