Re: [PATCH] cpuidle: menu: use nr_running instead of cpuload forcalculating perf mult

From: Vladimir Davydov
Date: Mon Jun 04 2012 - 06:50:36 EST


On 06/04/2012 02:32 PM, Peter Zijlstra wrote:
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?

Basing on cpuload, it selects idle state. The less the load, the lowest the state.
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