From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932758AbXBSWcV (ORCPT ); Mon, 19 Feb 2007 17:32:21 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932759AbXBSWcV (ORCPT ); Mon, 19 Feb 2007 17:32:21 -0500 Received: from madara.hpl.hp.com ([192.6.19.124]:52533 "EHLO madara.hpl.hp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932758AbXBSWcU (ORCPT ); Mon, 19 Feb 2007 17:32:20 -0500 Date: Mon, 19 Feb 2007 14:32:06 -0800 From: Stephane Eranian To: linux-kernel@vger.kernel.org Cc: ak@suse.de, akpm@linux-foundation.org Subject: Re: [PATCH] i386 make NMI use PERFCTR1 for architectural perfmon (take 2) Message-ID: <20070219223206.GA30469@frankl.hpl.hp.com> Reply-To: eranian@hpl.hp.com References: <20070217160656.GA16715@frankl.hpl.hp.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20070217160656.GA16715@frankl.hpl.hp.com> User-Agent: Mutt/1.4.1i Organisation: HP Labs Palo Alto Address: HP Labs, 1U-17, 1501 Page Mill road, Palo Alto, CA 94304, USA. E-mail: eranian@hpl.hp.com X-HPL-MailScanner: Found to be clean X-HPL-MailScanner-From: eranian@hpl.hp.com Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Hello, This patch against 2.6.20-git14 makes the NMI watchdog use PERFSEL1/PERFCTR1 instead of PERFSEL0/PERFCTR0 on processors supporting Intel architectural perfmon, such as Intel Core 2. Although all PMU events can work on both counters, the Precise Event-Based Sampling (PEBS) requires that the event be in PERFCTR0 to work correctly (see section 18.14.4.1 in the IA32 SDM Vol 3b). A similar patch for x86-64 is to follow. Changelog: - make the i386 NMI watchdog use PERFSEL1/PERFCTR1 instead of PERFSEL0/PERFCTR0 on processors supporting the Intel architectural perfmon (e.g. Core 2 Duo). This allows PEBS to work when the NMI watchdog is active. signed-off-by: stephane eranian diff -urNp --exclude=.git linux-2.6.20.orig/arch/i386/kernel/nmi.c linux-2.6.20.base/arch/i386/kernel/nmi.c --- linux-2.6.20.orig/arch/i386/kernel/nmi.c 2007-02-19 13:37:26.000000000 -0800 +++ linux-2.6.20.base/arch/i386/kernel/nmi.c 2007-02-19 13:54:42.000000000 -0800 @@ -307,7 +307,7 @@ static int __init check_nmi_watchdog(voi nmi_hz = 1; if (wd->perfctr_msr == MSR_P6_PERFCTR0 || - wd->perfctr_msr == MSR_ARCH_PERFMON_PERFCTR0) { + wd->perfctr_msr == MSR_ARCH_PERFMON_PERFCTR1) { nmi_hz = adjust_for_32bit_ctr(nmi_hz); } } @@ -741,8 +741,8 @@ static int setup_intel_arch_watchdog(voi (ebx & ARCH_PERFMON_UNHALTED_CORE_CYCLES_PRESENT)) goto fail; - perfctr_msr = MSR_ARCH_PERFMON_PERFCTR0; - evntsel_msr = MSR_ARCH_PERFMON_EVENTSEL0; + perfctr_msr = MSR_ARCH_PERFMON_PERFCTR1; + evntsel_msr = MSR_ARCH_PERFMON_EVENTSEL1; if (!reserve_perfctr_nmi(perfctr_msr)) goto fail; @@ -1022,7 +1022,7 @@ __kprobes int nmi_watchdog_tick(struct p write_watchdog_counter(wd->perfctr_msr, NULL); } else if (wd->perfctr_msr == MSR_P6_PERFCTR0 || - wd->perfctr_msr == MSR_ARCH_PERFMON_PERFCTR0) { + wd->perfctr_msr == MSR_ARCH_PERFMON_PERFCTR1) { /* P6 based Pentium M need to re-unmask * the apic vector but it doesn't hurt * other P6 variant.