Re: [RFC -tip] perf, x86: Add PERF_COUNT_HW_NMI_WATCHDOG event v2

From: Peter Zijlstra
Date: Tue Jun 21 2011 - 12:00:58 EST

On Tue, 2011-06-21 at 19:40 +0400, Cyrill Gorcunov wrote:
> On Tue, Jun 21, 2011 at 7:23 PM, Don Zickus <dzickus@xxxxxxxxxx> wrote:
> > On Thu, Apr 28, 2011 at 07:37:25PM +0400, Cyrill Gorcunov wrote:
> >> Due to restriction and specifics of Netburst PMU we need a separated
> >> event for NMI watchdog. In particular every Netburst event consume not
> >> just a counter and config register, but also an additional ESCR register.
> >> Since ESCR registers are grouped upon counters (i.e. if ESCR is occupied
> >> for some event there is no room for another event to enter the room until
> >> it's released) we need to pick up "least" used ESCR (or most available)
> >> for nmi-watchdog purpose -- MSR_P4_CRU_ESCR2/3 was chosen.
> >>
> >> Note that on all other PMUs which support relocation of events between
> >> counters this event is a simple alias for PERF_COUNT_HW_CPU_CYCLES.
> >
> > Cyril,
> >
> > What ever happened with this patch?
> >
> > Cheers,
> > Don
> >
> Well, it's flowing around, I didn't get any more Ack's other than your. Since it
> introduces kind of abi I presume more ack's would be welcome before it
> (possibly) get merged.

we could avoid that abi thing by simply not making it an exposed event

Its not like userspace ever should be using it anyway
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