From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752949Ab0CSAOs (ORCPT ); Thu, 18 Mar 2010 20:14:48 -0400 Received: from casper.infradead.org ([85.118.1.10]:55065 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752632Ab0CSAOr (ORCPT ); Thu, 18 Mar 2010 20:14:47 -0400 Subject: Re: [PATCH] perf_events: fix ordering bug in perf_output_sample() From: Peter Zijlstra To: Stephane Eranian Cc: linux-kernel@vger.kernel.org, mingo@elte.hu, paulus@samba.org, davem@davemloft.net, fweisbec@gmail.com, robert.richter@amd.com, perfmon2-devel@lists.sf.net, eranian@gmail.com In-Reply-To: References: <4ba2317a.8109cc0a.2858.ffffcd0c@mx.google.com> <1268937194.9440.373.camel@laptop> Content-Type: text/plain; charset="UTF-8" Date: Fri, 19 Mar 2010 01:14:40 +0100 Message-ID: <1268957680.9440.430.camel@laptop> Mime-Version: 1.0 X-Mailer: Evolution 2.28.3 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 2010-03-18 at 22:29 +0100, Stephane Eranian wrote: > On Thu, Mar 18, 2010 at 7:33 PM, Peter Zijlstra wrote: > > On Thu, 2010-03-18 at 14:42 +0200, Stephane Eranian wrote: > >> In order to parse a sample correctly based on the information > >> requested via sample_type, the kernel needs to save each component > >> in a known order. There is no type value saved with each component. > >> The current convention is that each component is saved according to > >> the order in enum perf_event_sample_format. But perf_output_sample() > >> was not completely following this convention, thereby making samples > >> impossible to parse without internal kernel knowledge. > >> > >> This patch puts things in the right order. > > > > NAK, not so actually, its in the order specified in the > > PERF_RECORD_SAMPLE comment. > > > And why is that order different than the one in the enum? Because I tried to keep the simple elements before the complex ones, but in any case its too late to change any ordering there now, as its ABI.