Re: [RFC] para virt interface of perf to support kvm guest osstatistics collection in guest os

From: Ingo Molnar
Date: Wed Jun 09 2010 - 06:28:06 EST

* Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:

> On Wed, 2010-06-09 at 12:41 +0300, Avi Kivity wrote:
> >
> > >> Disabling the watchdog is unfortunate. Why is it necessary?
> > >>
> > > perf always uses NMI, so we disable the nmi_watchdog when a perf_event is
> > > set up in case they might have impact.
> > >
> >
> > Ok. Is that the case for the hardware pmus as well? If so it might be
> > done in common code.
> The x86 hardware pmu implementation disables the lapic watchdog too, but
> recent kernels come with a watchdog implementation on top of perf, the old
> lapic one will be depricated.

Note, that code is in -tip, queued for v2.6.36.

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