From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S263584AbUAaJZL (ORCPT ); Sat, 31 Jan 2004 04:25:11 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S264286AbUAaJZK (ORCPT ); Sat, 31 Jan 2004 04:25:10 -0500 Received: from ns.suse.de ([195.135.220.2]:26539 "EHLO Cantor.suse.de") by vger.kernel.org with ESMTP id S263584AbUAaJZG (ORCPT ); Sat, 31 Jan 2004 04:25:06 -0500 Date: Sat, 31 Jan 2004 10:24:59 +0100 From: Andi Kleen To: "H. Peter Anvin" Cc: linux-kernel@vger.kernel.org, michael@mvdavid.com Subject: Re: raid6 badness Message-Id: <20040131102459.37b8929d.ak@suse.de> In-Reply-To: <401B421F.4060104@zytor.com> References: <401B421F.4060104@zytor.com> X-Mailer: Sylpheed version 0.9.7 (GTK+ 1.2.10; i686-pc-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 On Fri, 30 Jan 2004 21:50:23 -0800 "H. Peter Anvin" wrote: > Andi Kleen wrote: > > "H. Peter Anvin" writes: > > > >>I don't know what would cause the stack to be misaligned, however. > > > > x86-64 kernel doesn't guarantee the stack to be 16 byte aligned > > (although it usually is). If you need 16 byte alignment you have > > to align yourself. > > > > OK, that's unfortunate... per our discussion I really think this is a > bug, since the compiler still does 16-byte alignment, and thus we're > taking the cost without the benefit. I disagree on the "bug" part. I will check with the compiler guys, but as long as gcc doesn't rely on 16 byte alignment I will rather just disable it in the compiler. I don't see much sense in enforcing this just because of some obscure SSE2 function that can align itself. Saving instructions and stack space would be more important. -Andi