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

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Message-ID: <20160107234746.GB19314@kernel.org>
Date:	Thu, 7 Jan 2016 20:47:46 -0300
From:	Arnaldo Carvalho de Melo <acme@...nel.org>
To:	Namhyung Kim <namhyung@...il.com>
Cc:	Stephane Eranian <eranian@...gle.com>,
	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

Em Fri, Jan 08, 2016 at 07:47:03AM +0900, Namhyung Kim escreveu:
> 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


Oops, Stephane, please try this, so that we can finally merge it :-\

- Arnaldo