1 files changed, 25 insertions, 21 deletions

diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index b6491c020f26..f92ba2a869b4 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -532,6 +532,12 @@ static void cfq_add_rq_rb(struct request *rq)
 
         if (!cfq_cfqq_on_rr(cfqq))
                 cfq_add_cfqq_rr(cfqd, cfqq);
+
+        /*
+         * check if this request is a better next-serve candidate
+         */
+        cfqq->next_rq = cfq_choose_req(cfqd, cfqq->next_rq, rq);
+        BUG_ON(!cfqq->next_rq);
 }
 
 static inline void
@@ -986,9 +992,9 @@ __cfq_dispatch_requests(struct cfq_data *cfqd, struct cfq_queue *cfqq,
          * expire an async queue immediately if it has used up its slice. idle
          * queue always expire after 1 dispatch round.
          */
-        if ((!cfq_cfqq_sync(cfqq) &&
+        if (cfqd->busy_queues > 1 && ((!cfq_cfqq_sync(cfqq) &&
             cfqd->dispatch_slice >= cfq_prio_to_maxrq(cfqd, cfqq)) ||
-            cfq_class_idle(cfqq)) {
+            cfq_class_idle(cfqq))) {
                 cfqq->slice_end = jiffies + 1;
                 cfq_slice_expired(cfqd, 0, 0);
         }
@@ -1051,19 +1057,21 @@ cfq_dispatch_requests(request_queue_t *q, int force)
         while ((cfqq = cfq_select_queue(cfqd)) != NULL) {
                 int max_dispatch;
 
-                /*
-                 * Don't repeat dispatch from the previous queue.
-                 */
-                if (prev_cfqq == cfqq)
-                        break;
+                if (cfqd->busy_queues > 1) {
+                        /*
+                         * Don't repeat dispatch from the previous queue.
+                         */
+                        if (prev_cfqq == cfqq)
+                                break;
 
-                /*
-                 * So we have dispatched before in this round, if the
-                 * next queue has idling enabled (must be sync), don't
-                 * allow it service until the previous have continued.
-                 */
-                if (cfqd->rq_in_driver && cfq_cfqq_idle_window(cfqq))
-                        break;
+                        /*
+                         * So we have dispatched before in this round, if the
+                         * next queue has idling enabled (must be sync), don't
+                         * allow it service until the previous have continued.
+                         */
+                        if (cfqd->rq_in_driver && cfq_cfqq_idle_window(cfqq))
+                                break;
+                }
 
                 cfq_clear_cfqq_must_dispatch(cfqq);
                 cfq_clear_cfqq_wait_request(cfqq);
@@ -1370,7 +1378,9 @@ retry:
                 atomic_set(&cfqq->ref, 0);
                 cfqq->cfqd = cfqd;
 
-                cfq_mark_cfqq_idle_window(cfqq);
+                if (key != CFQ_KEY_ASYNC)
+                        cfq_mark_cfqq_idle_window(cfqq);
+
                 cfq_mark_cfqq_prio_changed(cfqq);
                 cfq_mark_cfqq_queue_new(cfqq);
                 cfq_init_prio_data(cfqq);
@@ -1635,12 +1645,6 @@ cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq,
                 cfqq->meta_pending++;
 
         /*
-         * check if this request is a better next-serve candidate)) {
-         */
-        cfqq->next_rq = cfq_choose_req(cfqd, cfqq->next_rq, rq);
-        BUG_ON(!cfqq->next_rq);
-
-        /*
          * we never wait for an async request and we don't allow preemption
          * of an async request. so just return early
          */