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From: Francis Moreau <francis.moro@gmail.com>
To: Victor Jimenez <victor.javier@bsc.es>
Cc: Reid Kleckner <reid.kleckner@gmail.com>,
        Frederic Weisbecker <fweisbec@gmail.com>, linux-kernel@vger.kernel.org,
        Ingo Molnar <mingo@elte.hu>, Peter Zijlstra <a.p.zijlstra@chello.nl>,
        Arnaldo Carvalho de Melo <acme@redhat.com>,
        Stephane Eranian <eranian@google.com>,
        linux-perf-users@vger.kernel.org
Subject: Re: perf tools miscellaneous questions
References: <fa.SSgtQesEhEQa5DUYUwBV3fWtoV4@ifi.uio.no>
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	<fa.MOg61Pcfdp2SJnwM2GFdOxP+xt0@ifi.uio.no>
	<fa.4sHfhlc/fMhpYgKda4IfUHZ7jMY@ifi.uio.no>
Date: Fri, 05 Nov 2010 13:38:12 +0100
In-Reply-To: <fa.4sHfhlc/fMhpYgKda4IfUHZ7jMY@ifi.uio.no> (Victor Jimenez's
	message of "Thu, 04 Nov 2010 22:36:15 UTC")
Message-ID: <m2wros3pzf.fsf@gmail.com>
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Victor Jimenez <victor.javier@bsc.es> writes:

[...]

> If you are measuring last level cache misses, I would recommend you to
> use a memory intensive application/benchmark instead of /bin/true, as
> otherwise there can be a significant variation between two runs.

I agree.

But still with intensive application, I got the same results:


  $ perf stat -r3 -e cache-misses:u gzip -9 -c vmlinux.o >/dev/null

   Performance counter stats for 'gzip -9 -c vmlinux.o' (3 runs):

               950704  cache-misses               ( +-  24.925% )

         82.619412905  seconds time elapsed   ( +-   0.072% )


  $ perf stat -r3 -e llc-load-misses:u,llc-store-misses:u gzip -9 -c vmlinux.o >/dev/null

   Performance counter stats for 'gzip -9 -c vmlinux.o' (3 runs):
  
               317054  LLC-load-misses            ( +-  11.758% )
               162634  LLC-store-misses           ( +-   9.700% )

         82.657099783  seconds time elapsed   ( +-   0.167% )

Thanks
-- 
Francis
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