From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753418Ab3AYWLd (ORCPT ); Fri, 25 Jan 2013 17:11:33 -0500 Received: from terminus.zytor.com ([198.137.202.10]:47231 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751977Ab3AYWLb (ORCPT ); Fri, 25 Jan 2013 17:11:31 -0500 Message-ID: <510302FD.3090009@zytor.com> Date: Fri, 25 Jan 2013 14:11:09 -0800 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130110 Thunderbird/17.0.2 MIME-Version: 1.0 To: mingo@kernel.org, hpa@zytor.com, linux-kernel@vger.kernel.org, konrad.wilk@oracle.com, torvalds@linux-foundation.org, JBeulich@suse.com, jbeulich@suse.com, tglx@linutronix.de CC: linux-tip-commits@vger.kernel.org Subject: Re: [tip:x86/asm] x86/xor: Make virtualization friendly References: <5093E4F302000078000A6162@nat28.tlf.novell.com> In-Reply-To: X-Enigmail-Version: 1.5 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 01/25/2013 02:43 AM, tip-bot for Jan Beulich wrote: > Commit-ID: 05fbf4d6fc6a3c0c3e63b77979c9311596716d10 > Gitweb: http://git.kernel.org/tip/05fbf4d6fc6a3c0c3e63b77979c9311596716d10 > Author: Jan Beulich > AuthorDate: Fri, 2 Nov 2012 14:21:23 +0000 > Committer: Ingo Molnar > CommitDate: Fri, 25 Jan 2013 09:23:51 +0100 > > x86/xor: Make virtualization friendly > > In virtualized environments, the CR0.TS management needed here > can be a lot slower than anticipated by the original authors of > this code, which particularly means that in such cases forcing > the use of SSE- (or MMX-) based implementations is not desirable > - actual measurements should always be done in that case. > > For consistency, pull into the shared (32- and 64-bit) header > not only the inclusion of the generic code, but also that of the > AVX variants. > This patch is wrong and should be dropped. I verified it with the KVM people that they do NOT want this change. It is a Xen-specific problem. -hpa