From owner-sc22wg5+sc22wg5-dom8=www.open-std.org@open-std.org Thu Jul 6 12:45:47 2017 Return-Path: X-Original-To: sc22wg5-dom8 Delivered-To: sc22wg5-dom8@www.open-std.org Received: by www.open-std.org (Postfix, from userid 521) id 96C3535880C; Thu, 6 Jul 2017 12:45:47 +0200 (CEST) Delivered-To: sc22wg5@open-std.org X-Greylist: delayed 1380 seconds by postgrey-1.34 at www5.open-std.org; Thu, 06 Jul 2017 12:45:46 CEST Received: from ppsw-40.csi.cam.ac.uk (ppsw-40.csi.cam.ac.uk [131.111.8.140]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by www.open-std.org (Postfix) with ESMTP id 13030357250 for ; Thu, 6 Jul 2017 12:45:45 +0200 (CEST) X-Cam-AntiVirus: no malware found X-Cam-ScannerInfo: http://help.uis.cam.ac.uk/email-scanner-virus Received: from hermes-1.csi.cam.ac.uk ([131.111.8.51]:37266) by ppsw-40.csi.cam.ac.uk (smtp.hermes.cam.ac.uk [131.111.8.158]:25) with esmtpa (EXTERNAL:nmm1) id 1dT3vl-000EOv-lW (Exim 4.89) (return-path ); Thu, 06 Jul 2017 11:22:41 +0100 Received: from prayer by hermes-1.csi.cam.ac.uk (hermes.cam.ac.uk) with local (PRAYER:nmm1) id 1dT3vl-00066w-NA (Exim 4.89) (return-path ); Thu, 06 Jul 2017 11:22:41 +0100 Received: from [146.199.130.7] by old-webmail.hermes.cam.ac.uk with HTTP (Prayer-1.3.5); 06 Jul 2017 11:22:41 +0100 Date: 06 Jul 2017 11:22:41 +0100 From: "N.M. Maclaren" To: David Muxworthy Cc: sc22wg5@open-std.org Subject: Re: [ukfortran] (SC22WG5.5901) 3 levels of parallelism? Message-ID: In-Reply-To: <20170705221947.6DEEC3587D1@www.open-std.org> References: <20170705221947.6DEEC3587D1@www.open-std.org> X-Mailer: Prayer v1.3.5 Mime-Version: 1.0 Content-Type: text/plain; format=flowed; charset=ISO-8859-1 Sender: owner-sc22wg5@open-std.org Precedence: bulk OpenAcc has effectively been subsumed into OpenMP. Whether the OpenMP 'SIMD' features (i.e. OpenAcc) are practical is unclear, and the implementation status less so. My very limited feedback from people who have tried to use it was highly negative. As far as I know, CUDA looks likely to dominate for the forseeable future. Also, while languages are traditionally descriptive, not prescriptive, explicit threading (as in C++ etc.) and coarrays are both prescriptive models. In particular, they can't take advantage of SIMD, though Fortran as a whole can. Regards, Nick Maclaren.