linux-kernel - Re: perf-stat per thread results

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Date:	Sat, 14 May 2011 14:49:28 +0200
From:	Wim Heirman <wim@...rman.net>
To:	David Ahern <dsahern@...il.com>
Cc:	Ingo Molnar <mingo@...e.hu>,
	Arnaldo Carvalho de Melo <acme@...hat.com>,
	linux-kernel@...r.kernel.org,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Thomas Gleixner <tglx@...utronix.de>,
	Frédéric Weisbecker <fweisbec@...il.com>,
	Brice Goglin <Brice.Goglin@...ia.fr>
Subject: Re: perf-stat per thread results

On 14 May 2011 01:02, David Ahern <dsahern@...il.com> wrote:
>
>
> On 05/13/11 14:32, Wim Heirman wrote:
>> Hi,
>>
>>> It's supposed to do that if --stat is specified, and it used to work - see this
>>> commit:
>>>
>>>  8d51327090ac: perf report: Fix and improve the displaying of per-thread event counters
>>>
>>> and the output there:
>>>
>>>     #  PID   TID  cache-misses  cache-references
>>>       4658  4659        495581           3238779
>>>       4658  4662        498246           3236823
>>>       4658  4663        499531           3243162
>>>
>>> which appears to be roughly what Wim is asking for, AFAICT.
>>
>> Thanks, this is exactly what I'm looking for. In 2.6.32 (Ubuntu 10.04)
>> it works, although if I use --pid rather than the -- <command> variant
>> the first thread seams to be missing. In 2.6.38 (Ubuntu 11.04) the
>> first thread is missing in both use cases, and I get one column per
>> processor (which in itself is fine).
>>
>> Regards,
>> Wim
>
> Hmm.... my mileage varies using latest kernel
> (446cc6345d3de6571bdd0840f48aca441488a28d)
>
> $ /tmp/build-perf/perf record --stat -fo /tmp/perf.data -p $(pidof rsyslogd)
> ^C[ perf record: Woken up 1 times to write data ]
> [ perf record: Captured and wrote 0.007 MB /tmp/perf.data (~308 samples) ]
>
> $ /tmp/build-perf/perf report -T -i /tmp/perf.data
> # Events: 6  cycles
> #
> # Overhead   Command      Shared Object                      Symbol
> # ........  ........  .................  ..........................
> #
>    97.61%  rsyslogd  libc-2.13.so       [.] __libc_disable_asynccancel
>     2.39%  rsyslogd  [kernel.kallsyms]  [k] native_write_msr_safe
>
>
> #
> # (For a higher level overview, try: perf report --sort comm,dso)
> #
> # PID  TID
>
>
> ie., I do not get the counter values. Specifying the counter with -e
> (e.g., -e branch-misses) does not help -- still no counter output.

Is rsyslogd multithreaded? (Or at least, do the non-main threads
execute any work during your perf-record measurement) If not, then
what you see is consistent with what I'm getting, i.e. everything but
the main thread is reported.

Regards,
Wim
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