From mboxrd@z Thu Jan 1 00:00:00 1970 From: Joerg Roedel Subject: Re: KVM PMU virtualization Date: Fri, 26 Feb 2010 11:39:34 +0100 Message-ID: <20100226103934.GD4246@8bytes.org> References: <4B86917C.4070102@redhat.com> <20100225173423.GB4246@8bytes.org> <20100226084241.GF15885@elte.hu> <4B87987A.2020302@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Ingo Molnar , Jes Sorensen , KVM General , Peter Zijlstra , Zachary Amsden , Gleb Natapov , ming.m.lin@intel.com, "Zhang, Yanmin" , Peter Zijlstra , Thomas Gleixner , "H. Peter Anvin" , Arjan van de Ven , Fr??d??ric Weisbecker , Arnaldo Carvalho de Melo To: Avi Kivity Return-path: Received: from 8bytes.org ([88.198.83.132]:34204 "EHLO 8bytes.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933898Ab0BZKjf (ORCPT ); Fri, 26 Feb 2010 05:39:35 -0500 Content-Disposition: inline In-Reply-To: <4B87987A.2020302@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: On Fri, Feb 26, 2010 at 11:46:34AM +0200, Avi Kivity wrote: > On 02/26/2010 10:42 AM, Ingo Molnar wrote: >> Note that the 'soft PMU' still sucks from a design POV as there's no generic >> hw interface to the PMU. So there would have to be a 'soft AMD' and a 'soft >> Intel' PMU driver at minimum. >> > > Right, this will severely limit migration domains to hosts of the same > vendor and processor generation. There is a middle ground, though, > Intel has recently moved to define an "architectural pmu" which is not > model specific. I don't know if AMD adopted it. We could offer both > options - native host capabilities, with a loss of compatibility, and > the architectural pmu, with loss of model specific counters. I only had a quick look yet on the architectural pmu from intel but it looks like it can be emulated for a guest on amd using existing features. Joerg