From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755341AbXGUX1t (ORCPT ); Sat, 21 Jul 2007 19:27:49 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751946AbXGUX1l (ORCPT ); Sat, 21 Jul 2007 19:27:41 -0400 Received: from cantor.suse.de ([195.135.220.2]:36260 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751902AbXGUX1k (ORCPT ); Sat, 21 Jul 2007 19:27:40 -0400 From: Andi Kleen Organization: SUSE Linux Products GmbH, Nuernberg, GF: Markus Rex, HRB 16746 (AG Nuernberg) To: Oleg Verych Subject: Re: [PATCH] [9/58] x86_64: Always use builtin memcpy on gcc 4.3 Date: Sun, 22 Jul 2007 01:27:35 +0200 User-Agent: KMail/1.9.6 Cc: jh@suse.cz, patches@x86-64.org, linux-kernel@vger.kernel.org References: <200707191154.642492000@suse.de> <20070719095453.5434214E04@wotan.suse.de> In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-15" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200707220127.35975.ak@suse.de> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Sunday 22 July 2007 01:16:42 Oleg Verych wrote: > * From: Andi Kleen > * Date: Thu, 19 Jul 2007 11:54:53 +0200 (CEST) > > > > Jan asked to always use the builtin memcpy on gcc 4.3 mainline because > > it should generate better code than the old macro. Let's try it. > > Unfortunately such info is hard to find. The discuss@x86-64 list is > empty. So, let me ask how this memcpy relates to recently submitted > for glibc one [0]? It doesn't relate at all. The kernel still uses its own memcpy. Note that a lot of the traditional memcpy optimizations (like WC copies) are pointless in kernel space because the kernel rarely deals with continuous memory areas larger than a 4K page. The only difference from the patch is that instead of using an own heuristic when to use an out of line memcpy trust gcc's heuristic. -Andi