Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1403788

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

Show all headers | View raw

On Thu, May 19, 2016 at 1:40 PM, Peter Zijlstra <peterz@infradead.org> wrote:
> 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;

I think we need the hints thing for that to be able to distinguish
between RT and the rest.

Also in this particular case it looks like an RT task is the only task
that wakes up often enough and we don't drop the frequency when going
idle.  Do we need a hook somewhere in the idle path?

Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

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

csiph-web