From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754806Ab0CDI5f (ORCPT ); Thu, 4 Mar 2010 03:57:35 -0500 Received: from bombadil.infradead.org ([18.85.46.34]:35616 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754740Ab0CDI5d (ORCPT ); Thu, 4 Mar 2010 03:57:33 -0500 Subject: Re: [RFC][PATCH 10/11] perf, x86: use LBR for PEBS IP+1 fixup From: Peter Zijlstra To: Stephane Eranian Cc: Masami Hiramatsu , mingo@elte.hu, linux-kernel@vger.kernel.org, paulus@samba.org, robert.richter@amd.com, fweisbec@gmail.com In-Reply-To: References: <20100303163936.906011640@chello.nl> <20100303164306.602529559@chello.nl> <4B8EA4D9.6000505@redhat.com> <1267645029.25158.106.camel@laptop> <4B8ED097.6090006@redhat.com> Content-Type: text/plain; charset="UTF-8" Date: Thu, 04 Mar 2010 09:57:26 +0100 Message-ID: <1267693046.25158.143.camel@laptop> Mime-Version: 1.0 X-Mailer: Evolution 2.28.2 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2010-03-03 at 22:50 +0100, Stephane Eranian wrote: > I think systematically and transparently using LBR to correct PEBS off-by-one > problem is not such a good idea. You've basically highjacked LBR and user > cannot use it in a different way. Well, they could, it just makes scheduling the stuff more interesting. > There are PEBS+LBR measurements where you care about extracting the LBR data. > There are PEBS measurements where you don't care about getting the correct IP. > I don't necessarily want to pay the price, especially when this could > be done offline in the tool. There are some people who argue that fixing up that +1 insn issue is critical, sadly they don't appear to want to argue their case in public. What we can do is make it optional I guess.