From ec78e8248a229f03b95e5a7609b1ca49023233fa Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <a.p.zijlstra@chello.nl>
Date: Wed, 3 Jun 2009 15:41:20 +0200
Subject: [PATCH] --- yaml --- r: 158333 b: refs/heads/master c:
 e709715915d69b6a929d77e7652c9c3fea61c317 h: refs/heads/master i:   158331:
 47907a6ee37d31f68818c46d753d661f3cb17fbe v: v3

---
 [refs]               |  2 +-
 trunk/kernel/sched.c | 16 ++++++++++++++--
 2 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/[refs] b/[refs]
index 97645e90f81b..13c067e98077 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: a5004278f0525dcb9aa43703ef77bf371ea837cd
+refs/heads/master: e709715915d69b6a929d77e7652c9c3fea61c317
diff --git a/trunk/kernel/sched.c b/trunk/kernel/sched.c
index 26976cd8be0f..ca1f76ba7773 100644
--- a/trunk/kernel/sched.c
+++ b/trunk/kernel/sched.c
@@ -1629,8 +1629,14 @@ static int tg_load_down(struct task_group *tg, void *data)
 
 static void update_shares(struct sched_domain *sd)
 {
-	u64 now = cpu_clock(raw_smp_processor_id());
-	s64 elapsed = now - sd->last_update;
+	s64 elapsed;
+	u64 now;
+
+	if (root_task_group_empty())
+		return;
+
+	now = cpu_clock(raw_smp_processor_id());
+	elapsed = now - sd->last_update;
 
 	if (elapsed >= (s64)(u64)sysctl_sched_shares_ratelimit) {
 		sd->last_update = now;
@@ -1640,6 +1646,9 @@ static void update_shares(struct sched_domain *sd)
 
 static void update_shares_locked(struct rq *rq, struct sched_domain *sd)
 {
+	if (root_task_group_empty())
+		return;
+
 	spin_unlock(&rq->lock);
 	update_shares(sd);
 	spin_lock(&rq->lock);
@@ -1647,6 +1656,9 @@ static void update_shares_locked(struct rq *rq, struct sched_domain *sd)
 
 static void update_h_load(long cpu)
 {
+	if (root_task_group_empty())
+		return;
+
 	walk_tg_tree(tg_load_down, tg_nop, (void *)cpu);
 }