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

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Date:	Thu, 7 Jan 2016 13:56:14 -0800
From:	Stephane Eranian <eranian@...gle.com>
To:	LKML <linux-kernel@...r.kernel.org>
Cc:	Arnaldo Carvalho de Melo <acme@...nel.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: [RFC] perf record: missing buildid for callstack modules

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.