Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757384AbXEMEjf (ORCPT ); Sun, 13 May 2007 00:39:35 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754297AbXEMEj1 (ORCPT ); Sun, 13 May 2007 00:39:27 -0400 Received: from extu-mxob-1.symantec.com ([216.10.194.28]:59296 "EHLO extu-mxob-1.symantec.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752403AbXEMEj0 (ORCPT ); Sun, 13 May 2007 00:39:26 -0400 Date: Sun, 13 May 2007 05:39:03 +0100 (BST) From: Hugh Dickins X-X-Sender: hugh@blonde.wat.veritas.com To: Nick Piggin cc: Benjamin Herrenschmidt , linux-arch@vger.kernel.org, Andrew Morton , Linux Kernel Mailing List , Linux Memory Management List Subject: Re: [rfc] optimise unlock_page In-Reply-To: <20070513033210.GA3667@wotan.suse.de> Message-ID: References: <20070508113709.GA19294@wotan.suse.de> <20070508114003.GB19294@wotan.suse.de> <1178659827.14928.85.camel@localhost.localdomain> <20070508224124.GD20174@wotan.suse.de> <20070508225012.GF20174@wotan.suse.de> <20070510033736.GA19196@wotan.suse.de> <20070511085424.GA15352@wotan.suse.de> <20070513033210.GA3667@wotan.suse.de> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-OriginalArrivalTime: 13 May 2007 04:39:24.0933 (UTC) FILETIME=[AEE4C350:01C79518] X-Brightmail-Verdict: VlJEQwAAAAIAAAABAAAAAAAAAAEAAAAAAAAABmluYm94AG5waWdnaW5Ac3VzZS5kZQBsaW51eC1hcmNoQHZnZXIua2VybmVsLm9yZwBsaW51eC1rZXJuZWxAdmdlci5rZXJuZWwub3JnAGFrcG1AbGludXgtZm91bmRhdGlvbi5vcmcAYmVuaEBrZXJuZWwuY3Jhc2hpbmcub3JnAGxpbnV4LW1tQGt2YWNrLm9yZwA= X-Brightmail-Tracker: AAAAAA== Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 867 Lines: 20 On Sun, 13 May 2007, Nick Piggin wrote: > On Fri, May 11, 2007 at 02:15:03PM +0100, Hugh Dickins wrote: > > > Hmm, well, I think that's fairly horrid, and would it even be > > guaranteed to work on all architectures? Playing with one char > > of an unsigned long in one way, while playing with the whole of > > the unsigned long in another way (bitops) sounds very dodgy to me. > > Of course not, but they can just use a regular atomic word sized > bitop. The problem with i386 is that its atomic ops also imply > memory barriers that you obviously don't need on unlock. But is it even a valid procedure on i386? Hugh - 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/