From owner-sc22wg5@open-std.org Thu Jan 22 23:18:41 2009 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 0CB47CA5FED; Thu, 22 Jan 2009 23:18:41 +0100 (CET) X-Original-To: sc22wg5@open-std.org Delivered-To: sc22wg5@open-std.org Received: from e2.ny.us.ibm.com (e2.ny.us.ibm.com [32.97.182.142]) by www2.open-std.org (Postfix) with ESMTP id 55565CA5FE6 for ; Thu, 22 Jan 2009 23:18:39 +0100 (CET) Received: from d01relay02.pok.ibm.com (d01relay02.pok.ibm.com [9.56.227.234]) by e2.ny.us.ibm.com (8.13.1/8.13.1) with ESMTP id n0MMH3Ll010003 for ; Thu, 22 Jan 2009 17:17:03 -0500 Received: from d01av04.pok.ibm.com (d01av04.pok.ibm.com [9.56.224.64]) by d01relay02.pok.ibm.com (8.13.8/8.13.8/NCO v9.1) with ESMTP id n0MMIcH5190138 for ; Thu, 22 Jan 2009 17:18:38 -0500 Received: from d01av04.pok.ibm.com (loopback [127.0.0.1]) by d01av04.pok.ibm.com (8.12.11.20060308/8.13.3) with ESMTP id n0MMIbNi031456 for ; Thu, 22 Jan 2009 17:18:38 -0500 Received: from d25ml04.torolab.ibm.com (d25ml04.torolab.ibm.com [9.26.6.105]) by d01av04.pok.ibm.com (8.12.11.20060308/8.12.11) with ESMTP id n0MMIbYk031427; Thu, 22 Jan 2009 17:18:37 -0500 In-Reply-To: <20090122214202.3AB89CA5FE6@www2.open-std.org> References: <20090122100652.C31E9CA3434@www2.open-std.org> <4978A8A0.8090407@cray.com> <20090122175730.8BA1BCA3439@www2.open-std.org> <4978C20F.2070207@cray.com> <20090122214202.3AB89CA5FE6@www2.open-std.org> To: Van.Snyder@jpl.nasa.gov Cc: WG5 MIME-Version: 1.0 Subject: Re: (j3.2006) (SC22WG5.3903) [MPI3 Fortran] [ukfortran] [MPI3 Fortran] MPI non-blocking transfers X-Mailer: Lotus Notes Release 8.0.1 HF105 April 10, 2008 Message-ID: From: Jim Xia Date: Thu, 22 Jan 2009 17:19:13 -0500 X-MIMETrack: Serialize by Router on D25ML04/25/M/IBM(Release 7.0.3FP1|February 24, 2008) at 01/22/2009 17:19:14, Serialize complete at 01/22/2009 17:19:14 Content-Type: multipart/alternative; boundary="=_alternative 007A8D4B85257546_=" Sender: owner-sc22wg5@open-std.org Precedence: bulk This is a multipart message in MIME format. --=_alternative 007A8D4B85257546_= Content-Type: text/plain; charset="US-ASCII" From: Van Snyder To: "longb@cray.com" , fortran standards email list for J3 Cc: WG5 , "mpi3-fortran@lists.mpi-forum.org" Date: 01/22/2009 04:45 PM Subject: (j3.2006) (SC22WG5.3903) [MPI3 Fortran] [ukfortran] [MPI3 Fortran] MPI non-blocking transfers On Thu, 2009-01-22 at 10:59 -0800, Bill Long wrote: > When we're talking about a Fortran's asynchronous > attribute, it seems reasonable to relate it to Fortran's concept of > I/O. When a Fortran program invokes an external procedure with an actual argument that has the ASYNCHRONOUS attribute, and all you have for the external procedure is a .o file, how does the compiler know whether the procedure does Fortran I/O, or something else? Sad to say, but true to some compiler writers: asynchronous alone will have no impact on how the procedure call is dealt with (or optimized). Asynchronous attribute will only take effect when there is a corresponding WAIT statement somewhere due to the "invisible hands" referred to by Bill. I think asynchronous approach to nonblocking transfer may lead to nowhere, at least not as easy as it appears. Cheers Jim Xia RL Fortran Compiler Test IBM Toronto Lab at 8200 Warden Ave, Markham, On, L6G 1C7 Phone (905) 413-3444 Tie-line 313-3444 email: jimxia@ca.ibm.com D2/YF7/8200 /MKM --=_alternative 007A8D4B85257546_= Content-Type: text/html; charset="US-ASCII"


From: Van Snyder <Van.Snyder@jpl.nasa.gov>
To: "longb@cray.com" <longb@cray.com>, fortran standards email list for J3 <j3@j3-fortran.org>
Cc: WG5 <sc22wg5@open-std.org>, "mpi3-fortran@lists.mpi-forum.org" <mpi3-fortran@lists.mpi-forum.org>
Date: 01/22/2009 04:45 PM
Subject: (j3.2006) (SC22WG5.3903) [MPI3 Fortran] [ukfortran] [MPI3        Fortran]        MPI non-blocking transfers





On Thu, 2009-01-22 at 10:59 -0800, Bill Long wrote:
> When we're talking about a Fortran's asynchronous
> attribute, it seems reasonable to relate it to Fortran's concept of
> I/O.

When a Fortran program invokes an external procedure with an actual
argument that has the ASYNCHRONOUS attribute, and all you have for the
external procedure is a .o file, how does the compiler know whether the
procedure does Fortran I/O, or something else?
Sad to say, but true to some compiler writers: asynchronous alone will have no impact on how the procedure call is dealt with (or optimized).  Asynchronous attribute will only take effect when there is a corresponding WAIT statement somewhere due to the "invisible hands" referred to by Bill.  I think asynchronous approach to nonblocking transfer may lead to nowhere, at least not as easy as it appears.

Cheers


Jim Xia

RL Fortran Compiler Test
IBM Toronto Lab at 8200 Warden Ave, Markham, On, L6G 1C7
Phone (905) 413-3444  Tie-line 313-3444
email: jimxia@ca.ibm.com
D2/YF7/8200 /MKM --=_alternative 007A8D4B85257546_=--