Re: [RFC PATCH] Increase in idle power with schedutil

Peter Zijlstra
2016-05-19T11:40:38Z

On Wed, May 18, 2016 at 11:11:51PM +0200, Rafael J. Wysocki wrote:
> On Wed, May 18, 2016 at 2:53 PM, Shilpasri G Bhat
> <shilpa.bhat@linux.vnet.ibm.com> wrote:
> > This patch adds driver callback for fast_switch and below observations
> > on schedutil governor are done with this patch.
> >
> > In POWER8 there is a regression observed with schedutil compared to
> > ondemand. With schedutil the frequency is not ramping down and is
> > mostly stuck at max frequency during idle . This is because of the
> > watchdog timer, an RT task which is fired every 4 seconds which
> > results in requesting max frequency.
>
> Well, yes, that would be problematic.
>

Right; we need to come up with something for RT tasks; but what happens
if you disable the watchdog? This should be entirely doable and might
give a better comparison.