From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753376AbXDMLpF (ORCPT ); Fri, 13 Apr 2007 07:45:05 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753411AbXDMLpF (ORCPT ); Fri, 13 Apr 2007 07:45:05 -0400 Received: from mx1.redhat.com ([66.187.233.31]:60674 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753376AbXDMLpD (ORCPT ); Fri, 13 Apr 2007 07:45:03 -0400 Organization: Red Hat UK Ltd. Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 3798903 Directors: Michael Cunningham (USA), Charlie Peters (USA) and David Owens (Ireland) From: David Howells In-Reply-To: <20070413102518.GD31487@wotan.suse.de> References: <20070413102518.GD31487@wotan.suse.de> <20070413100416.GC31487@wotan.suse.de> To: Nick Piggin Cc: Andrew Morton , Andi Kleen , Linux Kernel Mailing List , Linux Memory Management List , Linus Torvalds Subject: Re: [patch] generic rwsems X-Mailer: MH-E 8.0; nmh 1.1; GNU Emacs 22.0.50 Date: Fri, 13 Apr 2007 12:44:50 +0100 Message-ID: <25428.1176464690@redhat.com> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Nick Piggin wrote: > I think I should put wait_lock after wait_list, so as to get a better > packing on most 64-bit architectures. It makes no difference. struct lockdep_map contains at least one pointer and so is going to be 8-byte aligned (assuming it's there at all). struct rw_semaphore contains at least one pointer/long, so it will be padded out to 8-byte size. If you want to make a difference, you'd need to add __attribute__((packed)) but you would need to be very careful with that. David