From owner-sc22wg5@open-std.org Thu Apr 22 17:53:29 2010 Return-Path: X-Original-To: sc22wg5-dom8 Delivered-To: sc22wg5-dom8@www2.open-std.org Received: by www2.open-std.org (Postfix, from userid 521) id 0E30CC3BA1F; Thu, 22 Apr 2010 17:53:29 +0200 (CET DST) X-Original-To: sc22wg5@open-std.org Delivered-To: sc22wg5@open-std.org Received: from ironport2.lbl.gov (ironport2.lbl.gov [128.3.41.14]) by www2.open-std.org (Postfix) with ESMTP id 25C38C178D9 for ; Thu, 22 Apr 2010 17:53:26 +0200 (CET DST) X-Ironport-SBRS: None X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: ApsEAH8N0EuAAwU8/2dsb2JhbACdGL9+AoJzghoEgzQ X-IronPort-AV: E=Sophos;i="4.52,257,1270450800"; d="scan'208";a="108962616" Received: from angilas.lbl.gov (HELO angilas.localnet) ([128.3.5.60]) by ironport2.lbl.gov with ESMTP/TLS/DHE-RSA-AES256-SHA; 22 Apr 2010 08:53:24 -0700 From: Aleksandar Donev Organization: LBL To: WG5 Subject: Re: (j3.2006) (SC22WG5.4258) [ukfortran] Question on locks Date: Thu, 22 Apr 2010 08:53:24 -0700 User-Agent: KMail/1.11.2 (Linux/2.6.28-17-generic; KDE/4.2.2; x86_64; ; ) References: <20100421204947.D8CC7C178DA@www2.open-std.org> <20100421221958.90A94C4E9FA@www2.open-std.org> <20100422073128.25D2DC178D9@www2.open-std.org> In-Reply-To: <20100422073128.25D2DC178D9@www2.open-std.org> MIME-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <201004220853.24260.adonev@lbl.gov> Sender: owner-sc22wg5@open-std.org Precedence: bulk On Thursday 22 April 2010, Reinhold Bader wrote: > (hopefully correctly) understand it is needed here since the > "user-defined way" described in NOTE 8.41 does not imply the one way > ordering enforced by the semantics of LOCK. There is no user-defined ordering without a sync memory. That is, user- defined ordering needs to order segments, and without a sync memory there is no segment boundary so there is nothing to order. Thus, you always need them for user-defined ordering. For built-in synchronizations, like SYNC ALL or LOCKs, the segments are delineated and ordered as specified in the standard. As to the "implicit sync memory" in some of the built ins, we had arguments about that (I wanted to remove that since I believe it is not necessary and does more harm than good...your question being to the point...but I lost or resigned to what is there in order to reach peace). My belief (maybe not shared by all on HPC subgroup) is that one never needs sync memories, explicit or implicit, with the built-in mechanisms. So you can simply forget about sync memory, as if it did not exist in the standard at all, *unless* you want to go beyond the built- in mechanisms. Best, Aleks -- Aleksandar Donev, Ph.D. Luis W. Alvarez Postdoctoral Fellow Center for Computational Sciences and Engineering (https://ccse.lbl.gov) Lawrence Berkeley National Laboratory (http://www.lbl.gov) E-mail: adonev@lbl.gov Phone: (510) 486-5782 Fax: (510) 486-6900 Address: MS 50A-1148, LBL, 1 Cyclotron Rd., Berkeley, CA 94720 Web: http://cims.nyu.edu/~donev/