block: don't use plugging on SSD devices

We just want to hand the first bits of IO to the device as fast
as possible. Gains a few percent on the IOPS rate.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
This commit is contained in:
Jens Axboe 2008-10-17 13:58:29 +02:00
parent a185eb4bc8
commit a31a97381c

View file

@ -268,8 +268,7 @@ void __generic_unplug_device(struct request_queue *q)
{
if (unlikely(blk_queue_stopped(q)))
return;
if (!blk_remove_plug(q))
if (!blk_remove_plug(q) && !blk_queue_nonrot(q))
return;
q->request_fn(q);
@ -1241,11 +1240,11 @@ 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 (elv_queue_empty(q))
if (!blk_queue_nonrot(q) && elv_queue_empty(q))
blk_plug_device(q);
add_request(q, req);
out:
if (sync)
if (sync || blk_queue_nonrot(q))
__generic_unplug_device(q);
spin_unlock_irq(q->queue_lock);
return 0;