linux-kernel - Re: [BUG] cpu controller can't provide fair CPU time for each group

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Date:	Wed, 11 Nov 2009 11:07:28 +0100
From:	Peter Zijlstra <peterz@...radead.org>
To:	Yasunori Goto <y-goto@...fujitsu.com>
Cc:	Miao Xie <miaox@...fujitsu.com>,
	Linux-Kernel <linux-kernel@...r.kernel.org>,
	containers <containers@...ts.linux-foundation.org>,
	Ingo Molnar <mingo@...e.hu>
Subject: Re: [BUG] cpu controller can't provide fair CPU time for each group

On Wed, 2009-11-11 at 15:21 +0900, Yasunori Goto wrote:
> > Someone needs to fix that if they really care.
> 
> To be honest, I don't have any good idea because I'm not familiar with
> schduler's code. 

You could possible try something like the below, its rather gross but
might maybe work,.. has other issues though.


---
 kernel/sched.c |    9 +++++++--
 1 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/kernel/sched.c b/kernel/sched.c
index 91642c1..65629a3 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -1614,7 +1614,7 @@ static void update_group_shares_cpu(struct task_group *tg, int cpu,
  */
 static int tg_shares_up(struct task_group *tg, void *data)
 {
-	unsigned long weight, rq_weight = 0, shares = 0;
+	unsigned long weight, rq_weight = 0, sum_weight = 0, shares = 0;
 	unsigned long *usd_rq_weight;
 	struct sched_domain *sd = data;
 	unsigned long flags;
@@ -1630,6 +1630,7 @@ static int tg_shares_up(struct task_group *tg, void *data)
 		weight = tg->cfs_rq[i]->load.weight;
 		usd_rq_weight[i] = weight;
 
+		rq_weight += weight;
 		/*
 		 * If there are currently no tasks on the cpu pretend there
 		 * is one of average load so that when a new task gets to
@@ -1638,10 +1639,14 @@ static int tg_shares_up(struct task_group *tg, void *data)
 		if (!weight)
 			weight = NICE_0_LOAD;
 
-		rq_weight += weight;
+		sum_weight += weight;
+
 		shares += tg->cfs_rq[i]->shares;
 	}
 
+	if (!rq_weight)
+		rq_weight = sum_weight;
+
 	if ((!shares && rq_weight) || shares > tg->shares)
 		shares = tg->shares;
 

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