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

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Date:   Wed, 5 Jul 2017 15:07:55 +0900
From:   Namhyung Kim <namhyung@...nel.org>
To:     Taeung Song <treeze.taeung@...il.com>
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 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.


>
> 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