Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751194AbWCaDJn (ORCPT ); Thu, 30 Mar 2006 22:09:43 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751211AbWCaDJm (ORCPT ); Thu, 30 Mar 2006 22:09:42 -0500 Received: from mga01.intel.com ([192.55.52.88]:18331 "EHLO fmsmga101-1.fm.intel.com") by vger.kernel.org with ESMTP id S1751194AbWCaDJl (ORCPT ); Thu, 30 Mar 2006 22:09:41 -0500 X-IronPort-AV: i="4.03,148,1141632000"; d="scan'208"; a="18021274:sNHT16704569" Message-Id: <200603310309.k2V39dg28480@unix-os.sc.intel.com> From: "Chen, Kenneth W" To: "'Christoph Lameter'" Cc: "Nick Piggin" , "Zoltan Menyhart" , "Boehm, Hans" , "Grundler, Grant G" , , , Subject: RE: Synchronizing Bit operations V2 Date: Thu, 30 Mar 2006 19:10:24 -0800 MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit X-Mailer: Microsoft Office Outlook, Build 11.0.6353 Thread-Index: AcZUb3zYhAoOQy5mQEa/0BOcVokrBAAAGypw In-Reply-To: X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2180 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1018 Lines: 28 Christoph Lameter wrote on Thursday, March 30, 2006 7:02 PM > We are talking about IA64 and IA64 only generates an single instruction > with either release or acquire semantics for the case in which either > smb_mb__before/after_clear_bit does nothing. > > Neither acquire nor release is a memory barrier on IA64. The use of smp_mb__before_clear_bit(); clear_bit( ... ); is: all memory operations before this call will be visible before the clear_bit(). To me, that's release semantics. On ia64, we map the following: #define Smp_mb__before_clear_bit do { } while (0) #define clear_bit clear_bit_mode(..., RELEASE) Which looked perfect fine to me. I don't understand why you say it does not provide memory ordering. - Ken - 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/