From 1332559d815f1ce55ebe66d5c8c14f5b47edd42d Mon Sep 17 00:00:00 2001
From: Corrado Zoccolo <czoccolo@gmail.com>
Date: Mon, 26 Oct 2009 22:45:11 +0100
Subject: [PATCH] --- yaml --- r: 172926 b: refs/heads/master c:
 a6d44e982d3734583b3b4e1d36921af8cfd61fc0 h: refs/heads/master v: v3

---
 [refs]                    |  2 +-
 trunk/block/cfq-iosched.c | 34 +++++++++++++++++++++++++++++++---
 2 files changed, 32 insertions(+), 4 deletions(-)

diff --git a/[refs] b/[refs]
index 4d356f5061ff..0265dfd198aa 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: c0324a020e5b351f100569b128715985f1023af8
+refs/heads/master: a6d44e982d3734583b3b4e1d36921af8cfd61fc0
diff --git a/trunk/block/cfq-iosched.c b/trunk/block/cfq-iosched.c
index 6e5c3d715ebe..76afa3696894 100644
--- a/trunk/block/cfq-iosched.c
+++ b/trunk/block/cfq-iosched.c
@@ -1160,6 +1160,34 @@ static struct cfq_queue *cfq_close_cooperator(struct cfq_data *cfqd,
 	return cfqq;
 }
 
+/*
+ * Determine whether we should enforce idle window for this queue.
+ */
+
+static bool cfq_should_idle(struct cfq_data *cfqd, struct cfq_queue *cfqq)
+{
+	enum wl_prio_t prio = cfqq_prio(cfqq);
+	struct cfq_rb_root *service_tree;
+
+	/* We never do for idle class queues. */
+	if (prio == IDLE_WORKLOAD)
+		return false;
+
+	/* We do for queues that were marked with idle window flag. */
+	if (cfq_cfqq_idle_window(cfqq))
+		return true;
+
+	/*
+	 * Otherwise, we do only if they are the last ones
+	 * in their service tree.
+	 */
+	service_tree = service_tree_for(prio, cfqd);
+	if (service_tree->count == 0)
+		return true;
+
+	return (service_tree->count == 1 && cfq_rb_first(service_tree) == cfqq);
+}
+
 static void cfq_arm_slice_timer(struct cfq_data *cfqd)
 {
 	struct cfq_queue *cfqq = cfqd->active_queue;
@@ -1180,7 +1208,7 @@ static void cfq_arm_slice_timer(struct cfq_data *cfqd)
 	/*
 	 * idle is disabled, either manually or by past process history
 	 */
-	if (!cfqd->cfq_slice_idle || !cfq_cfqq_idle_window(cfqq))
+	if (!cfqd->cfq_slice_idle || !cfq_should_idle(cfqd, cfqq))
 		return;
 
 	/*
@@ -1362,7 +1390,7 @@ static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd)
 	 * conditions to happen (or time out) before selecting a new queue.
 	 */
 	if (timer_pending(&cfqd->idle_slice_timer) ||
-	    (cfqq->dispatched && cfq_cfqq_idle_window(cfqq))) {
+	    (cfqq->dispatched && cfq_should_idle(cfqd, cfqq))) {
 		cfqq = NULL;
 		goto keep_queue;
 	}
@@ -1427,7 +1455,7 @@ static bool cfq_may_dispatch(struct cfq_data *cfqd, struct cfq_queue *cfqq)
 	/*
 	 * Drain async requests before we start sync IO
 	 */
-	if (cfq_cfqq_idle_window(cfqq) && cfqd->rq_in_driver[BLK_RW_ASYNC])
+	if (cfq_should_idle(cfqd, cfqq) && cfqd->rq_in_driver[BLK_RW_ASYNC])
 		return false;
 
 	/*