linux-kernel - Re: [RFC/PATCHSET 00/18] perf report: Add support to accumulate hist periods (v3)

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Date:	Wed, 18 Dec 2013 23:37:49 +0900
From:	Namhyung Kim <namhyung@...nel.org>
To:	Ingo Molnar <mingo@...nel.org>
Cc:	Arnaldo Carvalho de Melo <acme@...stprotocols.net>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Paul Mackerras <paulus@...ba.org>,
	Namhyung Kim <namhyung.kim@....com>,
	LKML <linux-kernel@...r.kernel.org>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Arun Sharma <asharma@...com>, Jiri Olsa <jolsa@...hat.com>,
	Rodrigo Campos <rodrigo@...g.com.ar>
Subject: Re: [RFC/PATCHSET 00/18] perf report: Add support to accumulate
 hist periods (v3)

2013-12-18 (수), 10:46 +0100, Ingo Molnar:
> * Namhyung Kim <namhyung@...nel.org> wrote:
> 
> > I changed the option as a separate --cumulate and added a new 
> > "Total" column (and renamed the default "Overhead" column into 
> > "Self").  The output will be sorted by total (cumulative) overhead 
> > for now.  The reason I changed to the --cumulate is that I still 
> > think it's much different from other --callchain options and I plan 
> > to add support for showing (remaining) callchains to cumulative 
> > entries too.  The --callchain option will take care of it even with 
> > --cumulate option.
> 
> So I still think this is a fantastic feature, and while this variant 
> of the user interface is an improvement over the previous version, we 
> are not there yet ;-)

Right.  But I want to finish the core part of this patchset first.  And
then I will work on the UI part since it'll be a quite large work by
itself, I guess.

> 
> My main complaint that any variation of 'cumulative' or 'cumulate' is 
> a tongue-twister to users. I certainly won't be able to remember it 
> and will have to call up the manpage every time I use it - which will 
> be very annoying. I'd probably not use the feature much.
> 
> So lets approach this from the casual user's angle. Casual users don't 
> really remember twisted names for command line options, they remember 
> the big picture, big concepts, and they remember bits of the output:
> 
> > When the -g cumulative option is given, it'll be shown like this:
> > 
> >   $ perf report --cumulate --stdio
> > 
> >   #     Self     Total  Command      Shared Object                   Symbol
> >   # ........  ........  .......  .................  .......................
> >   #
> >        0.00%    88.29%      abc  libc-2.17.so       [.] __libc_start_main  
> >        0.00%    88.29%      abc  abc                [.] main               
> >        0.00%    88.29%      abc  abc                [.] c                  
> >        0.00%    88.29%      abc  abc                [.] b                  
> >       88.29%    88.29%      abc  abc                [.] a                  
> >        0.00%    11.61%      abc  ld-2.17.so         [.] _dl_sysdep_start   
> 
> So the natural way to get this would something like:
> 
> 	perf report --total
> 
> Or, if '--total' does not feel good, maybe we should change 'Total' to 
> 'Siblings' or 'Children', and propagate that naming through the UI:

Childrend looks better to me.

> 
>    $ perf report --children --stdio
>  
>    #     Self  Children  Command      Shared Object                   Symbol
>    # ........  ........  .......  .................  .......................
>    #
>         0.00%    88.29%      abc  libc-2.17.so       [.] __libc_start_main  
>         0.00%    88.29%      abc  abc                [.] main               
>         0.00%    88.29%      abc  abc                [.] c                  
>         0.00%    88.29%      abc  abc                [.] b                  
>        88.29%    88.29%      abc  abc                [.] a                  
>         0.00%    11.61%      abc  ld-2.17.so         [.] _dl_sysdep_start   
> 
> Which shows the sum of overhead of all child functions as well, not 
> just ourselves.
> 
> Anything but 'cumulative'. That word, beyond being a strange, hard to 
> remember Latin word, also does not tell the user (or the developer) 
> anything about _what_ is being accumulated. It could cover anything.
> 
> I also think this option should be enabled by default - lets see how 
> much people complain about that.
> 
> Okay?

Okay.  I'll make it default in the next spin.

Thanks,
Namhyung


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