From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S264388AbTDPObh (for ); Wed, 16 Apr 2003 10:31:37 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S264389AbTDPObh (for ); Wed, 16 Apr 2003 10:31:37 -0400 Received: from zero.aec.at ([193.170.194.10]:50948 "EHLO zero.aec.at") by vger.kernel.org with ESMTP id S264388AbTDPObg (for ); Wed, 16 Apr 2003 10:31:36 -0400 Date: Wed, 16 Apr 2003 16:43:12 +0200 From: Andi Kleen To: "David S. Miller" Cc: ak@muc.de, akpm@digeo.com, linux-kernel@vger.kernel.org, anton@samba.org, schwidefsky@de.ibm.com, davidm@hpl.hp.com, matthew@wil.cx, ralf@linux-mips.org, rth@redhat.com Subject: Re: Reduce struct page by 8 bytes on 64bit Message-ID: <20030416144312.GA2327@averell> References: <20030415112430.GA21072@averell> <20030416.054521.26525548.davem@redhat.com> <20030416140715.GA2159@averell> <20030416.072638.65480350.davem@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20030416.072638.65480350.davem@redhat.com> User-Agent: Mutt/1.4i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Apr 16, 2003 at 04:26:38PM +0200, David S. Miller wrote: > From: Andi Kleen > Date: Wed, 16 Apr 2003 16:07:15 +0200 > > How so? Of course I could write an generic set_bit32, but the question > is if these bit operations would be still atomic on SMP and not conflict with > fields occuping the same 8 byte slot. I remember you flaming someone > some time ago because he used set_bit in an atomic fashion on a type smaller > than unsigned long for example. > > It's OK if you align the pointer to 8 bytes, and subsequently the bit > offset as appropriate. :-) On sparc64. But is that true too for all other 64bit architectures supported? e.g. How about PA-RISC? (always seems to do things differently) -Andi