From owner-sc22wg5@open-std.org Wed Nov 5 23:56:53 2008 Return-Path: X-Original-To: sc22wg5-dom7 Delivered-To: sc22wg5-dom7@www2.open-std.org Received: by www2.open-std.org (Postfix, from userid 521) id B697ACA3434; Wed, 5 Nov 2008 23:56:53 +0100 (CET) X-Original-To: sc22wg5@open-std.org Delivered-To: sc22wg5@open-std.org Received: from ppsw-0.csi.cam.ac.uk (ppsw-0.csi.cam.ac.uk [131.111.8.130]) by www2.open-std.org (Postfix) with ESMTP id 022E3CA3428 for ; Wed, 5 Nov 2008 23:56:52 +0100 (CET) X-Cam-AntiVirus: no malware found X-Cam-SpamDetails: not scanned X-Cam-ScannerInfo: http://www.cam.ac.uk/cs/email/scanner/ Received: from hermes-1.csi.cam.ac.uk ([131.111.8.51]:52549) by ppsw-0.csi.cam.ac.uk (smtp.hermes.cam.ac.uk [131.111.8.150]:25) with esmtpa (EXTERNAL:nmm1) id 1KxrIx-00023I-2b (Exim 4.70) for sc22wg5@open-std.org (return-path ); Wed, 05 Nov 2008 22:56:51 +0000 Received: from prayer by hermes-1.csi.cam.ac.uk (hermes.cam.ac.uk) with local (PRAYER:nmm1) id 1KxrIx-0008Sa-Pi (Exim 4.67) for sc22wg5@open-std.org (return-path ); Wed, 05 Nov 2008 22:56:51 +0000 Received: from [83.67.89.123] by webmail.hermes.cam.ac.uk with HTTP (Prayer-1.3.1); 05 Nov 2008 22:56:51 +0000 Date: 05 Nov 2008 22:56:51 +0000 From: "N.M. Maclaren" To: sc22wg5 Subject: Re: [ukfortran] (SC22WG5.3621) A comment on John Wallin's comments on Nick MacLaren's comments Message-ID: X-Mailer: Prayer v1.3.1 Mime-Version: 1.0 Content-Type: text/plain; format=flowed; charset=ISO-8859-1 Sender: owner-sc22wg5@open-std.org Precedence: bulk On Nov 5 2008, Van Snyder wrote: > >I remarked on this problem before m185, and proposed a trivial addition >to the OPEN statement to allow message passing using I/O statements, >which already know how to do DTIO and asynchronous, in 08-204. Subgroup >didn't even consider it. > >If coarrays are kicked off the train in Tokyo, we really should go back >and look at the directions proposed in 08-204 and 08-205. Fortran I/O >applied to message passing should provide all the basic functionality of >MPI, and would be far clearer. Er, no. They would provide the point-to-point functionality, but that is not quite the same. In my MPI course, I teach collectives as the basic functionality, and point-to-point as the specialist feature! However, I am not saying that internal FIFOs aren't a good communication mechanism - far from it - merely that MPI is more than that. >Within a single SMP, say a dual quad-core PC, one can already accomplish >what's proposed in 08-204 with a pipe, but I haven't met a system yet >where pipes work across NFS. 08-204 provides syntax for users to hook >to stuff that vendors provide that go beyond NFS. 08-205 provides a way >for users to roll their own, perhaps atop MPI, while hiding the ugly >details behind I/O statements. I am not quite sure what you mean. The basic FIFO aspect of pipes is preserved across NFS - if you are referring to multiple sources or multiple sinks, that is going a bit beyond pipes. And, of course, there is nothing stated about when data is transferred - but that is true even of local pipes. What definitely is the case is that the metadata and contents can get out of of sync in NFS version 3, even in the simplest configurations. But a pure pipe doesn't rely on stat(). Regards, Nick Maclaren, University of Cambridge Computing Service, New Museums Site, Pembroke Street, Cambridge CB2 3QH, England. Email: nmm1@cam.ac.uk Tel.: +44 1223 334761 Fax: +44 1223 334679