linux-kernel - Re: [PATCH] cpuidle: menu: use nr_running instead of cpuload for calculating perf mult

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Date:	Mon, 04 Jun 2012 12:32:47 +0200
From:	Peter Zijlstra <a.p.zijlstra@...llo.nl>
To:	Vladimir Davydov <vdavydov@...allels.com>
Cc:	Ingo Molnar <mingo@...e.hu>,
	Arjan van de Ven <arjan@...ux.intel.com>,
	Len Brown <lenb@...nel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] cpuidle: menu: use nr_running instead of cpuload for
 calculating perf mult

On Mon, 2012-06-04 at 14:24 +0400, Vladimir Davydov wrote:
> rq->cpuload strongly depends on cgroup hierarchy. For example, if hundreds of
> tasks are running inside cpu:/test cgroup, the sum of cpuload over all cpus
> won't exceed 1024 (by default). That makes the cpuidle menu governor take wrong
> decisions, which can negatively affect overall performance.
> 
> To cope this, use nr_running last seen in __update_cpu_load() instead of
> cpuload for calculating performance multiplier.

What is cpuidle trying to do?
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