From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752018Ab1HOS2I (ORCPT ); Mon, 15 Aug 2011 14:28:08 -0400 Received: from terminus.zytor.com ([198.137.202.10]:57659 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751722Ab1HOS2G (ORCPT ); Mon, 15 Aug 2011 14:28:06 -0400 Message-ID: <4E4964F1.1020900@zytor.com> Date: Mon, 15 Aug 2011 11:26:57 -0700 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:5.0) Gecko/20110707 Thunderbird/5.0 MIME-Version: 1.0 To: Andrew Lutomirski CC: Borislav Petkov , melwyn lobo , Denys Vlasenko , Ingo Molnar , linux-kernel@vger.kernel.org, Thomas Gleixner , Linus Torvalds , Peter Zijlstra , borislav.petkov@amd.com Subject: Re: x86 memcpy performance References: <4E493449.70907@mit.edu> <4E494557.8080708@zytor.com> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 08/15/2011 09:58 AM, Andrew Lutomirski wrote: > On Mon, Aug 15, 2011 at 12:12 PM, H. Peter Anvin wrote: >> On 08/15/2011 08:36 AM, Andrew Lutomirski wrote: >>> >>> (*) kernel_fpu_begin is a bad name. It's only safe to use integer >>> instructions inside a kernel_fpu_begin section because MXCSR (and the >>> 387 equivalent) could contain garbage. >>> >> >> Uh... no, it just means you have to initialize the settings. It's a >> perfectly good name, it's called kernel_fpu_begin, not kernel_fp_begin. > > I prefer get_xstate / put_xstate, but this could rapidly devolve into > bikeshedding. :) > a) Quite. b) xstate is not architecture-neutral. -hpa