From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751532Ab2GZFu2 (ORCPT ); Thu, 26 Jul 2012 01:50:28 -0400 Received: from mx1.redhat.com ([209.132.183.28]:6932 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751011Ab2GZFu1 (ORCPT ); Thu, 26 Jul 2012 01:50:27 -0400 Date: Thu, 26 Jul 2012 08:50:11 +0300 From: Gleb Natapov To: Peter Zijlstra Cc: Robert Richter , David Ahern , Arnaldo Carvalho de Melo , linux-kernel@vger.kernel.org, Ingo Molnar , Jiri Olsa , Namhyung Kim , Frederic Weisbecker Subject: Re: [PATCH 08/11] perf tool: precise mode requires exclude_guest Message-ID: <20120726055011.GP26120@redhat.com> References: <1342826756-64663-1-git-send-email-dsahern@gmail.com> <1342826756-64663-9-git-send-email-dsahern@gmail.com> <20120723181358.GC6717@infradead.org> <500EAF23.8060909@gmail.com> <20120724161507.GG3732@erda.amd.com> <1343248546.26034.68.camel@twins> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1343248546.26034.68.camel@twins> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jul 25, 2012 at 10:35:46PM +0200, Peter Zijlstra wrote: > On Tue, 2012-07-24 at 18:15 +0200, Robert Richter wrote: > > David, > > > > On 24.07.12 08:20:19, David Ahern wrote: > > > On 7/23/12 12:13 PM, Arnaldo Carvalho de Melo wrote: > > > > Em Fri, Jul 20, 2012 at 05:25:53PM -0600, David Ahern escreveu: > > > >> PEBS cannot be used with guest mode. If user adds :p modifier set > > > >> exclude_guest as well. > > > > > > > > Is this something Intel specific? Or can someone think of an arch where > > > > this limitation wouldn't exist? > > > > > > Good point. So far precise_ip is used by arch/x86 only. I don't have an > > > AMD based server so I don't know if there is a conflict between > > > virtualization and IBS. Added Robert for advice. > > > > thanks for this hint. > > > > On AMD cpus precise_ip maps to IBS, which does not support hardware > > options as perfctrs do. Thus, following attr flags are not supported: > > > > exclude_user, exclude_kernel, exclude_host, exclude_guest > > > > Counting in guest mode is possible with IBS, but not the exclusion of > > a certain mode. If precise_ip counting is enabled on AMD we may not > > set the exclude_guest flag. > > IIRC we have SVM enter/exit hooks in kvm/perf already, we could use > those to implement exclude_guest for IBS. > > Now I've been trying to find the patches that introduced that, but I'm > failing horridly. Gleb, got us a pointer here? The commit is 144d31e6, but it introduces hook that is used on VMX only. SVM does not need it to implement guest/host only counters since it has HW support for that in the PMU. -- Gleb.