linux-kernel - Re: Scrolling down broken with "perf top --hierarchy"

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Date:   Mon, 24 Oct 2016 14:11:22 +0900
From:   Namhyung Kim <namhyung@...nel.org>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>
CC:     Markus Trippelsdorf <markus@...ppelsdorf.de>,
        <linux-kernel@...r.kernel.org>, Ingo Molnar <mingo@...nel.org>,
        Peter Zijlstra <a.p.zijlstra@...llo.nl>,
        Jiri Olsa <jolsa@...nel.org>,
        Taeung Song <treeze.taeung@...il.com>
Subject: Re: Scrolling down broken with "perf top --hierarchy"

Hi Arnaldo,

Sorry for late reply.

On Fri, Oct 07, 2016 at 11:35:45AM -0300, Arnaldo Carvalho de Melo wrote:
> Em Fri, Oct 07, 2016 at 01:53:57PM +0900, Namhyung Kim escreveu:
> > Cc-ing perf maintainers,
> > 
> > On Fri, Oct 07, 2016 at 06:32:29AM +0200, Markus Trippelsdorf wrote:
> > > On 2016.10.07 at 13:22 +0900, Namhyung Kim wrote:
> > > > On Fri, Oct 07, 2016 at 05:51:18AM +0200, Markus Trippelsdorf wrote:
> > > > > On 2016.10.07 at 10:17 +0900, Namhyung Kim wrote:
> > > > > > On Thu, Oct 06, 2016 at 06:33:33PM +0200, Markus Trippelsdorf wrote:
> > > > > > > Scrolling down is broken when using "perf top --hierarchy".
> > > > > > > When it starts up everything is OK and one can scroll up and down to all
> > > > > > > entries. But as further and further new entries get added to the list,
> > > > > > > scrolling down is blocked (at the position of the last entry that was
> > > > > > > shown directly after startup).
> > > > > > 
> > > > > > I think below patch will fix the problem.  Please check.
> > > > > 
> > > > > Yes. It works fine now. Many thanks.
> > > > 
> > > > Good.  Can I add your Tested-by then?
> > > 
> > > Sure.
> > 
> > Ok, I'll send a formal patch with it.
> > 
> > > 
> > > (And in the long run you should think of making "perf top --hierarchy"
> > > the default for perf top, because it gives a much better (uncluttered)
> > > overview of what is going on.)
> > 
> > I think it's a matter of taste.  Some people prefer to see the top
> > single function or something (i.e. current behavior) while others
> > prefer to see a higher-level view.
> > 
> > But we can think again about the default at least for perf-top.  I
> > worried about changing default behavior because last time we did it
> > for children mode many people complained about it.  But I do think the
> > hierarchy mode is useful for many people though.
> 
> So, I think in such cases we could experiment with asking the user about
> switching to the new mode by showing a popup message telling what it is
> about, if the user says "yes, I want to try it" switch to it and if
> another hotkey is pressed later, write what was chosen (yes, switch to
> this new mode, no, I don't like it, don't pester me about it anymore) to
> its ~/.perfconfig file so that next time it goes straight to this new
> mode, else don't ask the user again and keep using whatever mode was
> there already.
> 
> What do you think?

I think it's a flexible way to set the default behavior while it seems
like a little bit complicated for implementation.  Also I think it's
better to popup another dialog at the end and asks for comfirmation
(but it might not be appropriate for --stdio).

And to do that, we need to have a (programmable) way of dealing with
the configs.

Taeung, is there an update on your config patchset (especially for
write support)?

Thanks,
Namhyung