Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759130AbYHUQs1 (ORCPT ); Thu, 21 Aug 2008 12:48:27 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752332AbYHUQsT (ORCPT ); Thu, 21 Aug 2008 12:48:19 -0400 Received: from e35.co.us.ibm.com ([32.97.110.153]:53660 "EHLO e35.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751464AbYHUQsS (ORCPT ); Thu, 21 Aug 2008 12:48:18 -0400 Date: Thu, 21 Aug 2008 09:48:09 -0700 From: "Paul E. McKenney" To: Linus Torvalds Cc: Peter Zijlstra , Stefan Richter , jmerkey@wolfmountaingroup.com, linux-kernel@vger.kernel.org, Nick Piggin , David Howells Subject: Re: [ANNOUNCE] mdb: Merkey's Linux Kernel Debugger 2.6.27-rc4 released Message-ID: <20080821164809.GL6690@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com References: <200808210250.m7L2obNX028353@wolfmountaingroup.com> <1219313231.8651.101.camel@twins> <48AD4A0B.8020805@s5r6.in-berlin.de> <1219316568.8651.107.camel@twins> <20080821114745.GD21089@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.15+20070412 (2007-04-11) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1372 Lines: 33 On Thu, Aug 21, 2008 at 09:18:29AM -0700, Linus Torvalds wrote: > > > On Thu, 21 Aug 2008, Linus Torvalds wrote: > > > > No, I haven't seen the drafts > > Ok, I have looked at the draft now, and I don't think I was overly > pessimistic. > > If I read it right, all the memory ordering operations are defined for > _single_ objects. So if you want to do the kernel kind of memory ordering > where you specify ordering requirements independently of the actual > accesses (perhaps because the accesses are in some helper function that > doesn't care, but then you want to "finalize" the thing by stating a > sequence point), it seems to be impossible with current drafts. You are looking for atomic_fence() on page 1168 (1154 virtual) of the most recent draft. The current semantics are not correct, but this is being worked. And yes, it does currently have a variable associated with it, but it acts as a bare fence nevertheless. There is a proposal to drop the variable. As you said in a previous email, design by committee. > Oh, well. Nothing lost. I didn't expect the thing to work. ;-) Thanx, Paul -- 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/