[MPIWG Fortran] Type of MPI_Status

Mon Mar 17 11:52:37 CDT 2014

Jeff and I had a similar conversation last week.  It is my viewpoint that the MPI-3 interfaces are formal interfaces that can be adapted by an implementation in a way that formally meets the specification.

For Open MPI I believe that Jeff will add configuration magic to check is INTEGER(C_INT) and default INTEGER have the same KIND value.  This should be true for 100% of the compilers.  If not, then that compiler will not be able to build Open MPI.

The use of INTEGER(C_INT) to replace the default INTEGER in the MPI types is needed to stopped compiler warning from GNU.  We did this work (adding BIND(C) to gfortran) at Los Alamos and I think we perhaps got carried away with the warning messages.

Craig Rasmussen
CAS Scientific Programmer
rasmus at cas.uoregon.edu

On Mar 14, 2014, at 4:11 PM, Junchao Zhang wrote:

> Not sure if it is worth discussing.  Even if INTEGER and C_INT are of different size, I think I can still use C_INT in MPI_Status.
> 
>     TYPE, BIND(C) :: MPI_Status
>         INTEGER(C_INT) :: MPI_SOURCE, MPI_TAG, MPI_ERROR
>         ... ! other fields
>     END TYPE MPI_Status
> 
> Since MPI_Status is a derived datatype, users access it through its public interfaces(i.e., %MPI_SOURCE, ..., MPI_STATUS_SIZE). 
> As long as MPI_STATUS_SIZE >= sizeof(MPI_STATUS)/sizeof(INTEGER), who cares its internals.
> 
> 
> --Junchao Zhang
> 
> 
> On Thu, Mar 13, 2014 at 10:56 AM, Rolf Rabenseifner <rabenseifner at hlrs.de> wrote:
> Jeff is right.
> Bill's theoretical statement is also correct.
> 
> And ticket#415 is also correct because it resolves an inconsistency
> within the mpi_f08 interface.
> 
> Strange theoretical discussions are also there for
> long Fortran INTEGER may not be identical with some shorter INTEGER(C_int).
> As a side effect also solved by this ticket.
> 
> Rolf
> 
> ----- Original Message -----
> > From: "Jeff Hammond" <jeff.science at gmail.com>
> > To: "MPI-WG Fortran working group" mpi-forum.org>
> > Sent: Thursday, March 13, 2014 4:12:56 PM
> > Subject: Re: [MPIWG Fortran] Type of MPI_Status
> >
> > MPI should test for interoperability of Fortran's default integer and
> > light the machine room on fire if it is not.
> >
> > Jeff
> >
> > On Thu, Mar 13, 2014 at 8:58 AM, Bill Long <longb at cray.com> wrote:
> > > This does raise an earlier issue that it is
> > > possible that Fortran’s default INTEGER is not an interoperable
> > > type, and thus the MPI_Status type should not be a BIND(C) type if
> > > it has INTEGER components.  Having BIND(C) does allow you to
> > > declare a C global name MPI_STATUS_IGNORE in Fortran, which solves
> > > one problem nicely.  I don’t see any advantage to having INTEGER
> > > components (as opposed to INTEGER(C_Int), for example). So this
> > > seems to represent the worse of the two options.
> > >
> > > Cheers,
> > > Bill
> > >
> > >
> > >
> > > On Mar 13, 2014, at 8:36 AM, Jeff Squyres (jsquyres)
> > > <jsquyres at cisco.com> wrote:
> > >
> > >> Done.  Good catch:
> > >>
> > >>    https://svn.mpi-forum.org/trac/mpi-forum-web/ticket/415
> > >>
> > >> This is a trivial ticket, but if you could make sure it's ok, I'll
> > >> send it to the mpi-forum list so that it can get added to the
> > >> next meeting's agenda.
> > >>
> > >>
> > >> On Mar 13, 2014, at 1:51 AM, Rolf Rabenseifner
> > >> <rabenseifner at hlrs.de> wrote:
> > >>
> > >>> Jeff and Junchao,
> > >>>
> > >>> it is a missing word INTEGER in this part of the sentence
> > >>>
> > >>> In whole MPI these three values are in Fortran INTEGER and
> > >>> nothing else
> > >>>
> > >>> Junchao, thank you for the hint that an erratum is neede
> > >>>        to prevent from such misinterpretation
> > >>>
> > >>> Jeff, please can you file the errata ticket resulting in
> > >>>
> > >>>   ... containing three public INTEGER fields named ...
> > >>>
> > >>> Best regards
> > >>> Rolf
> > >>>
> > >>>
> > >>> ----- Original Message -----
> > >>>> From: "Junchao Zhang" <jczhang at mcs.anl.gov>
> > >>>> To: "MPI-WG Fortran working group"
> > >>>> mpi-forum.org>
> > >>>> Sent: Thursday, March 13, 2014 4:49:49 AM
> > >>>> Subject: [MPIWG Fortran] Type of MPI_Status
> > >>>>
> > >>>>
> > >>>>
> > >>>>
> > >>>> Hello,
> > >>>>
> > >>>>
> > >>>> p30 of MPI3 says "In Fortran with USE mpi or INCLUDE ’mpif.h’,
> > >>>> status
> > >>>> is an array of INTEGERs of size MPI_STATUS_SIZE. ..., With
> > >>>> Fortran
> > >>>> USE mpi_f08, status is defined as the Fortran BIND(C) derived
> > >>>> type
> > >>>> TYPE(MPI_Status) containing three public fields named MPI_SOURCE
> > >>>> ,
> > >>>> MPI_TAG , and MPI_ERROR"
> > >>>>
> > >>>> In other words, it does't say type of the three public fields
> > >>>> must be
> > >>>> INTEGER. So, in mpi_f08, can I declare MPI_Status as
> > >>>>
> > >>>>
> > >>>> TYPE, BIND(C) :: MPI_Status
> > >>>> INTEGER(C_INT) :: MPI_SOURCE, MPI_TAG, MPI_ERROR
> > >>>> ... ! other fields
> > >>>> END TYPE MPI_Status
> > >>>>
> > >>>>
> > >>>> I find it makes MPI_Status binding easier. Since this type is
> > >>>> interoperable with C, I do not need to allocate temp variables
> > >>>> to do
> > >>>> type conversion when INTEGER is not a C_INT.
> > >>>>
> > >>>>
> > >>>>
> > >>>> --Junchao Zhang
> > >>>> _______________________________________________
> > >>>> mpiwg-fortran mailing list
> > >>>> mpiwg-fortran at lists.mpi-forum.org
> > >>>> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpiwg-fortran
> > >>>
> > >>> --
> > >>> Dr. Rolf Rabenseifner . . . . . . . . . .. email
> > >>> rabenseifner at hlrs.de
> > >>> High Performance Computing Center (HLRS) . phone
> > >>> ++49(0)711/685-65530
> > >>> University of Stuttgart . . . . . . . . .. fax ++49(0)711 /
> > >>> 685-65832
> > >>> Head of Dpmt Parallel Computing . . .
> > >>> www.hlrs.de/people/rabenseifner
> > >>> Nobelstr. 19, D-70550 Stuttgart, Germany . . . . (Office: Room
> > >>> 1.307)
> > >>> _______________________________________________
> > >>> mpiwg-fortran mailing list
> > >>> mpiwg-fortran at lists.mpi-forum.org
> > >>> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpiwg-fortran
> > >>
> > >>
> > >> --
> > >> Jeff Squyres
> > >> jsquyres at cisco.com
> > >> For corporate legal information go to:
> > >> http://www.cisco.com/web/about/doing_business/legal/cri/
> > >>
> > >> _______________________________________________
> > >> mpiwg-fortran mailing list
> > >> mpiwg-fortran at lists.mpi-forum.org
> > >> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpiwg-fortran
> > >
> > > Bill Long
> > >                                                                       longb at cray.com
> > > Fortran Technical Suport  &                                  voice:
> > >  651-605-9024
> > > Bioinformatics Software Development                     fax:
> > >  651-605-9142
> > > Cray Inc./ Cray Plaza, Suite 210/ 380 Jackson St./ St. Paul, MN
> > > 55101
> > >
> > >
> > > _______________________________________________
> > > mpiwg-fortran mailing list
> > > mpiwg-fortran at lists.mpi-forum.org
> > > http://lists.mpi-forum.org/mailman/listinfo.cgi/mpiwg-fortran
> >
> >
> >
> > --
> > Jeff Hammond
> > jeff.science at gmail.com
> > _______________________________________________
> > mpiwg-fortran mailing list
> > mpiwg-fortran at lists.mpi-forum.org
> > http://lists.mpi-forum.org/mailman/listinfo.cgi/mpiwg-fortran
> 
> --
> Dr. Rolf Rabenseifner . . . . . . . . . .. email rabenseifner at hlrs.de
> High Performance Computing Center (HLRS) . phone ++49(0)711/685-65530
> University of Stuttgart . . . . . . . . .. fax ++49(0)711 / 685-65832
> Head of Dpmt Parallel Computing . . . www.hlrs.de/people/rabenseifner
> Nobelstr. 19, D-70550 Stuttgart, Germany . . . . (Office: Room 1.307)
> _______________________________________________
> mpiwg-fortran mailing list
> mpiwg-fortran at lists.mpi-forum.org
> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpiwg-fortran
> 
> _______________________________________________
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> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpiwg-fortran

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