linux-kernel - Re: [PATCH 13/16] perf callchain: Switch default to 'graph,0.5,caller'

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Date:	Wed, 21 Oct 2015 12:18:10 -0700
From:	Brendan Gregg <brendan.d.gregg@...il.com>
To:	Ingo Molnar <mingo@...nel.org>
Cc:	Arnaldo Carvalho de Melo <arnaldo.melo@...il.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Adrian Hunter <adrian.hunter@...el.com>,
	Borislav Petkov <bp@...e.de>,
	Chandler Carruth <chandlerc@...il.com>,
	David Ahern <dsahern@...il.com>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Jiri Olsa <jolsa@...hat.com>,
	Namhyung Kim <namhyung@...nel.org>,
	Stephane Eranian <eranian@...gle.com>,
	Wang Nan <wangnan0@...wei.com>
Subject: Re: [PATCH 13/16] perf callchain: Switch default to 'graph,0.5,caller'

On Wed, Oct 21, 2015 at 1:06 AM, Ingo Molnar <mingo@...nel.org> wrote:
>
> * Arnaldo Carvalho de Melo <arnaldo.melo@...il.com> wrote:
>
>> Indeed, finding a default that is deemed adequate for most people is, ho-hum,
>> difficult 8-)
>>
>> Ingo, what do you think?
>
> So I think the new default is a lot more intuitive, because it starts with a high
> level top-down 'overview' kind of output, allowing one to drill down to the
> details.
>

Yes, it may be more intuitive.

> That's what most other tools do as well by default, and people migrating to perf
> found it pretty confusing that we do a bottom-up kind of callgraph.
> [...]

But I don't think it's commonplace. Which other tools do this? Java
Flight Recorder? GUIs? Certainly not text-based system profilers or
debuggers (I made a list in another email).

Although, these are usually printing entire stacks. So the most alien
change would be to flip the "perf script" order (please don't do
this). You could argue that the perf report/top tree view is not
commonplace from other text-based profilers or debuggers, so changing
it won't be as confusing. In fact, it's like a sideways flame graph
(except it doesn't fit on the screen!).

Brendan
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