linux-kernel - Re: [RFC -tip] perf, x86: Add PERF_COUNT_HW_NMI

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Date:	Tue, 21 Jun 2011 17:58:53 +0200
From:	Peter Zijlstra <a.p.zijlstra@...llo.nl>
To:	Cyrill Gorcunov <gorcunov@...nvz.org>
Cc:	Don Zickus <dzickus@...hat.com>, Ingo Molnar <mingo@...e.hu>,
	Lin Ming <ming.m.lin@...el.com>,
	Arnaldo Carvalho de Melo <acme@...hat.com>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Stephane Eranian <eranian@...gle.com>,
	Vince Weaver <vweaver1@...s.utk.edu>,
	lkml <linux-kernel@...r.kernel.org>
Subject: Re: [RFC -tip] perf, x86: Add PERF_COUNT_HW_NMI_WATCHDOG event v2

On Tue, 2011-06-21 at 19:40 +0400, Cyrill Gorcunov wrote:
> On Tue, Jun 21, 2011 at 7:23 PM, Don Zickus <dzickus@...hat.com> 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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