linux-kernel - Re: [QUESTION] perf annotate: how do we fix the 'total period' feature ?

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Message-ID: <75f62a2d-a9f2-1d08-926b-a1615ef14f45@gmail.com>
Date:   Wed, 5 Jul 2017 15:50:39 +0900
From:   Taeung Song <treeze.taeung@...il.com>
To:     Namhyung Kim <namhyung@...nel.org>
Cc:     Arnaldo Carvalho de Melo <arnaldo.melo@...il.com>,
        LKML <linux-kernel@...r.kernel.org>,
        Jiri Olsa <jolsa@...nel.org>,
        Milian Wolff <milian.wolff@...b.com>
Subject: Re: [QUESTION] perf annotate: how do we fix the 'total period'
 feature ?

Hi Namhyung :)

On 07/05/2017 03:07 PM, Namhyung Kim wrote:
> Hi Taeung,
> 
> On Wed, Jul 5, 2017 at 2:47 PM, Taeung Song <treeze.taeung@...il.com> wrote:
>> Hi,
>>
>> Two problems of perf-annotate were mentioned in recent PATCH reviews
>> by Milian and Namhyung.
>>
>> Currently perf-annotate has a '--show-total-period' option
>> and a 't' key "Toggle total period view" on TUI browser.
> 
> Hmm... I didn't notice it has the option.  I think its name is
> incorrect and should be --show-nr-samples in accordance with perf
> report.
> 
> 

Okey, I got it.

>>
>> However, they actually show the number of samples, not period(Raw number of
>> event count of sample).
>> So it's a different number to the perf report like below.
>>
>> For example,
>>
>>    $ perf report --stdio --show-nr-sample --show-total-period -S hex2u64
>> ...
>> # Overhead       Samples        Period  Command  Shared Object
>> # ........  ............  ............  .......  .............
>> #
>>       3.07%            36      26484668  perf     perf
>>
>>
>>    $ perf annotate  --stdio --show-total-period -s hex2u64
>>   Percent |      Source code & Disassembly of perf for cycles:ppp (36
>> samples)
>> -----------------------------------------------------------------------------
>>           :
>>           :
>>           :
>>           :      Disassembly of section .text:
>>           :
>>           :      000000000053ef9e <hex2u64>:
>>           :      hex2u64():
>>         0 :        53ef9e:       push   %rbp
>>         0 :        53ef9f:       mov    %rsp,%rbp
>>         0 :        53efa2:       sub    $0x30,%rsp
>>         1 :        53efa6:       callq  424810
>> <pthread_attr_setdetachstate@...+0x10>
>>         0 :        53efab:       mov    %rdi,-0x28(%rbp)
>>         2 :        53efaf:       mov    %rsi,-0x30(%rbp)
>> ...
>>
>> Problems:
>>    1) the total period of perf-annotate is different from perf-report's
>>    2) perf-annotate only shows the first column as 'Percent'
>>       (even though the number of samples for each addr are actually printed)
>>
>> So we need to just rename it ? ('total period' -> 'samples')
>>
>> Or,
>> we should enable perf-annotate to support both features for 'periods' and
>> 'samples' ?
> 
> I think we should support both.  Then you need to change the code to
> save periods when processing samples and show them in the annotate
> IMHO.
> 
> Thanks,
> Namhyung
> 

Currently perf-annotate only count the number of samples for each addr
in __symbol__inc_addr_samples() of util/annotate.c when processing samples.
But it seems to make new functions for 'periods'..

Okey, I got hints of how to fix this problems.
will send the PATCH for them ! :)

Thanks,
Taeung