linux-kernel - Re: [PATCH 1/3] perf callchain: Convert children list to rbtree

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Date:	Tue, 10 Sep 2013 12:25:54 +0200
From:	Ingo Molnar <mingo@...nel.org>
To:	Jiri Olsa <jolsa@...hat.com>,
	Frédéric Weisbecker <fweisbec@...il.com>
Cc:	Namhyung Kim <namhyung@...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>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Frederic Weisbecker <fweisbec@...il.com>
Subject: Re: [PATCH 1/3] perf callchain: Convert children list to rbtree


* Jiri Olsa <jolsa@...hat.com> wrote:

> On Tue, Sep 10, 2013 at 05:24:16PM +0900, Namhyung Kim wrote:
> > From: Namhyung Kim <namhyung.kim@....com>
> > 
> > Current collapse stage has a scalability problem which can be
> > reproduced easily with parallel kernel build.  This is because it
> > needs to traverse every children of callchain linearly during the
> > collapse/merge stage.  Convert it to rbtree reduced the overhead
> > significantly.
> > 
> > On my 400MB perf.data file which recorded with make -j32 kernel build:
> 
> 
> nice!!!

Nice indeed!

> tried on 2.6 GB data file from kernel make -j64 and got report speed up 
> from 'never' to 2m52.756s ;-)

It's still rather long though, unacceptable for everyday usage :-/

Frederic thought that we could reduce minimize collapsing to begin with.

Frederic, could you outline that in more detail please?

Thanks,

	Ingo
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