linux-kernel - Re: Perf record format portability

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Date:	Wed, 16 May 2012 14:50:31 +0400
From:	Dmitry Antipov <dmitry.antipov@...aro.org>
To:	Arnaldo Carvalho de Melo <acme@...stprotocols.net>
CC:	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Paul Mackerras <paulus@...ba.org>,
	Ingo Molnar <mingo@...hat.com>,
	Amit Kucheria <amit.kucheria@...aro.org>,
	linaro-dev@...ts.linaro.org, linux-kernel@...r.kernel.org
Subject: Re: Perf record format portability

On 05/15/2012 07:51 PM, Arnaldo Carvalho de Melo wrote:
> Em Tue, May 15, 2012 at 07:27:39PM +0400, Dmitry Antipov escreveu:
>> Hello,
>>
>> are there any thoughts on how much of the perf.data is portable and how much it should be?
>> I'm interesting in recording scheduler activity on one machine and then replaying on
>> another. As I can see, replaying x86 perf.data on ARM doesn't work. At least, should it
>> work with a small subset of recorded events (for example, sched:sched_switch,
>> sched:sched_process_exit, sched:sched_process_fork, sched:sched_wakeup
>> and sched:sched_migrate_task) on the same architecture?
>
> Endianness issues? ARM EB? There are some patches by Jiri Olsa that may
> help you if that is the case.

Thanks, will look at.

> It should be portable, are you using 'perf archive' too?

It doesn't work with cryptic messages like:

tar: .build-id/17/d6ca02b2c31df54bf62a4142c47e3c99a9eedf: Cannot stat: No such file or directory

creating empty archive.

> What exactly is the error experienced?

Now I'm facing the simple problem with event IDs, which may be different from machine to
machine. For example, /sys/kernel/debug/tracing/events/sched/sched_switch/id is 55 on my ARM
board and 279 on my PC host, so 'perf report' displays all event names like "unknown:unknown",
even with --kallsyms=XXX where XXX is 'cat /proc/kallsyms > XXX' from PC host.

Dmitry

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