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>
diff --git a/block/blk-core.c b/block/blk-core.c
index b1fd4f5..a824e49 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -268,8 +268,7 @@
{
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 @@
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;
