Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S263461AbTIWXp5 (ORCPT ); Tue, 23 Sep 2003 19:45:57 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S263453AbTIWXp5 (ORCPT ); Tue, 23 Sep 2003 19:45:57 -0400 Received: from pizda.ninka.net ([216.101.162.242]:3551 "EHLO pizda.ninka.net") by vger.kernel.org with ESMTP id S263397AbTIWXpy (ORCPT ); Tue, 23 Sep 2003 19:45:54 -0400 Date: Tue, 23 Sep 2003 16:32:52 -0700 From: "David S. Miller" To: "Luck, Tony" Cc: alan@lxorguk.ukuu.org.uk, davidm@hpl.hp.com, davidm@napali.hpl.hp.com, peter@chubb.wattle.id.au, bcrl@kvack.org, ak@suse.de, iod00d@hp.com, peterc@gelato.unsw.edu.au, linux-ns83820@kvack.org, linux-ia64@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: NS83820 2.6.0-test5 driver seems unstable on IA64 Message-Id: <20030923163252.2a93e406.davem@redhat.com> In-Reply-To: References: X-Mailer: Sylpheed version 0.9.2 (GTK+ 1.2.6; sparc-unknown-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1464 Lines: 34 On Tue, 23 Sep 2003 15:58:29 -0700 "Luck, Tony" wrote: > Which is great until the "cleverly written" program is fed a data set > that pushes into the unaligned case far more frequently than the > programmer anticipated. Which is why the people who work on the networking are well aware of the issues and will make sure the common case never triggers these unaligned accesses. People writing protocol stacks _don't_ feed these data unaligned cases out onto the wire, because like us they want the networking to go fast. Why in the world do you think they specify in the very RFCs that define the protocols that one should use NOP options in the TCP option area in order to align TCP timestamps on a 32-bit boundry? Do you think they say this so people can go ahead and use memmove()'s and byte loads all over the place anyways? No, rather, they specify things so that unless you do something absolutely stupid all the shit is aligned properly. It is absurdly stupid to do byte loads of TCP and IP header bits just because one tenth of one hundredths of one percent of systems have some configuration where word and half-word loads of these things will be unaligned _AND_ be slow on that cpu. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/