linux-kernel - Re: [RFC] perf record: missing buildid for callstack modules

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Date:	Fri, 08 Jan 2016 07:47:03 +0900
From:	Namhyung Kim <namhyung@...il.com>
To:	Stephane Eranian <eranian@...gle.com>,
	Arnaldo Carvalho de Melo <acme@...nel.org>
CC:	LKML <linux-kernel@...r.kernel.org>, Jiri Olsa <jolsa@...nel.org>,
	Namhyung Kim <namhyung@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...nel.org>,
	Adrian Hunter <adrian.hunter@...el.com>,
	"ak@...ux.intel.com" <ak@...ux.intel.com>
Subject: Re: [RFC] perf record: missing buildid for callstack modules

On January 8, 2016 7:00:35 AM GMT+09:00, Stephane Eranian <eranian@...gle.com> wrote:
>On Thu, Jan 7, 2016 at 1:59 PM, Arnaldo Carvalho de Melo
><acme@...nel.org> wrote:
>> Em Thu, Jan 07, 2016 at 01:56:14PM -0800, Stephane Eranian escreveu:
>>> Hi,
>>>
>>> Whenever you do:
>>>
>>>     $ perf record -g -a sleep 10
>>>
>>> Perf will collect the callstack for each sample. At the end of the
>>> run, perf record
>>> adds the buildid for all dso with at least one sample. But when it
>does this, it
>>> only looks at the sampled IP and ignore the modules traversed by the
>callstack.
>>> That means that, it is not possible to uniquely identify the modules
>executed,
>>> unless they had at least one IP sample captured. But this is not
>>> always the case.
>>>
>>> How about providing an option to perf record to force collecting
>>> buildid for all IPs
>>> captured in the callstack? I understand that would cost more at the
>end of the
>>> collection, but this would be beneficial to several monitoring
>scenarios.
>>
>> I agree, would consider applying a patch that provides the option but
>> does not do this by default.
>>
>I agree, not the default.

Hi Stephane,

Please see

https://lkml.org/lkml/2015/3/22/249

Thanks,
Namhyung

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