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Date: Mon, 13 Dec 2010 18:50:06 +0100
From: Frederic Weisbecker <fweisbec@gmail.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>,
        "David S. Ahern" <daahern@cisco.com>, linux-perf-users@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/2] perf tools: Add reference timestamp to perf header
Message-ID: <20101213174959.GE1691@nowhere>
References: <1291773285-16254-2-git-send-email-daahern@cisco.com>
 <20101212201613.GA1784@nowhere>
 <4D06301C.2090309@cisco.com>
 <20101213155451.GA1691@nowhere>
 <20101213164854.GL5407@ghostprotocols.net>
 <20101213170923.GB1691@nowhere>
 <1292260289.6803.297.camel@twins>
 <1292260419.6803.300.camel@twins>
 <20101213172349.GD1691@nowhere>
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On Mon, Dec 13, 2010 at 06:37:40PM +0100, Peter Zijlstra wrote:
> On Mon, 2010-12-13 at 18:23 +0100, Frederic Weisbecker wrote:
> > On Mon, Dec 13, 2010 at 06:13:39PM +0100, Peter Zijlstra wrote:
> > > On Mon, 2010-12-13 at 18:11 +0100, Peter Zijlstra wrote:
> > > > 
> > > > Preferably, yes, but I don't see why we can't break the data file format
> > > > if we've got good reasons to. 
> > > 
> > > I mean, we pretty much _have_ to break data file format when we want to
> > > do splice() support.
> > 
> > Because we'll have one file per-cpu?
> 
> Right.
> 
> > But perf.data on UP will be sensibly the same as today so I suspect
> > we won't need to be compatible.
> 
> Nope, since one file simply doesn't scale, data-streams will have to
> live outside of the main file.
> 
> And when you have to make that happen, there is no reason to maintain
> any kind of compatibility. The only thing you could do is provide some
> script to convert old data files to the new format.

Right, a script should do the trick.
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