Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752079AbaBET0P (ORCPT ); Wed, 5 Feb 2014 14:26:15 -0500 Received: from smtpauth02.mfg.siteprotect.com ([64.26.60.136]:60451 "EHLO smtpauth02.mfg.siteprotect.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751274AbaBET0L (ORCPT ); Wed, 5 Feb 2014 14:26:11 -0500 Date: Wed, 5 Feb 2014 14:29:36 -0500 (EST) From: Vince Weaver X-X-Sender: vince@pianoman.cluster.toy To: Peter Zijlstra cc: junk@eslaf.co.uk, alan@lxorguk.ukuu.org.uk, Ingo Molnar , Stephane Eranian , linux-kernel@vger.kernel.org Subject: Re: [PATCH] perf,x86,p6: Add userspace RDPMC quirk for P6 In-Reply-To: <20140205192012.GL2936@laptop.programming.kicks-ass.net> Message-ID: References: <20140205102718.GF3229@twins.programming.kicks-ass.net> <20140205192012.GL2936@laptop.programming.kicks-ass.net> User-Agent: Alpine 2.02 (DEB 1266 2009-07-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-CTCH-Spam: Unknown X-CTCH-RefID: str=0001.0A020202.52F29053.000F,ss=1,re=0.000,fgs=0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 5 Feb 2014, Peter Zijlstra wrote: > On Wed, Feb 05, 2014 at 02:16:43PM -0500, Vince Weaver wrote: > > On Wed, 5 Feb 2014, Peter Zijlstra wrote: > > > > > P6 class machines can die hard when PCE gets enabled due to CPU > > > errata. The safe way it so disable it by default and keep it disabled. > > > > > > See errata 26: > > > > so you take an errata applicable to a subset of Pentium Pro steppings and > > apply it to the whole p6 line (which includes the whole way up to Pentium > > III)? > > > > Or am I missing something in the documentation you link to? > > I forgot it went all the way to P-III, let me try and find the other > erratas. from the document you linked it looks like it was fixed by the Pentium Pro stepping sB1 (6.1.9). Has someone actually hit this bug? People used PAPI/perfctr on these machines for years, and it uses rdpmc by default so I would think it would show up if it were an issue. I should check the perfctr code to see if it had some sort of check. Vince -- 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/