linux-kernel - [PATCH] sched: fix autogroup nice tune on UP

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Date:	Sun, 23 Jan 2011 23:03:41 +0800
From:	Yong Zhang <yong.zhang0@...il.com>
To:	Peter Zijlstra <a.p.zijlstra@...llo.nl>
Cc:	Michael Witten <mfwitten@...il.com>, linux-kernel@...r.kernel.org,
	Christian Kujau <christian@...dbynature.de>,
	Mike Galbraith <efault@....de>, Ingo Molnar <mingo@...e.hu>
Subject: [PATCH] sched: fix autogroup nice tune on UP

And there is another issue on UP when FAIR_GROUP_SCHED
enabled.

---
From: Yong Zhang <yong.zhang0@...il.com>
Subject: [PATCH] sched: fix autogroup nice tune on UP

When on UP with FAIR_GROUP_SCHED enabled, tune shares
only affect tg->shares, but is not reflected on
tg->se->load, the reason is update_cfs_shares()
do nothing on SMP.
So let sched_group_set_shares() update tg->se->load
directly for UP && FAIR_GROUP_SCHED.

This issue is found when enable autogroup, but also
exists on cgroup.cpu on UP.

Signed-off-by: Yong Zhang <yong.zhang0@...il.com>
Cc: Ingo Molnar <mingo@...e.hu>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Mike Galbraith <efault@....de>
---
 kernel/sched.c |    8 ++++++--
 1 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/kernel/sched.c b/kernel/sched.c
index 3ec2c6c..b8ed459 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -8483,8 +8483,8 @@ static DEFINE_MUTEX(shares_mutex);
 
 int sched_group_set_shares(struct task_group *tg, unsigned long shares)
 {
-	int i;
-	unsigned long flags;
+	int uninitialized_var(i);
+	unsigned long uninitialized_var(flags);
 
 	/*
 	 * We can't change the weight of the root cgroup.
@@ -8502,6 +8502,7 @@ int sched_group_set_shares(struct task_group *tg, unsigned long shares)
 		goto done;
 
 	tg->shares = shares;
+#ifdef CONFIG_SMP
 	for_each_possible_cpu(i) {
 		struct rq *rq = cpu_rq(i);
 		struct sched_entity *se;
@@ -8513,6 +8514,9 @@ int sched_group_set_shares(struct task_group *tg, unsigned long shares)
 			update_cfs_shares(group_cfs_rq(se), 0);
 		raw_spin_unlock_irqrestore(&rq->lock, flags);
 	}
+#else
+	update_load_set(&tg->se[0]->load, shares);
+#endif
 
 done:
 	mutex_unlock(&shares_mutex);
-- 
1.7.1

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