linux-kernel - Re: [RFC/PATCHSET 00/14] perf report: Add support to accumulate hist periods (v2)

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Date:	Mon, 11 Nov 2013 13:19:00 +0100
From:	Ingo Molnar <mingo@...nel.org>
To:	David Ahern <dsahern@...il.com>
Cc:	Namhyung Kim <namhyung@...nel.org>,
	Pekka Enberg <penberg@...nel.org>,
	Arnaldo Carvalho de Melo <acme@...stprotocols.net>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Paul Mackerras <paulus@...ba.org>,
	Namhyung Kim <namhyung.kim@....com>,
	LKML <linux-kernel@...r.kernel.org>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Stephane Eranian <eranian@...gle.com>,
	Jiri Olsa <jolsa@...hat.com>,
	Rodrigo Campos <rodrigo@...g.com.ar>,
	Arun Sharma <asharma@...com>
Subject: Re: [RFC/PATCHSET 00/14] perf report: Add support to accumulate hist
 periods (v2)


* David Ahern <dsahern@...il.com> wrote:

> On 11/6/13, 4:47 AM, Ingo Molnar wrote:
> >I'm not too worried about call-graph 'legacies': it generates such huge
> >perf.data files which is parsed so slowly at the moment that there's very
> >little user base ... Anyone who absolutely needs call-graph profiling uses
> >SysProf which performs well.
> 
> Actually, perf with callchains is used quite heavily on my products.
> One of the selling points of perf.

That's nice to hear :)

In what way is call-graph profiling utilized typically?

Is it system-wide, i.e. something like:

	perf record -a -g sleep 10

? If yes then that would explain why scalability problems rarely surfaced, 
it takes a longer user-space profile to get to the event counts where 
scalability started hurting.

Thanks,

	Ingo
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