blk-mq: apply normal plugging for HDD
Some HDD drive may expose multiple hardware queues, such as MegraRaid. Let's apply the normal plugging for such devices because sequential IO may benefit a lot from plug merging. Cc: Bart Van Assche <bvanassche@acm.org> Cc: Hannes Reinecke <hare@suse.com> Cc: Dave Chinner <dchinner@redhat.com> Reviewed-by: Damien Le Moal <damien.lemoal@wdc.com> Signed-off-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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@ -1992,10 +1992,14 @@ static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio)
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/* bypass scheduler for flush rq */
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blk_insert_flush(rq);
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blk_mq_run_hw_queue(data.hctx, true);
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} else if (plug && (q->nr_hw_queues == 1 || q->mq_ops->commit_rqs)) {
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} else if (plug && (q->nr_hw_queues == 1 || q->mq_ops->commit_rqs ||
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!blk_queue_nonrot(q))) {
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/*
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* Use plugging if we have a ->commit_rqs() hook as well, as
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* we know the driver uses bd->last in a smart fashion.
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*
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* Use normal plugging if this disk is slow HDD, as sequential
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* IO may benefit a lot from plug merging.
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*/
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unsigned int request_count = plug->rq_count;
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struct request *last = NULL;
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