linux-kernel - Re: [RFC/PATCHSET 00/17] perf tools: Add support for hierachy view (v2)

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Message-ID: <20160120013612.GE18796@sejong>
Date:	Wed, 20 Jan 2016 10:36:12 +0900
From:	Namhyung Kim <namhyung@...nel.org>
To:	Andi Kleen <andi@...stfloor.org>
CC:	Arnaldo Carvalho de Melo <acme@...nel.org>,
	Ingo Molnar <mingo@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Jiri Olsa <jolsa@...nel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	David Ahern <dsahern@...il.com>,
	Stephane Eranian <eranian@...gle.com>,
	Wang Nan <wangnan0@...wei.com>,
	Don Zickus <dzickus@...hat.com>,
	Pekka Enberg <penberg@...nel.org>,
	Moinuddin Quadri <moin18@...il.com>
Subject: Re: [RFC/PATCHSET 00/17] perf tools: Add support for hierachy view
 (v2)

Hi Andi,

On Wed, Jan 20, 2016 at 02:11:00AM +0100, Andi Kleen wrote:
> On Wed, Jan 20, 2016 at 09:56:47AM +0900, Namhyung Kim wrote:
> > On Tue, Jan 19, 2016 at 07:24:49PM -0300, Arnaldo Carvalho de Melo wrote:
> > > Em Tue, Jan 19, 2016 at 11:12:04PM +0100, Andi Kleen escreveu:
> > > > It only considers the hits on the leaf function, but doesn't hide
> > > > the individual call chains leading to that function which are below
> > > > the limit.
> > > > 
> > > > So if you have a lot of different cold callers you still end up
> > > > with far too much output.
> > 
> > Could you please be more specific?  Let me try with an example..
> > 
> >   $ perf report
> >   ...
> >   +    1.00%  perf  perf  some_function
> >            some_function
> >          - common_caller
> >             - 0.6% caller1
> >               + 0.4% caller1_1
> >               + 0.2% caller1_2
> >             + 0.3% caller2
> >             + 0.1% caller3
> > 
> > In this case, do you want this?
> > 
> >   $ perf report --percent-limit 0.5
> >   ...
> >   +    1.00%  perf  perf  some_function
> >            some_function
> >          - common_caller
> >             - 0.6% caller1
> 
> Right. Only call chains whose total percentage is larger than the limit.

So in this case, caller1_1 and caller1_2 are both under the percent
limit but after they merged at caller1, it should be shown.  Look like
a reasonable result.  I'll add it into my TODO list. :)

Btw, is it all you wanted to say?  Is there any other case for trouble
(wrt callchain percent limit)?

Thanks,
Namhyung