From 408a315356b80a15ab833075f289e7c4bb73a8ed Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <a.p.zijlstra@chello.nl>
Date: Fri, 11 May 2012 00:12:02 +0200
Subject: [PATCH] --- yaml --- r: 305001 b: refs/heads/master c:
 04f733b4afac5dc93ae9b0a8703c60b87def491e h: refs/heads/master i:   304999:
 2d42a2aa8bdec2747c530faef1addc5ae24d75a9 v: v3

---
 [refs]                      |  2 +-
 trunk/include/linux/sched.h |  1 -
 trunk/kernel/sched/core.c   |  2 --
 trunk/kernel/sched/fair.c   | 19 +++++++------------
 4 files changed, 8 insertions(+), 16 deletions(-)

diff --git a/[refs] b/[refs]
index 8a789a43461d..4707cdb8b2d9 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 316ad248307fba13be40f01e92a22b89457c32bc
+refs/heads/master: 04f733b4afac5dc93ae9b0a8703c60b87def491e
diff --git a/trunk/include/linux/sched.h b/trunk/include/linux/sched.h
index 3cbfb55bde25..4a559bf0622f 100644
--- a/trunk/include/linux/sched.h
+++ b/trunk/include/linux/sched.h
@@ -927,7 +927,6 @@ struct sched_group_power {
 struct sched_group {
 	struct sched_group *next;	/* Must be a circular list */
 	atomic_t ref;
-	int balance_cpu;
 
 	unsigned int group_weight;
 	struct sched_group_power *sgp;
diff --git a/trunk/kernel/sched/core.c b/trunk/kernel/sched/core.c
index 0738036fa569..24922b7ff567 100644
--- a/trunk/kernel/sched/core.c
+++ b/trunk/kernel/sched/core.c
@@ -5976,7 +5976,6 @@ build_overlap_sched_groups(struct sched_domain *sd, int cpu)
 
 		sg->sgp = *per_cpu_ptr(sdd->sgp, cpumask_first(sg_span));
 		atomic_inc(&sg->sgp->ref);
-		sg->balance_cpu = -1;
 
 		if (cpumask_test_cpu(cpu, sg_span))
 			groups = sg;
@@ -6052,7 +6051,6 @@ build_sched_groups(struct sched_domain *sd, int cpu)
 
 		cpumask_clear(sched_group_cpus(sg));
 		sg->sgp->power = 0;
-		sg->balance_cpu = -1;
 
 		for_each_cpu(j, span) {
 			if (get_group(j, sdd, NULL) != group)
diff --git a/trunk/kernel/sched/fair.c b/trunk/kernel/sched/fair.c
index 9bd3366dbb1c..a259a614b394 100644
--- a/trunk/kernel/sched/fair.c
+++ b/trunk/kernel/sched/fair.c
@@ -3776,8 +3776,7 @@ static inline void update_sg_lb_stats(struct lb_env *env,
 			int *balance, struct sg_lb_stats *sgs)
 {
 	unsigned long load, max_cpu_load, min_cpu_load, max_nr_running;
-	unsigned int balance_cpu = -1;
-	unsigned long balance_load = ~0UL;
+	unsigned int balance_cpu = -1, first_idle_cpu = 0;
 	unsigned long avg_load_per_task = 0;
 	int i;
 
@@ -3794,11 +3793,12 @@ static inline void update_sg_lb_stats(struct lb_env *env,
 
 		/* Bias balancing toward cpus of our domain */
 		if (local_group) {
-			load = target_load(i, load_idx);
-			if (load < balance_load || idle_cpu(i)) {
-				balance_load = load;
+			if (idle_cpu(i) && !first_idle_cpu) {
+				first_idle_cpu = 1;
 				balance_cpu = i;
 			}
+
+			load = target_load(i, load_idx);
 		} else {
 			load = source_load(i, load_idx);
 			if (load > max_cpu_load) {
@@ -3824,8 +3824,7 @@ static inline void update_sg_lb_stats(struct lb_env *env,
 	 */
 	if (local_group) {
 		if (env->idle != CPU_NEWLY_IDLE) {
-			if (balance_cpu != env->dst_cpu ||
-			    cmpxchg(&group->balance_cpu, -1, balance_cpu) != -1) {
+			if (balance_cpu != env->dst_cpu) {
 				*balance = 0;
 				return;
 			}
@@ -4919,7 +4918,7 @@ static void rebalance_domains(int cpu, enum cpu_idle_type idle)
 	int balance = 1;
 	struct rq *rq = cpu_rq(cpu);
 	unsigned long interval;
-	struct sched_domain *sd, *last = NULL;
+	struct sched_domain *sd;
 	/* Earliest time when we have to do rebalance again */
 	unsigned long next_balance = jiffies + 60*HZ;
 	int update_next_balance = 0;
@@ -4929,7 +4928,6 @@ static void rebalance_domains(int cpu, enum cpu_idle_type idle)
 
 	rcu_read_lock();
 	for_each_domain(cpu, sd) {
-		last = sd;
 		if (!(sd->flags & SD_LOAD_BALANCE))
 			continue;
 
@@ -4974,9 +4972,6 @@ static void rebalance_domains(int cpu, enum cpu_idle_type idle)
 		if (!balance)
 			break;
 	}
-	for (sd = last; sd; sd = sd->child)
-		(void)cmpxchg(&sd->groups->balance_cpu, cpu, -1);
-
 	rcu_read_unlock();
 
 	/*