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

[Vladimir Davydov]

On Jun 4, 2012, at 5:15 PM, "Arjan van de Ven" <arjan@xxxxxxxxxxxxxxx> wrote:

> On 6/4/2012 3:24 AM, 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.
> 
> nr_running is the wrong answer... it is instantaneous, not longer term.
> cpuidle wants a longer term, per cpu, notion of "busy", to use as proxy
> for performance sensitivity.
> 
> 

I use not the instantaneous nr_running, but nr_running last seen in update_cpu_load() where cpuload[0], which is currently used by cpuidle, is updated.

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/