From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755071AbZKIJ0O (ORCPT ); Mon, 9 Nov 2009 04:26:14 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755005AbZKIJ0O (ORCPT ); Mon, 9 Nov 2009 04:26:14 -0500 Received: from one.firstfloor.org ([213.235.205.2]:48020 "EHLO one.firstfloor.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754264AbZKIJ0N (ORCPT ); Mon, 9 Nov 2009 04:26:13 -0500 To: "H. Peter Anvin" Cc: "Ma, Ling" , Ingo Molnar , Thomas Gleixner , linux-kernel Subject: Re: [PATCH RFC] [X86] performance improvement for memcpy_64.S by fast string. From: Andi Kleen References: <1257500482-16182-1-git-send-email-ling.ma@intel.com> <4AF457E0.4040107@zytor.com> <4AF4784C.5090800@zytor.com> <8FED46E8A9CA574792FC7AACAC38FE7714FCF772C9@PDSMSX501.ccr.corp.intel.com> <4AF7C66C.6000009@zytor.com> Date: Mon, 09 Nov 2009 10:26:14 +0100 In-Reply-To: <4AF7C66C.6000009@zytor.com> (H. Peter Anvin's message of "Sun, 08 Nov 2009 23:36:12 -0800") Message-ID: <87ws2059s9.fsf@basil.nowhere.org> User-Agent: Gnus/5.1008 (Gnus v5.10.8) Emacs/22.3 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org "H. Peter Anvin" writes: > > My personal opinion is that if we can show no significant slowdown on > P4, K8, P-M/Core 1, Core 2, and Nehalem then we can simply use this code The issue is Core 2. P4 uses a different path, and Core 1 doesn't use the 64bit code. > unconditionally. If one of them is radically worse than baseline, then > we have to do something conditional, which is a lot more complicated. I have an older patchkit which did this, and some more optimizations to this code. There was still one open issue, that is why I didn't post it. If there's interest I can post it. -Andi -- ak@linux.intel.com -- Speaking for myself only.