Re: [patch 0/2] NOHZ vs. profile/oprofile v2

From: Ingo Molnar
Date: Mon Jun 22 2009 - 11:06:19 EST



* Martin Schwidefsky <schwidefsky@xxxxxxxxxx> wrote:

> On Mon, 22 Jun 2009 16:41:10 +0200
> Ingo Molnar <mingo@xxxxxxx> wrote:
>
> > Hm, this is rather ugly. Why not use hrtimers like 'perf' does when
> > it fallback-samples based on the timer tick?
> >
> > That method has three advantages:
> >
> > - no weird hookery needed
> > - resolution can go far beyond HZ
> > - it is evidently dynticks-safe
>
> Hmm, if we replace the HZ based oprofile tick with an hrtimer we
> should add an interface to configure the sample interval as well,
> no? Otherwise we just replace one timer event (HZ) with another
> (hrtimer).

Even if the hrtimer is set with a 1/HZ period it's a better
solution, as it's dynticks safe without invasive changes.

Ingo
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