From owner-sc22wg5+sc22wg5-dom8=www.open-std.org@open-std.org Tue Dec 10 00:05:18 2013 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 D343E3582EE; Tue, 10 Dec 2013 00:05:18 +0100 (CET) Delivered-To: sc22wg5@open-std.org Received: from mail.jpl.nasa.gov (smtp.jpl.nasa.gov [128.149.139.109]) by www.open-std.org (Postfix) with ESMTP id DEBCF3582C8 for ; Tue, 10 Dec 2013 00:05:16 +0100 (CET) Received: from [137.79.7.57] (math.jpl.nasa.gov [137.79.7.57]) by smtp.jpl.nasa.gov (Sentrion-MTA-4.3.1/Sentrion-MTA-4.3.1) with ESMTP id rB9N5DVk022820 (using TLSv1/SSLv3 with cipher DHE-RSA-AES256-SHA (256 bits) verified NO) for ; Mon, 9 Dec 2013 15:05:14 -0800 Subject: Re: (j3.2006) (SC22WG5.5124) image selectors From: Van Snyder Reply-To: Van.Snyder@jpl.nasa.gov To: sc22wg5 In-Reply-To: <52A39BE9.2060403@cray.com> References: <20131204000730.3A09F3582D0@www.open-std.org> <1386116202.16299.164.camel@math.jpl.nasa.gov> <52A39BE9.2060403@cray.com> Content-Type: text/plain; charset="ISO-8859-1" Organization: Yes Date: Mon, 09 Dec 2013 15:05:13 -0800 Message-ID: <1386630313.13428.23.camel@math.jpl.nasa.gov> Mime-Version: 1.0 X-Mailer: Evolution 2.32.3 (2.32.3-30.el6) Content-Transfer-Encoding: 7bit X-Source-Sender: Van.Snyder@jpl.nasa.gov X-AUTH: Authorized Sender: owner-sc22wg5@open-std.org Precedence: bulk On Sat, 2013-12-07 at 16:06 -0600, Bill Long wrote: > > On 12/3/13 6:16 PM, Van Snyder wrote: > > On Tue, 2013-12-03 at 18:02 -0600, Bill Long wrote: > >> The identification of the correct physical PE containing the coarray > >> being referenced using the new syntax involves two steps: Using the > >> specified cosubscripts and the current cobounds for the coarray, an > >> image index is computed. The image index is then converted to a > >> physical PE by a team-specific mapping. > > > > This is an important step that is not explained in the TS, or at least > > if it is, I couldn't find it. It needs to be in Subclause 5.1. > > > > OK. Reinhold's revised ballot reworded this idea in terms of the image > index in the initial team rather than physical processors. That is > arguably better terminology to use. The image's image index in the > initial team never changes throughout the program execution. I assume this refers to Reinhold's message of 2 December. That message's attachment did not include any comments concerning 5.1. The problem is that "image indices are relative to a specified team" at [9:5-6] does not give any information concerning the correspondence between coindices in parent teams and subteams, nor does "cosubscripts are interpreted as if the current team were the team specified by " at [11:4]. Without standardizing this, indexing with respect to ancestor teams is not useful. I tried in vain to find this mapping in 5.3 -- 5.5. The addition of DISTANCE to THIS_IMAGE doesn't seem to do the job. By the way, the edit for 13.7.165 at [33:7] needs "a" before "member". > I think a key point here is that the image is physically unchanged by > changing teams - it is still executing on the same processor/thread and > has all the same variables as before. What changes are the current > number of images and the current image index (i.e the values of > NUM_IMAGES() and THIS_IMAGE()). As side effects, the scope of > collective operations is (possibly) changed (if the number of images > changed), and the mapping from image index to physical processor > (probably) changed because the image index value (probably) changed but > the underlying processor/thread did not. > > Cheers, > Bill >