From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756064AbZEJGxm (ORCPT ); Sun, 10 May 2009 02:53:42 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752210AbZEJGx1 (ORCPT ); Sun, 10 May 2009 02:53:27 -0400 Received: from hera.kernel.org ([140.211.167.34]:34850 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751510AbZEJGxZ (ORCPT ); Sun, 10 May 2009 02:53:25 -0400 Subject: Re: [tip:perfcounters/core] perf_counter, x86: remove X86_FEATURE_ARCH_PERFMON flag for AMD cpus From: Jaswinder Singh Rajput To: Ingo Molnar Cc: mingo@redhat.com, hpa@zytor.com, paulus@samba.org, linux-kernel@vger.kernel.org, robert.richter@amd.com, a.p.zijlstra@chello.nl, tglx@linutronix.de, linux-tip-commits@vger.kernel.org In-Reply-To: <20090510063047.GD30778@elte.hu> References: <1241002046-8832-2-git-send-email-robert.richter@amd.com> <1241931753.4796.15.camel@localhost.localdomain> <1241934795.4796.55.camel@localhost.localdomain> <20090510063047.GD30778@elte.hu> Content-Type: text/plain Date: Sun, 10 May 2009 12:21:50 +0530 Message-Id: <1241938310.4796.67.camel@localhost.localdomain> Mime-Version: 1.0 X-Mailer: Evolution 2.24.5 (2.24.5-1.fc10) Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, 2009-05-10 at 08:30 +0200, Ingo Molnar wrote: > * Jaswinder Singh Rajput wrote: > > > > #define X86_FEATURE_ARCH_PERFMON (3*32+11) /* Intel Architectural PerfMon */ > > > should be replaced by > > > #define X86_FEATURE_ARCH_PERFMON (3*32+11) /* Performace Monitor */ > > > > > > All x86 cpus which support performance monitor should set this feature. > > > > > > > Currently X86_FEATURE_ARCH_PERFMON is enabled for >= Intel Core2 > > > > But Performance monitor is almost supported by all Intel > > processors. I am adding few MSRs list for reference to see > > complete list please check arch/x86/kernel/cpu/cpu_debug.c > > I think you are confusing two things: > > - The 'architectural perfmon' CPU flag, enumerated in CPUID. (this > is a relatively new CPUID flag that only Intel CPUs at around > Core2 and later will report.) > > - The concept of 'performance monitoring' - which has been present > in various x86 CPUs starting at the original Pentium (P5) 15 years > ago or so. > > The X86_FEATURE_ARCH_PERFMON flag is for the architectural perfmon > CPUID feature. If you execute CPUID you'll get that from the CPU - > on Core2 and later Intel CPUs. You wont get it on AMD CPUs. You wont > get it on earlier Intel CPUs. > > And since 'Architectural Performance Monitoring' is an Intel only > thing, it would not be correct to do as if AMD had the same thing. > AMD has something _similar_, but not quite the same. > Thanks for clarification. There is one more way to check performance monitor support for Intel by using IA32_MISC_ENABLE MSR (0x1A0) bit 7 tells whether performance monitoring is available or not. But IA32_MISC_ENABLE MSR (0x1A0) is not available for Pentium and P6. So better I will add new cpufeature for performance monitoring for x86: X86_FEATURE_PERFMON : Performance monitor support -- JSR