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

Ingo Molnar
2009-06-24T17:47:52Z

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

> On Mon, 22 Jun 2009 17:40:30 +0200
> Ingo Molnar <mingo@elte.hu> wrote:
>
> >
> > * Martin Schwidefsky <schwidefsky@de.ibm.com> wrote:
> >
> > > On Mon, 22 Jun 2009 17:29:37 +0200
> > > Ingo Molnar <mingo@elte.hu> wrote:
> > >
> > > >
> > > > * Martin Schwidefsky <schwidefsky@de.ibm.com> wrote:
> > > >
> > > > > [...] And if we really want to keep things separate there will be
> > > > > two sets of per-cpu hrtimer, one for the old style profiler and
> > > > > one for oprofile. Any preference for the user space interface to
> > > > > set the sample rate? A sysctl?
> > > >
> > > > I dont think we want to keep things separate. Regarding old-style
> > > > profiler, does anyone still use it? There's now a superior in-tree
> > > > replacement for it, so we could phase it out.
> > >
> > > Well, for my part I won't miss it. But to be able to remove the
> > > profile_tick() calls from the architectures I either have to rip
> > > out the old profiler now, or adapt it to use hrtimer as well.
> >
> > Do we _have to_ touch it so widely right now? We could start with a
> > deprecation warning in this cycle. Once it's deprecated we can
> > remove all those calls.
>
> First version of the hrtimer patch for oprofile. I did not add the
> sysctl yet, if the sysctl is added in oprofile_timer_init it would
> not be available if some better profiling source is available. If
> it is added unconditionally it would only have an effect if the
> timer fallback is used. Both cases are not exactly nice for a user
> space interface.

looks quite sane. I've Cc:-ed Robert.

Ingo