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

From: Peter Zijlstra
Date: Wed Jun 09 2010 - 06:08:56 EST

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.

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