linux-kernel - Re: [PATCH 08/10] provide a version of cpuacct statistics inside cpu cgroup

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Message-ID: <4E8C4AB0.7070008@parallels.com>
Date:	Wed, 5 Oct 2011 16:16:48 +0400
From:	Glauber Costa <glommer@...allels.com>
To:	Peter Zijlstra <a.p.zijlstra@...llo.nl>
CC:	<linux-kernel@...r.kernel.org>, <paul@...lmenage.org>,
	<lizf@...fujitsu.com>, <daniel.lezcano@...e.fr>,
	<jbottomley@...allels.com>, Balbir Singh <bsingharora@...il.com>
Subject: Re: [PATCH 08/10] provide a version of cpuacct statistics inside
 cpu cgroup

On 10/05/2011 01:10 PM, Peter Zijlstra wrote:
> On Sun, 2011-10-02 at 23:21 +0400, Glauber Costa wrote:
>> +       for_each_online_cpu(cpu) {
>> +               struct kernel_stat *kstat = per_cpu_ptr(tg->cpustat, cpu);
>> +               val += kstat->cpustat[USER];
>> +               val += kstat->cpustat[NICE];
>> +       }
>
> by using online_cpu, you fail to sum whatever data was accrued on
> unplugged cpus, is that a problem?
>
>

Humm... I guess it is. We're effectively replacing a percpu_counter, 
that should accumulate anything left in cpus that gets unplugged. I'll
have to change that.

Thanks
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