linux-kernel - Re: FW: [RFC 0/5] perf tools: Add perf data CTF conversion

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Message-ID: <5460156E.3050601@voxpopuli.im>
Date:	Sun, 09 Nov 2014 20:31:26 -0500
From:	Alexandre Montplaisir <alexmonthy@...populi.im>
To:	Sebastian Andrzej Siewior <bigeasy@...utronix.de>
CC:	Jiri Olsa <jolsa@...hat.com>, linux-kernel@...r.kernel.org,
	Dominique Toupin <dominique.toupin@...csson.com>,
	Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
	Tom Zanussi <tzanussi@...il.com>,
	Jeremie Galarneau <jgalar@...icios.com>,
	David Ahern <dsahern@...il.com>,
	Arnaldo Carvalho de Melo <acme@...hat.com>
Subject: Re: FW: [RFC 0/5] perf tools: Add perf data CTF conversion

On 2014-11-05 10:25 PM, Alexandre Montplaisir wrote:
>
>>
>>> But if you could for example tell me the perf equivalents of all the
>>> strings in that file, I could hack together such wrapper. With that,
>>> in theory, perf traces should behave exactly the same as LTTng traces
>>> in the viewer!
>> Oooh, that would be awesome. So I installed maven but didn't get much
>> further. Let me gather this for you.
>
> Awesome, thanks!
>
> I am travelling this week, so I'm a bit busy, but I will try to 
> prototype a "wrapper" for the kernel analysis, and adding support for 
> the perf events, whenever I have a chance. I'll keep you posted.

Ok, some good news!

I managed to get the CTF traces from perf working in Trace Compass! See 
attached screenshots. This is showing the "ctf-out2" trace from your 
previous email. The other trace seems to have less events enabled, so it 
would only show some WAIT_FOR_CPU states in the view.

If anybody wishes to try it, you can grab the whole branch ending at 
https://git.eclipse.org/r/#/c/36200/ . Or run:
$ git fetch 
git://git.eclipse.org/gitroot/tracecompass/org.eclipse.tracecompass 
refs/changes/00/36200/3 && git checkout FETCH_HEAD

It reuses much of the code from the LTTng analysis, which is why it was 
relatively quick to do. For now, it looks for the domain in the CTF 
environment to be "kernel-perf". But this will be easy to update, if 
needed, once the final format is decided.

Maybe I missed it, but I couldn't find the system call names in the 
trace. Using the sys_enter and sys_exit events, the viewer is able to 
determine the kernel-mode states (in blue), but we cannot show the exact 
system call names like we do with LTTng.
There is also something weird with the arrows in the Control Flow View 
(disabled in the screenshot), I don't know if it's due to the 
particularity of the trace or to a bug in the view. We'll investigate.

Feedback is very welcome.

Cheers,
Alexandre

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