cfq-iosched: tweak the FIFO checking

We currently check the FIFO once per slice. Optimize that a bit and
only do it as the first thing for a new slice, so we don't end up
doing a single request and then seek to the FIFO requests.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

1 files changed, 4 insertions, 3 deletions

diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 3df41a00b553..03b1e474b2bf 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -885,16 +885,17 @@ static inline struct request *cfq_check_fifo(struct cfq_queue *cfqq)
 
         if (cfq_cfqq_fifo_expire(cfqq))
                 return NULL;
+
+        cfq_mark_cfqq_fifo_expire(cfqq);
+
         if (list_empty(&cfqq->fifo))
                 return NULL;
 
         fifo = cfq_cfqq_class_sync(cfqq);
         rq = rq_entry_fifo(cfqq->fifo.next);
 
-        if (time_after(jiffies, rq->start_time + cfqd->cfq_fifo_expire[fifo])) {
-                cfq_mark_cfqq_fifo_expire(cfqq);
+        if (time_after(jiffies, rq->start_time + cfqd->cfq_fifo_expire[fifo]))
                 return rq;
-        }
 
         return NULL;
 }