Subject: Re: Scrolling down broken with "perf top --hierarchy"
To: Namhyung Kim <namhyung@kernel.org>,
        Arnaldo Carvalho de Melo <acme@kernel.org>
References: <20161006163333.GC308@x4> <20161007011753.GA31113@sejong>
 <20161007035118.GA308@x4> <20161007042218.GE31113@sejong>
 <20161007043229.GB308@x4> <20161007045357.GF31113@sejong>
 <20161007143545.GI4809@kernel.org> <20161024051122.GB7720@sejong>
Cc: Markus Trippelsdorf <markus@trippelsdorf.de>,
        linux-kernel@vger.kernel.org, Ingo Molnar <mingo@kernel.org>,
        Peter Zijlstra <a.p.zijlstra@chello.nl>, Jiri Olsa <jolsa@kernel.org>
From: Taeung Song <treeze.taeung@gmail.com>
Message-ID: <1a18335e-6027-1645-5f53-d56c057d780f@gmail.com>
Date: Mon, 24 Oct 2016 19:10:24 +0900
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Hi, Namhyung and Arnaldo :)

On 10/24/2016 02:11 PM, Namhyung Kim wrote:
> 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)?
>

Is related this link with what you said ? 
https://lkml.org/lkml/2016/1/11/495

Yes, the config patchset would be need to be updated.
Because the config patchset which has 'write' feature
don't use a recent 'struct perf_config_set' so I should change it
to use 'perf_config_set' like show_config() of builtin-config.c:36.

Do you need write support of perf-config command ?
If this feature is more necessary than a recent patchset about default 
config array https://lkml.org/lkml/2016/9/5/17,
I'd remake config patchset for getting and setting features first. :)


Thanks,
Taeung