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Date: Tue, 21 Jun 2011 20:48:20 +0400
From: Cyrill Gorcunov <gorcunov@gmail.com>
To: Stephane Eranian <eranian@google.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>, Don Zickus <dzickus@redhat.com>,
        Ingo Molnar <mingo@elte.hu>, Lin Ming <ming.m.lin@intel.com>,
        Arnaldo Carvalho de Melo <acme@redhat.com>,
        Frederic Weisbecker <fweisbec@gmail.com>,
        Vince Weaver <vweaver1@eecs.utk.edu>,
        lkml <linux-kernel@vger.kernel.org>
Subject: Re: [RFC -tip] perf, x86: Add PERF_COUNT_HW_NMI_WATCHDOG event v2
Message-ID: <20110621164820.GC21641@sun>
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On Tue, Jun 21, 2011 at 06:20:56PM +0200, Stephane Eranian wrote:
> Cyrill,
> [repost because of MIME crap]

I saw first as well, sorry for delay, my isp is broken today :/

> 
> I admit I don't quite understand how this patch works around
> the limitation. In the end you are still going to program some cycle
> event into a P4 PMU register. So how it is going to free more counters
> for regular users?
> 
> 

  The key here is that we use that named non-sleeping ticks (as oprofile
did) for nmi-watchdog and it allows us to free "cpu-cycles" counter for
user needs. Of course we pick up one counter for this but it doesn't intersect
with "cpu-cycles" counter (because counters are grouped and can count only
specified events in each group). Stepane, should I post more details?

	Cyrill
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