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 16:45:08 +0100
From:	Frederic Weisbecker <fweisbec@...il.com>
To:	Ingo Molnar <mingo@...nel.org>
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>,
	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)

On Mon, Nov 11, 2013 at 02:56:37PM +0100, Ingo Molnar wrote:
> 
> * Frederic Weisbecker <fweisbec@...il.com> wrote:
> 
> > On Mon, Nov 11, 2013 at 01:13:52PM +0100, Ingo Molnar wrote:
> > > 
> > > It's not an irrelevant feature at all! :-)
> > > 
> > > It's just that for any sort of longer profile it was pretty 
> > > difficult/frustrating to use, which I think held back adoption.
> > > 
> > > That performance problem got fixed now by you and Namhyung, so I think 
> > > we'll see even wider adoption of call-graph profiling...
> > 
> > Ah I see now. At the time Linus reported his issue, I had the feeling 
> > his usecase was a bit "extreme", but I actually have no idea how far 
> > perf can be used given that I'm mostly used to short benchmarks, 
> > typically hackbench, perf bench sched messaging et al. Thing is I don't 
> > use it enough for my real usecases :)
> 
> Well, it's a bit of a catch-22: if there are severe scalability problems 
> for a usecase then people won't use it because they cannot use it. So 
> developers should usually try to over-measure things and go for extreme 
> uses and such.

Agreed :)
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