Re: [patch v5 09/15] sched: add power aware scheduling infork/exec/wake

From: Peter Zijlstra
Date: Thu Feb 21 2013 - 08:33:18 EST

On Wed, 2013-02-20 at 22:23 +0800, Alex Shi wrote:
> > But but but,... nr_running is completely unrelated to utilization.
> >
> Actually, I also hesitated on the name, how about using nr_running to
> replace group_util directly?

The name is a secondary issue, first you need to explain why you think
nr_running is a useful metric at all.

You can have a high nr_running and a low utilization (a burst of
wakeups, each waking a process that'll instantly go to sleep again), or
low nr_running and high utilization (a single process cpu bound

There is absolutely no relation between utilization and nr_running,
building something on that assumption is just wrong and broken.

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