Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754307AbZIUHcu (ORCPT ); Mon, 21 Sep 2009 03:32:50 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752037AbZIUHcs (ORCPT ); Mon, 21 Sep 2009 03:32:48 -0400 Received: from mx3.mail.elte.hu ([157.181.1.138]:47477 "EHLO mx3.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751613AbZIUHcs (ORCPT ); Mon, 21 Sep 2009 03:32:48 -0400 Date: Mon, 21 Sep 2009 09:32:32 +0200 From: Ingo Molnar To: "Metzger, Markus T" Cc: "hpa@zytor.com" , "linux-kernel@vger.kernel.org" , "a.p.zijlstra@chello.nl" , "tglx@linutronix.de" , "mingo@redhat.com" , "linux-tip-commits@vger.kernel.org" Subject: Re: [tip:perfcounters/core] x86, perf_counter, bts: Optimize BTS overflow handling Message-ID: <20090921073232.GC24467@elte.hu> References: <20090915130023.A16204@sedona.ch.intel.com> <928CFBE8E7CB0040959E56B4EA41A77EC69BA609@irsmsx504.ger.corp.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <928CFBE8E7CB0040959E56B4EA41A77EC69BA609@irsmsx504.ger.corp.intel.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 Content-Length: 2288 Lines: 54 * Metzger, Markus T wrote: > >-----Original Message----- > >From: tip tree robot [mailto:bounces.tip@hpa.at.zytor.com] On Behalf Of tip-bot for Markus Metzger > >Sent: Friday, September 18, 2009 9:19 PM > >To: linux-tip-commits@vger.kernel.org > >Cc: linux-kernel@vger.kernel.org; hpa@zytor.com; mingo@redhat.com; a.p.zijlstra@chello.nl; Metzger, > >Markus T; tglx@linutronix.de; mingo@elte.hu > >Subject: [tip:perfcounters/core] x86, perf_counter, bts: Optimize BTS overflow handling > > > >Commit-ID: 5622f295b53fb60dbf9bed3e2c89d182490a8b7f > >Gitweb: http://git.kernel.org/tip/5622f295b53fb60dbf9bed3e2c89d182490a8b7f > >Author: Markus Metzger > >AuthorDate: Tue, 15 Sep 2009 13:00:23 +0200 > >Committer: Ingo Molnar > >CommitDate: Fri, 18 Sep 2009 20:43:20 +0200 > > > >x86, perf_counter, bts: Optimize BTS overflow handling > > > >Draining the BTS buffer on a buffer overflow interrupt takes too > >long resulting in a kernel lockup when tracing the kernel. > > > >Restructure perf_counter sampling into sample creation and sample > >output. > > > >Prepare a single reference sample for BTS sampling and update the > >from and to address fields when draining the BTS buffer. Drain the > >entire BTS buffer between a single perf_output_begin() / > >perf_output_end() pair. > > > >Signed-off-by: Markus Metzger > >Signed-off-by: Peter Zijlstra > >LKML-Reference: <20090915130023.A16204@sedona.ch.intel.com> > >Signed-off-by: Ingo Molnar > > > Ingo, > > This change should speed up BTS overflow handling enough to support > branch tracing the kernel. > Would you please drop 1653192f510bd8114b7b133d7289e6e5c3e95046 > that disabled kernel tracing to work around the issue. Please send a proper patch that re-enables the (previously unreliable) aspect of BTS tracing, with a changelog that explains that the feature now works and with an indication that you've tested it. 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/