[PATCH] cfq-iosched: non-rot devices do not need queue merging

[Corrado Zoccolo <czoccolo@gmail.com>]

Non rotational devices' performances are not affected by
distance of requests, so there is no point in having overhead
to merge queues of nearby requests.

Signed-off-by: Corrado Zoccolo <czoccolo@gmail.com>
---
 block/cfq-iosched.c |    5 +++--
 1 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 918c7fd..01bb0f3 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -1268,7 +1268,8 @@ static void cfq_prio_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq)
 		return;
 	if (!cfqq->next_rq)
 		return;
-
+	if (blk_queue_nonrot(cfqd->queue))
+		return;
 	cfqq->p_root = &cfqd->prio_trees[cfqq->org_ioprio];
 	__cfqq = cfq_prio_tree_lookup(cfqd, cfqq->p_root,
 				      blk_rq_pos(cfqq->next_rq), &parent, &p);
@@ -1689,7 +1690,7 @@ static struct cfq_queue *cfqq_close(struct cfq_data *cfqd,
 	struct cfq_queue *__cfqq;
 	sector_t sector = cfqd->last_position;
 
-	if (RB_EMPTY_ROOT(root))
+	if (RB_EMPTY_ROOT(root) || blk_queue_nonrot(cfqd->queue))
 		return NULL;
 
 	/*
-- 
1.6.4.4