Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757578Ab1FQIGj (ORCPT ); Fri, 17 Jun 2011 04:06:39 -0400 Received: from mx2.mail.elte.hu ([157.181.151.9]:56740 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753512Ab1FQIGc (ORCPT ); Fri, 17 Jun 2011 04:06:32 -0400 Date: Fri, 17 Jun 2011 10:06:18 +0200 From: Ingo Molnar To: Robert Richter Cc: Peter Zijlstra , LKML , oprofile-list , "Suthikulpanit, Suravee" Subject: Re: [PATCH] oprofile, x86: Fix race in nmi handler while starting Message-ID: <20110617080618.GA893@elte.hu> References: <1307465249-20055-1-git-send-email-robert.richter@amd.com> <20110609071854.GE20544@elte.hu> <20110616152531.GR20052@erda.amd.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20110616152531.GR20052@erda.amd.com> User-Agent: Mutt/1.5.20 (2009-08-17) X-ELTE-SpamScore: -2.0 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-2.0 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.3.1 -2.0 BAYES_00 BODY: Bayes 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 Content-Length: 1602 Lines: 41 * Robert Richter wrote: > On 09.06.11 03:18:54, Ingo Molnar wrote: > > > > * Robert Richter wrote: > > > > > In some rare cases, nmis are generated immediately after the > > > nmi handler of the cpu was started. This causes the counter not > > > to be enabled. Before enabling the nmi handlers we need to set > > > variable ctr_running first and make sure its value is written > > > to memory. > > > > > > Also, the patch makes all existing barriers a memory barrier > > > instead of a compiler barrier only. > > > > Could we *PLEASE* just do the obvious and turn oprofile into a > > perf user on x86 too, like ARM already does? Two years down the > > line and there's zero progress in that area. We want to obsolete > > the Oprofile PMU bits on x86, the infrastructure duplication > > causes non-trivial problems like this one. > > Ingo, > > I would rather prefer to spend the effort to add full pmu support > to perf. AMD features missing are still IBS and nb performance > counters for family 15h. The oprofile kernel driver would become > obsolete at all with a new daemon using the perf syscall interface. Agreed - i just don't see *any* progress on the IBS front: more time seems to be spent on fixing and sometimes even extending oprofile than on any IBS work. Thanks, Ingo -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/