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block: enabling plugging on SSD devices that don't do queuing

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For the older SSD devices that don't do command queuing, we do want to
enable plugging to get better merging.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Jens Axboe 2009-04-06 14:48:06 +02:00 committed by Linus Torvalds
parent 4194b1eaf1
commit 644b2d99b7
1 changed files with 11 additions and 2 deletions
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13
block/blk-core.c
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@ -1136,6 +1136,15 @@ void init_request_from_bio(struct request *req, struct bio *bio)
blk_rq_bio_prep(req->q, req, bio);
}
/*
* Only disabling plugging for non-rotational devices if it does tagging
* as well, otherwise we do need the proper merging
*/
static inline bool queue_should_plug(struct request_queue *q)
{
return !(blk_queue_nonrot(q) && blk_queue_tagged(q));
}
static int __make_request(struct request_queue *q, struct bio *bio)
{
struct request *req;
@ -1242,11 +1251,11 @@ static int __make_request(struct request_queue *q, struct bio *bio)
if (test_bit(QUEUE_FLAG_SAME_COMP, &q->queue_flags) ||
bio_flagged(bio, BIO_CPU_AFFINE))
req->cpu = blk_cpu_to_group(smp_processor_id());
if (!blk_queue_nonrot(q) && elv_queue_empty(q))
if (queue_should_plug(q) && elv_queue_empty(q))
blk_plug_device(q);
add_request(q, req);
out:
if (unplug || blk_queue_nonrot(q))
if (unplug || !queue_should_plug(q))
__generic_unplug_device(q);
spin_unlock_irq(q->queue_lock);
return 0;