From owner-sc22wg5@open-std.org Thu Oct 22 07:45:51 2009 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 4DB3BC76BB7; Thu, 22 Oct 2009 07:45:51 +0200 (CET DST) X-Original-To: sc22wg5@open-std.org Delivered-To: sc22wg5@open-std.org X-Greylist: delayed 344 seconds by postgrey-1.18 at www2.open-std.org; Thu, 22 Oct 2009 07:45:50 CET DST Received: from n16a.bullet.mail.mud.yahoo.com (n16a.bullet.mail.mud.yahoo.com [68.142.207.126]) by www2.open-std.org (Postfix) with SMTP id 25BDCC178E4 for ; Thu, 22 Oct 2009 07:45:49 +0200 (CET DST) Received: from [68.142.200.221] by n16.bullet.mail.mud.yahoo.com with NNFMP; 22 Oct 2009 05:40:04 -0000 Received: from [68.142.201.243] by t9.bullet.mud.yahoo.com with NNFMP; 22 Oct 2009 05:40:04 -0000 Received: from [127.0.0.1] by omp404.mail.mud.yahoo.com with NNFMP; 22 Oct 2009 05:40:04 -0000 X-Yahoo-Newman-Id: 24731.54608.bm@omp404.mail.mud.yahoo.com Received: (qmail 71222 invoked from network); 22 Oct 2009 05:40:03 -0000 Received: from adsl-76-238-155-24.dsl.lsan03.sbcglobal.net (van.snyder@76.238.155.24 with plain) by smtp107.sbc.mail.sp1.yahoo.com with SMTP; 21 Oct 2009 22:40:03 -0700 PDT X-Yahoo-SMTP: EsWMRgGswBCJ115Lh3i7tuoFc7oZg_W1NL_P8LouqQe9CakaKQ-- X-YMail-OSG: QyQ0K0kVM1lQV4bDsocXRVFydqKZkydwl5NwxibKQBG0ZJ0GMXGd6oN1eyOXzUF7epgVMjABwupY4Ro7jT9Tz5tC3WzmRkGTMXkjQ9ZO6X6Do3B1IBNW14RiXSM_rf0I6DB4wMwwCdXkbIzisAGjo50BUjF_gkB_1jTb6Pul_5g0iKH8fXYBP7FwsCLgfoTB_KXUBU0wO2gReqD5qBw81JjpSZRsXJIrsCXDKEi_E_eH9W4g8Afg24orPm2byuOr X-Yahoo-Newman-Property: ymail-3 Message-ID: <4ADFEEEA.4000002@jpl.nasa.gov> Date: Wed, 21 Oct 2009 22:34:34 -0700 From: Van Snyder Reply-To: van.snyder@jpl.nasa.gov User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.8.1.6) Gecko/20070802 SeaMonkey/1.1.4 MIME-Version: 1.0 To: WG5 Subject: Re: (j3.2006) (SC22WG5.4105) [ukfortran] Standard intrinsics and coarrays References: <20091020111544.C0F5CC178E3@www2.open-std.org><20091020154252.946EAC178E3@www2.open-std.org><20091021161933.1B2FCC178E3@www2.open-std.org><20091021171501.21FA4C178E3@www2.open-std.org><20091021175702.E4D26C178E3@www2.open-std.org> <20091022043326.83DB9C178E4@www2.open-std.org> <20091022051613.0AEF5C178E4@www2.open-std.org> In-Reply-To: <20091022051613.0AEF5C178E4@www2.open-std.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-sc22wg5@open-std.org Precedence: bulk Malcolm Cohen wrote: > Aleksandar Donev wrote: > >> It is processor dependent whether all images use a common >> generator or whether each image uses a separate one. >> > > Perhaps we should require that it should be one or the other. > If we require a single generator, it's difficult to get the same sequence on a particular image on consecutive runs, which is useful (some would say indispensible) for debogging, without specifying rigorous synchronization, which might be more rigorous than the problem needs. If we require separate generators, one can get the effect of a single generator by having one image do the generation. This might entail an inolerable performance penalty. It looks like Hobson's choice, but we ought either to choose, to provide a mechanism for a program to choose, or require the processor to provide a mechanism, outside the language, to choose. -- Van