Re: CFS Bandwidth Control - Test results of cgroups tasks pinned vsunpinnede

From: Peter Zijlstra
Date: Tue Sep 13 2011 - 10:20:23 EST


On Tue, 2011-09-13 at 09:45 +0530, Srivatsa Vaddagiri wrote:
> * Peter Zijlstra <a.p.zijlstra@xxxxxxxxx> [2011-09-12 14:35:43]:
>
> > Of course it does.. and I bet you can improve that slightly if you
> > manage to fix some of the numerical nightmares that live in the cgroup
> > load-balancer (Paul, care to share your WIP?)
>
> Booting with "nohz=off" also helps significantly.
>
> With nohz=on, average idle time (over 1 min) is 10.3%
> With nohz=off, average idle time (over 1 min) is 3.9%

So we should put the cpufreq/idle governor into the nohz/idle path, it
already tries to predict the idle duration in order to pick a C state,
that same prediction should be used to determine if stopping the tick is
worth it.

This has come up previously, but I can't quite recollect in what
context.
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