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

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Date:	Wed, 2 May 2012 15:40:33 -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, Apr 27, 2012 at 09:16:18AM +0900, Namhyung Kim escreveu:
> On Thu, 26 Apr 2012 15:22:55 -0600, David Ahern wrote:
> > On 4/26/12 3:12 PM, Namhyung Kim wrote:
> >> Hmm.. No, I can reproduce it without any of this series. And now I think
> >> that it is not related to the number of cpus. On my 4 core (no
> >> hyperthreading) machine at home, the result was same.
> >>
> >> BTW, did you change sysctl settings?
> >>
> >>    $ cat /sys/devices/system/cpu/online
> >>    0-3
> >>    $ grep . /proc/sys/kernel/perf_event_*
> >>    /proc/sys/kernel/perf_event_max_sample_rate:100000
> >>    /proc/sys/kernel/perf_event_mlock_kb:516
> >>    /proc/sys/kernel/perf_event_paranoid:1
> >
> > $ grep . /proc/sys/kernel/perf_event_*
> > /proc/sys/kernel/perf_event_max_sample_rate:100000
> > /proc/sys/kernel/perf_event_mlock_kb:516
> > /proc/sys/kernel/perf_event_paranoid:-1
> >
> > That last one is the key. I have it set to not paranoid and usually
> > run perf a non-root user.
> >
> 
> That's exactly what I want to see :). On perf_mmap() we have:
> 
> 	if ((locked > lock_limit) && perf_paranoid_tracepoint_raw() &&
> 		!capable(CAP_IPC_LOCK)) {
> 		ret = -EPERM;
> 		goto unlock;
> 	}
> 
> 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
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