From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933498AbZJHUNN (ORCPT ); Thu, 8 Oct 2009 16:13:13 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756518AbZJHUNK (ORCPT ); Thu, 8 Oct 2009 16:13:10 -0400 Received: from mx3.mail.elte.hu ([157.181.1.138]:41628 "EHLO mx3.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755772AbZJHUNJ (ORCPT ); Thu, 8 Oct 2009 16:13:09 -0400 Date: Thu, 8 Oct 2009 22:12:22 +0200 From: Ingo Molnar To: Frederic Weisbecker 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: <20091008201222.GB30594@elte.hu> References: <1255032449-12022-1-git-send-email-fweisbec@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1255032449-12022-1-git-send-email-fweisbec@gmail.com> User-Agent: Mutt/1.5.18 (2008-05-17) X-ELTE-SpamScore: -1.5 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-1.5 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.2.5 -1.5 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * 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. trace.info is not something we really want to be backwards compatible about, if we can avoid it. Ingo