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

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Date:	Mon, 19 Oct 2015 17:16:53 -0700
From:	Brendan Gregg <brendan.d.gregg@...il.com>
To:	Arnaldo Carvalho de Melo <arnaldo.melo@...il.com>
Cc:	Ingo Molnar <mingo@...nel.org>,
	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 Fri, Oct 9, 2015 at 3:25 PM, Arnaldo Carvalho de Melo
<arnaldo.melo@...il.com> wrote:
> Em Fri, Oct 09, 2015 at 03:10:29PM -0700, Brendan Gregg escreveu:
>> On Fri, Oct 9, 2015 at 2:56 PM, Arnaldo Carvalho de Melo
>> <arnaldo.melo@...il.com> wrote:
>> >
>> > Em Fri, Oct 09, 2015 at 01:34:33PM -0700, Brendan Gregg escreveu:
>> > > On Mon, Oct 5, 2015 at 2:03 PM, Arnaldo Carvalho de Melo
>> > > <acme@...nel.org> wrote:
>> > > >
>> > > > From: Arnaldo Carvalho de Melo <acme@...hat.com>
>> > > >
>> > > > Which is the most common default found in other similar tools.
>> > >
>> > > Interactive tools, sure, like the perf report TUI.
>> >
>> > > But this also changes the ordering of the non-interactive tools which
>> > > dump stacks: "perf report -n --stdio" and "perf script". The most
>> > > common default for dumping stacks is caller. Eg:
>> >
>> > And you use that for scripting?
>>
>> Yes; how I typically CPU profile:
>>
>> git clone https://github.com/brendangregg/FlameGraph
>> cd FlameGraph
>> perf record -F 99 -a -g -- sleep 60
>> perf script | ./stackcollapse-perf.pl | /flamegraph.pl > flame.svg
>>
>> Then open flame.svg in a browser and click around. Try it. :)
>
> Should've already, guess there are things to merge and save you some
> time :)
>
>> But it's not just scripting; We often email around "perf report -n
>> --stdio" output, or attach it to tickets, when working on an issue.
>> Easier than trying to grab the right TUI screenshot.
>
> Well, that is something we need to change... But then, are you aware of
> 'P' in the TUI? It allows you to go, expand whatever callchains you deem
> necessary and then press P and the current state of the UI will be
> dumped to a perf.hist.<N> file. I.e. no need to get a png screenshot nor
> to copy things with gpm like stuff.
> [...]

I didn't know about 'P', thanks. I still find it quicker to "perf
report -n --stdio", then browse with my eyes and the scroll wheel.
(Then use a flame graph if the output isn't trivial to understand.)

... Just to express a callee order preference differently (at least
for the text dumping outputs), it's showing what's running (first few
frames) followed by how we got there. And that's the order I'm usually
wanting to know them... I still think it's the order printed by most
other text-based tools, although GUIs (like those with tree views) are
probably more usually caller order.

Brendan
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