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>

1 files changed, 3 insertions, 4 deletions

diff --git a/block/blk-core.c b/block/blk-core.c
index b1fd4f5f07d3..a824e49c0d0a 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -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 @@ get_rq:
         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;