Re: [PATCH 1/4] sched: Don't account tickless CPU load on tick

From	Byungchul Park <byungchul.park@lge.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH 1/4] sched: Don't account tickless CPU load on tick
Date	2016-02-02 02:00 +0100
Message-ID	<qXxu2-2HC-3@gated-at.bofh.it> (permalink)
References	(5 earlier) <qSYbx-51L-33@gated-at.bofh.it> <qVXiW-5U4-7@gated-at.bofh.it> <qWe0q-OA-17@gated-at.bofh.it> <qXjAL-11X-13@gated-at.bofh.it> <qXk3L-1dK-13@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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On Mon, Feb 01, 2016 at 11:34:33AM +0100, Peter Zijlstra wrote:
> On Mon, Feb 01, 2016 at 07:05:13PM +0900, Byungchul Park wrote:
> > On Fri, Jan 29, 2016 at 10:50:16AM +0100, Peter Zijlstra wrote:
> > > On Thu, Jan 28, 2016 at 05:01:26PM +0100, Frederic Weisbecker wrote:
> > > > So lets check all the things we call on scheduler_tick():
> > > > 
> > > > _ sched_clock_tick(): maybe it doesn't need to be called when idle. I'm not sure.
> > > >   Some code in idle (timers, irqs, ...) might need to call sched_clock().
> > > 
> > > Only needed if you've got a shady TSC.
> > 
> > Yeh.. IMO, this can be done without the tick handling during nohz, with the
> > patch I am attaching. Could you check the patch? Or we have to handle it
> > remotely, too. (for a crazy TSC)
> 
> I think NOHZ_FULL already requires the TSC not to be wrecked.

What about the regular NOHZ? Or does not any code in idle call a kind of
sched_lock_cpu() at all?

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Re: [PATCH 1/4] sched: Don't account tickless CPU load on tick Frederic Weisbecker <fweisbec@gmail.com> - 2016-01-28 17:10 +0100
  Re: [PATCH 1/4] sched: Don't account tickless CPU load on tick Peter Zijlstra <peterz@infradead.org> - 2016-01-29 11:00 +0100
    Re: [PATCH 1/4] sched: Don't account tickless CPU load on tick Byungchul Park <byungchul.park@lge.com> - 2016-02-01 11:10 +0100
      [PATCH] sched: calculate sched_clock_cpu without tick handling during nohz Byungchul Park <byungchul.park@lge.com> - 2016-02-01 11:20 +0100
      Re: [PATCH 1/4] sched: Don't account tickless CPU load on tick Peter Zijlstra <peterz@infradead.org> - 2016-02-01 11:40 +0100
        Re: [PATCH 1/4] sched: Don't account tickless CPU load on tick Byungchul Park <byungchul.park@lge.com> - 2016-02-02 01:00 +0100
        Re: [PATCH 1/4] sched: Don't account tickless CPU load on tick Byungchul Park <byungchul.park@lge.com> - 2016-02-02 02:00 +0100

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