linux-kernel - Re: [PATCH 2/3] Revert 'perf evlist: Fix creation of cpu map'

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Message-ID: <20120516152619.GD7864@infradead.org>
Date:	Wed, 16 May 2012 12:26:19 -0300
From:	Arnaldo Carvalho de Melo <acme@...stprotocols.net>
To:	Namhyung Kim <namhyung.kim@....com>
Cc:	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Paul Mackerras <paulus@...ba.org>,
	Ingo Molnar <mingo@...hat.com>,
	Namhyung Kim <namhyung@...il.com>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/3] Revert 'perf evlist: Fix creation of cpu map'

Em Wed, May 16, 2012 at 06:45:48PM +0900, Namhyung Kim escreveu:
> The commit 55261f46702c ("perf evlist: Fix creation of cpu
> map") changed to create a per-task event when no cpu target
> is specified. However it caused a problem since perf-task do
> not allow event inheritance due to scalability issues so
> that the result will contain samples only from parent, not
> from its children.
> 
> So we should use perf-task-per-cpu events anyway to get the
> right result. Revert it.
> 
> Reported-by: Linus Torvalds <torvalds@...ux-foundation.org>
> Analysed-by: Ingo Molnar <mingo@...nel.org>
> Acked-and-tested-by: Peter Zijlstra <a.p.zijlstra@...llo.nl>

I'm applying it, but while trying to figure out if the logic was right I
tried:

perf top -C 0 -u acme

To check what is that this user is doing on that CPU, and its not
possible :-\

UID switch overriding CPU!

- Arnaldo
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