From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262711AbTDRASA (ORCPT ); Thu, 17 Apr 2003 20:18:00 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262710AbTDRAR7 (ORCPT ); Thu, 17 Apr 2003 20:17:59 -0400 Received: from neon-gw-l3.transmeta.com ([63.209.4.196]:36613 "EHLO neon-gw.transmeta.com") by vger.kernel.org with ESMTP id S262689AbTDRAR6 (ORCPT ); Thu, 17 Apr 2003 20:17:58 -0400 To: linux-kernel@vger.kernel.org From: "H. Peter Anvin" Subject: Re: [BK+PATCH] remove __constant_memcpy Date: 17 Apr 2003 17:29:23 -0700 Organization: Transmeta Corporation, Santa Clara CA Message-ID: References: <3E9F3D6F.9030501@pobox.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7BIT Disclaimer: Not speaking for Transmeta in any way, shape, or form. Copyright: Copyright 2003 H. Peter Anvin - All Rights Reserved Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Followup to: By author: Linus Torvalds In newsgroup: linux.dev.kernel > > > 2) why no sse2-optimized memcpy? just that noone has done one yet? > > Yes. If you want to, it's definitely the right thing to do. More so than > the 3dnow stuff that is by now ancient. HOWEVER, I don't think there are > any really valid large memcpy() calls inside the kernel. All the valid > ones are either special-cased (ie "copy_page()") or to user space. > It's questionable, though, if SSE-2 buys you anything SSE-1 doesn't already have. SSE-2 is basically integer and scalar ops for SSE, but data moving and even XOR is perfectly well handled by SSE-1. -hpa -- at work, in private! "Unix gives you enough rope to shoot yourself in the foot." Architectures needed: ia64 m68k mips64 ppc ppc64 s390 s390x sh v850 x86-64