From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S1752771Ab2GYUgU (ORCPT <rfc822;w@1wt.eu>);
	Wed, 25 Jul 2012 16:36:20 -0400
Received: from merlin.infradead.org ([205.233.59.134]:49911 "EHLO
	merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
	with ESMTP id S1752344Ab2GYUgT convert rfc822-to-8bit (ORCPT
	<rfc822;linux-kernel@vger.kernel.org>);
	Wed, 25 Jul 2012 16:36:19 -0400
Message-ID: <1343248546.26034.68.camel@twins>
Subject: Re: [PATCH 08/11] perf tool: precise mode requires exclude_guest
From: Peter Zijlstra <peterz@infradead.org>
To: Robert Richter <robert.richter@amd.com>
Cc: David Ahern <dsahern@gmail.com>,
        Arnaldo Carvalho de Melo <acme@ghostprotocols.net>,
        linux-kernel@vger.kernel.org, Ingo Molnar <mingo@kernel.org>,
        Jiri Olsa <jolsa@redhat.com>, Namhyung Kim <namhyung@kernel.org>,
        Frederic Weisbecker <fweisbec@gmail.com>,
        Gleb Natapov <gleb@redhat.com>
Date: Wed, 25 Jul 2012 22:35:46 +0200
In-Reply-To: <20120724161507.GG3732@erda.amd.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>
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7BIT
X-Mailer: Evolution 3.2.2- 
Mime-Version: 1.0
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

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?