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From: Ingo Molnar <mingo@elte.hu>
To: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
	Arnaldo Carvalho de Melo <acme@redhat.com>,
	Paul Mackerras <paulus@samba.org>, Mike Galbraith <efault@gmx.de>,
	LKML <linux-kernel@vger.kernel.org>
Subject: Re: [RFC][PATCH] perf tools: Merge trace.info content into perf.data
Date: Wed, 7 Oct 2009 08:22:04 +0200	[thread overview]
Message-ID: <20091007062204.GE21673@elte.hu> (raw)
In-Reply-To: <20091006213643.GA5343@nowhere>


* Frederic Weisbecker <fweisbec@gmail.com> wrote:

> Hi,
> 
> Here is an attempt to remove the trace.info file. It works well for 
> me, the reason for it to be an RFC is that I have doubts about the 
> backward compatibility.
> 
> A file created by perf after his patch is unsupported by previous 
> version because the size of the headers have increased.

That's OK i think in terms of trace.info - trace.info was a temporary 
hack to begin with.

> That said, it's two new fields that have been added in the end of the 
> headers, and those could be ignored by previous versions if they just 
> handled the dynamic header size and then ignore the unknow part. The 
> offsets guarantee the compatibility.

Yes, that's how it should work.

> But previous versions handle the header size using its static size, 
> not dynamic, then it's not backward compatible.
> 
> Anyway, I'm not sure exactly how to handle that.

That's a bug in the previous version - mind doing a standalone fix for 
that so we can mark it Cc: stable?

Thanks,

	Ingo

  reply	other threads:[~2009-10-07  6:23 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-10-06 21:36 [RFC][PATCH] perf tools: Merge trace.info content into perf.data Frederic Weisbecker
2009-10-07  6:22 ` Ingo Molnar [this message]
2009-10-07  6:43   ` Ingo Molnar
2009-10-07  8:18     ` Frederic Weisbecker
2009-10-07  8:11   ` Frederic Weisbecker
2009-10-07  6:47 ` Peter Zijlstra
2009-10-07  8:20   ` Frederic Weisbecker
2009-10-07  7:31 ` [tip:perf/core] " tip-bot for Frederic Weisbecker

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