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

From	Peter Zijlstra <peterz@infradead.org>
Newsgroups	linux.kernel
Subject	Re: [RFC PATCH] Increase in idle power with schedutil
Date	2016-05-19 13:50 +0200
Message-ID	<rAuCL-7Be-51@gated-at.bofh.it> (permalink)
References	<rA9eW-2gz-3@gated-at.bofh.it> <rAh2N-7md-1@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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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.

Thread

[RFC PATCH] Increase in idle power with schedutil Shilpasri G Bhat <shilpa.bhat@linux.vnet.ibm.com> - 2016-05-18 15:00 +0200
  [RFC PATCH] cpufreq: powernv: Add fast_switch callback Shilpasri G Bhat <shilpa.bhat@linux.vnet.ibm.com> - 2016-05-18 15:00 +0200
    Re: [RFC PATCH] cpufreq: powernv: Add fast_switch callback "Rafael J. Wysocki" <rafael@kernel.org> - 2016-05-18 23:30 +0200
  Re: [RFC PATCH] Increase in idle power with schedutil "Rafael J. Wysocki" <rafael@kernel.org> - 2016-05-18 23:20 +0200
    Re: [RFC PATCH] Increase in idle power with schedutil Peter Zijlstra <peterz@infradead.org> - 2016-05-19 13:50 +0200
      Re: [RFC PATCH] Increase in idle power with schedutil "Rafael J. Wysocki" <rafael@kernel.org> - 2016-05-19 16:40 +0200
      Re: [RFC PATCH] Increase in idle power with schedutil Shilpasri G Bhat <shilpa.bhat@linux.vnet.ibm.com> - 2016-05-20 15:10 +0200
      Re: [RFC PATCH] Increase in idle power with schedutil Peter Zijlstra <peterz@infradead.org> - 2016-05-22 12:40 +0200
        Re: [RFC PATCH] Increase in idle power with schedutil Steve Muckle <steve.muckle@linaro.org> - 2016-05-22 22:50 +0200
          Re: [RFC PATCH] Increase in idle power with schedutil Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> - 2016-05-23 11:00 +0200
            Re: [RFC PATCH] Increase in idle power with schedutil Peter Zijlstra <peterz@infradead.org> - 2016-05-23 11:30 +0200
          Re: [RFC PATCH] Increase in idle power with schedutil Peter Zijlstra <peterz@infradead.org> - 2016-05-23 11:30 +0200

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