From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932759AbXBSWeN (ORCPT ); Mon, 19 Feb 2007 17:34:13 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932761AbXBSWeN (ORCPT ); Mon, 19 Feb 2007 17:34:13 -0500 Received: from madara.hpl.hp.com ([192.6.19.124]:52693 "EHLO madara.hpl.hp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932759AbXBSWeM (ORCPT ); Mon, 19 Feb 2007 17:34:12 -0500 Date: Mon, 19 Feb 2007 14:34:00 -0800 From: Stephane Eranian To: linux-kernel@vger.kernel.org Cc: ak@suse.de, akpm@linux-foundation.org Subject: Re: [PATCH] x86_64 make NMI use PERFCTR1 for architectural perfmon (take 2) Message-ID: <20070219223400.GB30469@frankl.hpl.hp.com> Reply-To: eranian@hpl.hp.com References: <20070217160838.GB16715@frankl.hpl.hp.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20070217160838.GB16715@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). This versions has 3 chunks compared to previous where we had missed on check. Changelog: - make the x86-64 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/x86_64/kernel/nmi.c linux-2.6.20.base/arch/x86_64/kernel/nmi.c --- linux-2.6.20.orig/arch/x86_64/kernel/nmi.c 2007-02-19 13:37:27.000000000 -0800 +++ linux-2.6.20.base/arch/x86_64/kernel/nmi.c 2007-02-19 14:27:45.000000000 -0800 @@ -285,7 +285,7 @@ int __init check_nmi_watchdog (void) struct nmi_watchdog_ctlblk *wd = &__get_cpu_var(nmi_watchdog_ctlblk); nmi_hz = 1; - if (wd->perfctr_msr == MSR_ARCH_PERFMON_PERFCTR0) + if (wd->perfctr_msr == MSR_ARCH_PERFMON_PERFCTR1) nmi_hz = adjust_for_32bit_ctr(nmi_hz); } @@ -650,8 +650,8 @@ 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; @@ -895,7 +895,7 @@ int __kprobes nmi_watchdog_tick(struct p /* start the cycle over again */ wrmsrl(wd->perfctr_msr, -((u64)cpu_khz * 1000 / nmi_hz)); - } else if (wd->perfctr_msr == MSR_ARCH_PERFMON_PERFCTR0) { + } else if (wd->perfctr_msr == MSR_ARCH_PERFMON_PERFCTR1) { /* * ArchPerfom/Core Duo needs to re-unmask * the apic vector