From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759676AbZJHUeW (ORCPT ); Thu, 8 Oct 2009 16:34:22 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757112AbZJHUeV (ORCPT ); Thu, 8 Oct 2009 16:34:21 -0400 Received: from mail-ew0-f208.google.com ([209.85.219.208]:64204 "EHLO mail-ew0-f208.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757008AbZJHUeU (ORCPT ); Thu, 8 Oct 2009 16:34:20 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=date:from:to:cc:subject:message-id:references:mime-version :content-type:content-disposition:in-reply-to:user-agent; b=tqiEMrt+toWpEpUYiuX9zoMzf6ua7lOZsujqmLv8Ehd++d1YcBDAJUUMRIMB145sPC eEuFbddqQZV8HvVUBFjB2kUuFf1DphV3C7V6o2aL8lD+K3TCsj3KHB4u9/00fiTl4Lux zi9f631gErb3JOUDs4gCoi6KgQ4GWSD0dLdzk= Date: Thu, 8 Oct 2009 22:28:30 +0200 From: Frederic Weisbecker To: Ingo Molnar Cc: LKML , Peter Zijlstra , Arnaldo Carvalho de Melo , Mike Galbraith , Paul Mackerras Subject: Re: [PATCH] perf tools: Provide backward compatibility with previous perf.data version Message-ID: <20091008202828.GF5073@nowhere> References: <1255032449-12022-1-git-send-email-fweisbec@gmail.com> <20091008201222.GB30594@elte.hu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20091008201222.GB30594@elte.hu> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Oct 08, 2009 at 10:12:22PM +0200, Ingo Molnar wrote: > > * Frederic Weisbecker wrote: > > > We have merged the trace.info file into perf.data by adding one > > section in the perf headers. This makes it incompatible with previous > > version: the new perf tools can't read the older perf.data. > > > > To support the previous format, we check the headers size. If they > > have the same size than in the previous format, then ignore the trace > > info section that doesn't exist. > > > > Signed-off-by: Frederic Weisbecker > > Cc: Peter Zijlstra > > Cc: Arnaldo Carvalho de Melo > > Cc: Mike Galbraith > > Cc: Paul Mackerras > > --- > > tools/perf/util/header.c | 8 +++++++- > > 1 files changed, 7 insertions(+), 1 deletions(-) > > > > diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c > > index 212fade..9aae360 100644 > > --- a/tools/perf/util/header.c > > +++ b/tools/perf/util/header.c > > @@ -287,10 +287,16 @@ struct perf_header *perf_header__read(int fd) > > do_read(fd, &f_header, sizeof(f_header)); > > > > if (f_header.magic != PERF_MAGIC || > > - f_header.size != sizeof(f_header) || > > f_header.attr_size != sizeof(f_attr)) > > die("incompatible file format"); > > > > + if (f_header.size != sizeof(f_header)) { > > + /* Support the previous format */ > > + if (f_header.size == offsetof(typeof(f_header), trace_info)) > > + f_header.trace_info.size = 0; > > + else > > + die("incompatible file format"); > > + } > > nr_attrs = f_header.attrs.size / sizeof(f_attr); > > lseek(fd, f_header.attrs.offset, SEEK_SET); > > Perfect - thanks Frederic! > > This should handle most of the (non-trace) perf.data's out there. Yeah, hopefully. I've only tested in a simple old perf.data but that should do the trick for all of the non-trace files. > trace.info is not something we really want to be backwards compatible > about, if we can avoid it. > > Ingo Yeah, that said, it's still possible and wouldn't require too much changes. May be let's wait for complaints and, if any, I can provide this backward support too. Thanks.