From mboxrd@z Thu Jan 1 00:00:00 1970 From: Gleb Natapov Subject: Re: [PATCH] KVM: SVM: Pass through the host kernel's IO delay port Date: Mon, 22 Jun 2009 13:24:54 +0300 Message-ID: <20090622102454.GA15865@redhat.com> References: <1245406553-22013-1-git-send-email-pbonzini@redhat.com> <4A3F4F6F.6090209@redhat.com> <4A3F58EF.8010206@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Avi Kivity , kvm@vger.kernel.org To: Paolo Bonzini Return-path: Received: from mx2.redhat.com ([66.187.237.31]:34009 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750765AbZFVKYy (ORCPT ); Mon, 22 Jun 2009 06:24:54 -0400 Received: from int-mx2.corp.redhat.com (int-mx2.corp.redhat.com [172.16.27.26]) by mx2.redhat.com (8.13.8/8.13.8) with ESMTP id n5MAOv5W007668 for ; Mon, 22 Jun 2009 06:24:57 -0400 Content-Disposition: inline In-Reply-To: <4A3F58EF.8010206@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: On Mon, Jun 22, 2009 at 12:11:59PM +0200, Paolo Bonzini wrote: > Avi Kivity wrote: >> On 06/19/2009 01:15 PM, Paolo Bonzini wrote: >>> From: Paolo Bonzini >>> >>> KVM's optimization of guest port 80 accesses was removed last May 11 >>> in commit 99f85a. However, this probably has speed penalties. I don't >>> have a machine to test but the equivalent VMX patch (fdef3ad) reported >>> a speedup of 3-5%, and on the Xen mailing list it was mentioned that on >>> Xen passing port 80 through had positive effects on startup speed. >>> >>> We can enable passthrough to the same port the host kernel uses instead. >> >> Since we don't tell the guest to use 0xed, this won't help. > > Won't the guest do that automatically through DMI? > DMI that guest sees is very different from DMI of the host. What table is used to tell which port to use for io delay? -- Gleb.