linux-kernel - Re: [PATCHSET 0/8] perf tools: Fix scalability problem on callchain merging (v5)

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Date:	Fri, 11 Oct 2013 07:58:29 +0200
From:	Ingo Molnar <mingo@...nel.org>
To:	Namhyung Kim <namhyung@...nel.org>
Cc:	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>,
	Jiri Olsa <jolsa@...hat.com>
Subject: Re: [PATCHSET 0/8] perf tools: Fix scalability problem on callchain
 merging (v5)


* Namhyung Kim <namhyung@...nel.org> wrote:

> Hello,
> 
> This is a new version of callchain improvement patchset.  Basically
> it's almost same as v4 but rebased on current acme/perf/core and some
> functions are renamed as Frederic requested.
> 
> Now I'm hunting down a bug in 'perf report -s sym' which was found
> during the test, but I think it's not related to this change as it can
> be reproduced in earlier versions too.
> 
> I put this series on 'perf/callchain-v5' branch in my tree
> 
>   git://git.kernel.org/pub/scm/linux/kernel/git/namhyung/linux-perf.git
> 
> Any comments are welcome, thanks.

One thing I noticed about call-graph profiling:

  comet:~/tip/tools/perf> ./perf record -g ~/hackbench 10
  callchain: Unknown -g option value: /home/mingo/hackbench

I think a naked -g used to work just fine in the past. Even if such an 
error is displayed the output is very unhelpful, it does does a full 
perf-record options dump (unnecessary), the bit that is helpful is hidden 
amongst many other options:

    -g, --call-graph <mode[,dump_size]>
                          do call-graph (stack chain/backtrace) recording: [fp] dwarf

and it took me two reads to see that I should specify 'fp'. The '[fp]' 
indicates that fp is the default - but that does not appear to be working.

Another thing I noticed is that there are a fair number of conflicts 
against perf/core, and some more against Arnaldo's tree.

Otherwise it seems to be working well!

Thanks,

	Ingo

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