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

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Date:	Fri, 04 May 2012 22:53:29 +0900
From:	Namhyung Kim <namhyung@...il.com>
To:	Arnaldo Carvalho de Melo <acme@...stprotocols.net>
Cc:	Namhyung Kim <namhyung.kim@....com>,
	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

Hi,

On Fri, 4 May 2012 10:37:06 -0300, Arnaldo Carvalho de Melo wrote:
> Em Fri, May 04, 2012 at 01:05:48PM +0900, Namhyung Kim escreveu:
>> 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.
>> >
>> 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?
>

Okay, will do.

Thanks,
Namhyung
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