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Date: Thu, 26 Apr 2012 15:22:55 -0600
From: David Ahern <dsahern@gmail.com>
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To: Namhyung Kim <namhyung@gmail.com>
CC: Namhyung Kim <namhyung.kim@lge.com>,
        Arnaldo Carvalho de Melo <acme@ghostprotocols.net>,
        Peter Zijlstra <a.p.zijlstra@chello.nl>,
        Paul Mackerras <paulus@samba.org>, Ingo Molnar <mingo@redhat.com>,
        LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 07/13] perf evlist: Fix creation of cpu map
References: <1335417327-11796-1-git-send-email-namhyung.kim@lge.com>  <1335417327-11796-8-git-send-email-namhyung.kim@lge.com>  <4F996433.7040003@gmail.com> <1335474778.1497.14.camel@leonhard>
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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.

>    $ ./perf test 7
>     7: Validate PERF_RECORD_* events&  perf_sample fields: FAILED!
>    $ ./perf --version
>    perf version 3.4.rc1

running 3.4-rc4 kernel + perf from tip/perf/core branch.

David