From mboxrd@z Thu Jan 1 00:00:00 1970 From: Frederic Weisbecker Subject: Re: [PATCH 1/2] perf tools: Add reference timestamp to perf header Date: Mon, 13 Dec 2010 18:23:52 +0100 Message-ID: <20101213172349.GD1691@nowhere> References: <1291773285-16254-1-git-send-email-daahern@cisco.com> <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> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mail-fx0-f43.google.com ([209.85.161.43]:57344 "EHLO mail-fx0-f43.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752611Ab0LMRX5 (ORCPT ); Mon, 13 Dec 2010 12:23:57 -0500 Content-Disposition: inline In-Reply-To: <1292260419.6803.300.camel@twins> Sender: linux-perf-users-owner@vger.kernel.org List-ID: To: Peter Zijlstra Cc: Arnaldo Carvalho de Melo , "David S. Ahern" , linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org 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? But perf.data on UP will be sensibly the same as today so I suspect we won't need to be compatible. But I guess I am missing something, in which case that probably doesn't change much the picture. It's not because one day we'll need to break the format that we can happily do so everyday. Backward compatibility is important and we should preserve it when it's possible.