Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751876AbWISRvf (ORCPT ); Tue, 19 Sep 2006 13:51:35 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751887AbWISRvf (ORCPT ); Tue, 19 Sep 2006 13:51:35 -0400 Received: from smtp102.mail.mud.yahoo.com ([209.191.85.212]:41374 "HELO smtp102.mail.mud.yahoo.com") by vger.kernel.org with SMTP id S1751876AbWISRve (ORCPT ); Tue, 19 Sep 2006 13:51:34 -0400 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.com.au; h=Received:Message-ID:Date:From:User-Agent:X-Accept-Language:MIME-Version:To:CC:Subject:References:In-Reply-To:Content-Type:Content-Transfer-Encoding; b=dEM+54IBkE1I7XI0jf0J7dPRCL3UMnb95HeyzQrs/X+MoQ9erbsE+/FNeyMQzQcSZMBAUc8LST+i31OVkolspJ8Z75vadmJO0qqEbNV/vDS6r+GiHuJHxPJ0LVp8lihH5Vc5g1QVGSfwYeZyUo7Opmsl+FvgEo++vBS8vppHk60= ; Message-ID: <45102E21.2060301@yahoo.com.au> Date: Wed, 20 Sep 2006 03:51:29 +1000 From: Nick Piggin User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7.12) Gecko/20051007 Debian/1.7.12-1 X-Accept-Language: en MIME-Version: 1.0 To: Alan Stern CC: "Paul E. McKenney" , David Howells , Kernel development list Subject: Re: Uses for memory barriers References: In-Reply-To: Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1005 Lines: 25 Alan Stern wrote: > On Wed, 20 Sep 2006, Nick Piggin wrote: >>I don't think that need be the case if one of the CPUs that has written >>the variable forwards the store to a subsequent load before it reaches >>the cache coherency (I could be wrong here). So if that is the case, then >>your above example would be correct. > > > I don't understand your comment. Are you saying it's possible for two > CPUs to observe the same two writes and see them occurring in opposite > orders? If store forwarding is able to occur outside cache coherency protocol, then I don't see why not. I would also be interested to know if this is the case on real systems. -- SUSE Labs, Novell Inc. Send instant messages to your online friends http://au.messenger.yahoo.com - 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/