Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1765309AbXHIULp (ORCPT ); Thu, 9 Aug 2007 16:11:45 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1764558AbXHIUKz (ORCPT ); Thu, 9 Aug 2007 16:10:55 -0400 Received: from zcars04f.nortel.com ([47.129.242.57]:45481 "EHLO zcars04f.nortel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932148AbXHIUKw (ORCPT ); Thu, 9 Aug 2007 16:10:52 -0400 Message-ID: <46BB74B9.4070702@nortel.com> Date: Thu, 09 Aug 2007 14:10:33 -0600 From: "Chris Friesen" User-Agent: Mozilla Thunderbird 1.0.2-6 (X11/20050513) X-Accept-Language: en-us, en MIME-Version: 1.0 To: Segher Boessenkool CC: Chris Snook , wjiang@resilience.com, wensong@linux-vs.org, heiko.carstens@de.ibm.com, linux-kernel@vger.kernel.org, ak@suse.de, netdev@vger.kernel.org, horms@verge.net.au, akpm@linux-foundation.org, linux-arch@vger.kernel.org, torvalds@linux-foundation.org, schwidefsky@de.ibm.com, davem@davemloft.net, zlynx@acm.org, rpjday@mindspring.com, jesper.juhl@gmail.com Subject: Re: [PATCH 24/24] document volatile atomic_read() behavior References: <20070809142430.GA19817@shell.boston.redhat.com> <8f6bb8a9e4f2819a161d732bdb6c70c0@kernel.crashing.org> <46BB403D.10202@redhat.com> <0a08872e608cf5f7a3d9c0fc746a1051@kernel.crashing.org> In-Reply-To: <0a08872e608cf5f7a3d9c0fc746a1051@kernel.crashing.org> Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit X-OriginalArrivalTime: 09 Aug 2007 20:10:39.0633 (UTC) FILETIME=[5B296010:01C7DAC1] Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 723 Lines: 19 Segher Boessenkool wrote: > Anyway, what's the supposed advantage of *(volatile *) vs. using > a real volatile object? That you can access that same object in > a non-volatile way? That's my understanding. That way accesses where you don't care about volatility may be optimised. For instance, in cases where there are already other things controlling visibility (as are needed for atomic increment, for example) you don't need to make the access itself volatile. Chris - 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/