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Subject: Re: [RFC PATCH 2/2] perf stat: Use event group to simulate PMI on
 PMI-less hardware counter
From: Peter Zijlstra <peterz@infradead.org>
To: Zhang Rui <rui.zhang@intel.com>
Cc: "Lin, Ming M" <ming.m.lin@intel.com>, Ingo Molnar <mingo@elte.hu>,
        Matt Fleming <matt@console-pimps.org>,
        Frederic Weisbecker <fweisbec@gmail.com>,
        lkml <linux-kernel@vger.kernel.org>,
        Arnaldo Carvalho de Melo <acme@redhat.com>
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Date: Thu, 11 Nov 2010 13:46:41 +0100
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On Thu, 2010-11-11 at 10:00 +0800, Zhang Rui wrote:
> Well, the RAPL package energy perf event may need this piece of code.
> 
>  "MSR_PKG_ENERGY_STATUS is a read-only MSR. It reports the actual energy
> use for the package domain. This MSR is updated every ~1msec. It has a
> wraparound time of around 60 secs when power consumption is high, and
> may be longer otherwise."
> 
> As it's an energy counter, we should show it in "perf stat", right?
> As it doesn't have interrupt, I want to schedule a timer interrupt every
> 30s to update the event counter. 

So use a timer inside the RAPL pmu driver. No need to change the
interface or add generic code.