linux-kernel - Re: [PATCH 07/13] perf evlist: Fix creation of cpu map

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Date:	Fri, 4 May 2012 10:37:06 -0300
From:	Arnaldo Carvalho de Melo <acme@...stprotocols.net>
To:	Namhyung Kim <namhyung.kim@....com>
Cc:	David Ahern <dsahern@...il.com>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Paul Mackerras <paulus@...ba.org>,
	Ingo Molnar <mingo@...hat.com>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 07/13] perf evlist: Fix creation of cpu map

Em Fri, May 04, 2012 at 01:05:48PM +0900, Namhyung Kim escreveu:
> Hi,
> 
> On Wed, 2 May 2012 15:40:33 -0300, Arnaldo Carvalho de Melo wrote:
> > Em Fri, Apr 27, 2012 at 09:16:18AM +0900, Namhyung Kim escreveu:
> >> So as long as you set perf_event_paranoid to -1 or run perf test as
> >> root, you cannot see the failure.
> >
> > Ok, as root try 'perf top', here I get, with this patch:
> >
> > [root@...dy ~]# perf top --stdio
> > Warning:
> > The sys_perf_event_open() syscall returned with 22 (Invalid argument).
> > /bin/dmesg may provide additional information.
> > No CONFIG_PERF_EVENTS=y kernel support configured?
> > [root@...dy ~]#
> >
> > Skipping this one, will look again later.
> >
> > - Arnaldo
> 
> Sorry. It is because perf top depends on an undefined behaviour that
> if neither target nor command line argument was specified it'd open
> events for all online cpus. In contrast, perf record and perf stat will
> show the help message in this case.
> 
> This patch makes it clear that we have to prepare a sane target
> configuration before opening a perf event fd. So I think we should fix
> perf top to set top.target.system_wide to true by default.

So please provide a preparatory patch for top before this one, ok?

- Arnaldo
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