Re: [PATCH V3]hrtimer: Fix a performance regression by disablereprogramming in remove_hrtimer
From: Peter Zijlstra
Date: Tue Jul 30 2013 - 05:35:32 EST
On Tue, Jul 30, 2013 at 05:12:49PM +0800, Ethan Zhao wrote:
> On Mon, Jul 29, 2013 at 6:18 PM, Thomas Gleixner <tglx@xxxxxxxxxxxxx> wrote:
> > The test case does not involve anything hrtimer related. Do you have
> > CONFIG_SCHED_HRTICK enabled?
> Yes. it is default configured in stable release.
Should still be disabled by default even if supported:
# grep HRTICK kernel/sched/features.h
> > First of all we want to know, which particular hrtimer is causing that
> > issue. If it is the hrtick one, then I really have to ask why you want
> > to use it at all in such a high performance scenario.
> > Any advice about the HZ in high performance scenario ? hrtimer tick
> Is not fit for high performance ?
Hence why its disabled, programming the timer hardware is too expensive.
But since you didn't even know that I suspect you aren't in fact using
It would be good if you could do what Thomas suggested and look at which
timer is actually active during your workload.
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