linux-kernel - Re: callchain sampling bug in perf?

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Date:	Fri, 20 Aug 2010 05:16:45 -0400
From:	Christoph Hellwig <hch@...radead.org>
To:	Arnaldo Carvalho de Melo <acme@...radead.org>
Cc:	Christoph Hellwig <hch@...radead.org>,
	Frederic Weisbecker <fweisbec@...il.com>,
	linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...e.hu>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>
Subject: Re: callchain sampling bug in perf?

On Thu, Aug 19, 2010 at 12:04:22PM -0300, Arnaldo Carvalho de Melo wrote:
> 
> [acme@...pio tmp]$ perf report
> 
> http://vger.kernel.org/~acme/perf/perf-report-tui-callchain-xlog_sync.png
> 
> So it seems to work (you tell me if the callchains make sense), and the problem

I've rebuilt perf with libnewt to reproduce it, but to get any of the
callchain data I need to call perf report with a -g argument (which is
rather expected from the documentation anyway)

I still see the same problems as with the TUI perf report with that.
With the -g {mode},0.0 there is nothing to expand inside the GUI for
e.g. the pythong process, and with the 0.0 threshold I can only expand
a few 0.<something> callchains, but I never see the 80% your screenshot
shows.  What perf version are you running?

Also the flat mode is rendered incorrectly, it just adds different call
graphs inside a single process directly after each other instead of
separating them in the rendering.

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