linux-kernel - Re: [PATCH 2/2] perf callchain: Use global caching provided by libunwind

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Message-ID: <87lhp3i27d.fsf@sejong.aot.lge.com>
Date:	Mon, 29 Sep 2014 11:35:02 +0900
From:	Namhyung Kim <namhyung@...nel.org>
To:	Jean Pihet <jean.pihet@...aro.org>
Cc:	Arun Sharma <asharma@...com>,
	Arnaldo Carvalho de Melo <acme@...nel.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Ingo Molnar <mingo@...nel.org>,
	Paul Mackerras <paulus@...ba.org>,
	Namhyung Kim <namhyung.kim@....com>,
	LKML <linux-kernel@...r.kernel.org>, Jiri Olsa <jolsa@...hat.com>
Subject: Re: [PATCH 2/2] perf callchain: Use global caching provided by libunwind

Hi Jean,

On Fri, 26 Sep 2014 09:14:41 +0200, Jean Pihet wrote:
> Hi,
>
> On 26 September 2014 07:50, Namhyung Kim <namhyung@...nel.org> wrote:
>> Hi Jean,
>>
>> On Wed, 24 Sep 2014 15:45:57 +0200, Jean Pihet wrote:
>>> Hi!
>>>
>>> Here are the test results on ARMv7 for the 2 patches. The speedup is
>>> about x2.1 for identical unwinding output data.
>>>
>>> 'perf record --call-graph dwarf -- stress --cpu 2 --io 2 --vm 2
>>> --timeout 10s' generates a 365 MB perf.data file.
>>>
>>> time perf.orig report --sort symbol --call-graph --stdio 2&>1 > /dev/null
>>> average on 3 runs
>>> real    36.736
>>> user   14.79
>>> sys    21.91
>>>
>>> time perf.libunwind.speedup report --sort symbol --call-graph --stdio
>>> 2&>1 > /dev/null
>>> average on 3 runs
>>> real    17.41        x2.11
>>> user     6.42        x2.3
>>> sys    10.97        x2
>>>
>>> So the patches definitely speedup the unwinding.
>>> FWIW: Acked-by: Jean Pihet <jean.pihet@...aro.org>
>>
>> Thanks for your test!
>>
>> Btw, have you checked the difference of the output before and after the
>> caching?
> Yes the output is identical (as stated here above).

Ah, I misunderstood it.  Thanks for your confirmation. :)

Thanks,
Namhyung
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