[MPI3 Fortran] MPI-2 Fortran question: 2D char array in MPI_COMM_SPAWN_MULTIPLE

Rolf Rabenseifner rabenseifner at hlrs.de
Thu May 27 05:09:27 CDT 2010


Whatever "icky" means, it is possible to write correct calls to
MPI_COMM_SPAWN and MPI_COMM_SPAWN_MULTIPLE and to correctly
catch the arguments by the MPI library routine.
Therefore, I would not spend additional work into this interface.
My opinion: it is not worth to spend to much effort in MPI Spawn.

Rolf

----- Original Message -----
> From: "Craig Rasmussen" <crasmussen at newmexicoconsortium.org>
> To: "MPI-3 Fortran working group" <mpi3-fortran at lists.mpi-forum.org>
> Sent: Wednesday, May 26, 2010 3:52:46 PM
> Subject: Re: [MPI3 Fortran] MPI-2 Fortran question: 2D char array in MPI_COMM_SPAWN_MULTIPLE

> Just to clarify.  Jeff and I believe the spec is "icky" (Jeff's words
> not mine :-)  ).  There may be ways to fix make it better in MPI-3.
>  I'll think about it and send out an email later to see if anyone has
> ideas on how to improve it.
> 
> 
> -craig
> 
> 
> On Tue, May 25, 2010 at 2:41 PM, Jeff Squyres < jsquyres at cisco.com >
> wrote:
> 
> 
> 
> On May 25, 2010, at 4:23 PM, Rolf Rabenseifner wrote:
> 
> > MPI-2.2, p310:18-25 defines:
> >
> > "The argv argument argv is an array of strings containing arguments
> > that are passed to
> > the program. The first element of argv is the first argument passed
> > to command, not, as
> > is conventional in some contexts, the command itself. The argument
> > list is terminated by
> > NULL in C and C++ and an empty string in Fortran.
> 
> I mis-read this last line when I read it -- now I understand what Rolf
> is saying (and, in fact, it's exactly what someone said earlier that
> the spec would need to be right).
> 
> Thanks Rolf!
> 
> 
> > The code fragment below is wrong because it does
> > try to detect an overall second_dim_size instead of individual
> > second_dim_size(i) for i=1,count.
> 
> Also a good point -- in OMPI, we assume that all the argv arrays will
> have the same number of tokens for each command.  But this is not
> necessarily the case.  I'll fix.
> 
> 
> 
> 
> Thanks!
> 
> -- Jeff Squyres
> jsquyres at cisco.com
> For corporate legal information go to:
> http://www.cisco.com/web/about/doing_business/legal/cri/
> 
> 
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-- 
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: Allmandring 30)




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