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

Ingo Molnar
2009-06-22T15:06:15Z

* Martin Schwidefsky <schwidefsky@de.ibm.com> wrote:

> On Mon, 22 Jun 2009 16:41:10 +0200
> Ingo Molnar <mingo@elte.hu> 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