[Mpi-21] MPI-2.1: Fortran 90 bindings

[Jeff Squyres]

Good points; accepted as friendly amendments [to my as-yet nonexistent  
proposal :-) ].

On Mar 6, 2008, at 9:03 AM, Richard Treumann wrote:

> Jeff -
>
> The statement in the standard should allow an MPI implementation the  
> option of leaving out checking for MPI functions with single or  
> double CHOICE buffers but should not say they "are explicitly not  
> included in the F90 bindings.".
>
> It is possible that even 5,250 functions would be a problem on some  
> Fortran compilers and an implementation that has to deal with such a  
> compiler may wish to provide checking for the MPI subroutines that  
> do not have any CHOICE arguments but skip even the 5250 functions  
> for single CHOICE.
>
> Some Fortran compilers have non-standard features that allow a  
> formal parameter to be declared as what amounts to void* and with  
> that compile feature, CHOICE becomes easy. An MPI implementation  
> that is based on a Fortran compiler with this feature could check  
> even double CHOICE easily.
>
> Dick
>
> Dick Treumann - MPI Team/TCEM
> IBM Systems & Technology Group
> Dept 0lva / MS P963 -- 2455 South Road -- Poughkeepsie, NY 12601
> Tele (845) 433-7846 Fax (845) 433-8363
>
>
> mpi-21-bounces_at_[hidden] wrote on 03/05/2008 09:15:35 PM:
>
> > The current MPI-2 F90 bindings are un-implementable because they
> > require almost 7 *million* interface functions: with 15 intrinsic
> > Fortran types, each with 7 possible dimensions, the current F90
> > interface *requires*:
> >
> > - 50 MPI functions with one choice buffer: 15 * 7 * 50 = 5,250  
> functions
> > - 25 MPI functions with two choice buffers: (15 * 7 * 25)^2 = 6.8M
> > functions
> > - ...and a few hundred more MPI functions with no choice buffers
> >
> > This is clearly broken.
> >
> > An MPI-2.1-worthy solution could be to add a global statement saying
> > that MPI functions with two choice buffers are explicitly not  
> included
> > in the F90 bindings.  F90 MPI applications can transparently fall  
> back
> > to the F77 bindings (although they won't get the strong type  
> checking,
> > etc.).  This idea therefore fits the requirement of not breaking any
> > existing MPI codes.
> >
> > Specifically: if we remove the requirement to provide all MPI
> > functions with two choice buffers, 5,000+ F90 interface functions is
> > [a pain but] implementable.  I doubt that any current MPI
> > implementation provides more than the no-choice-buffers plus one-
> > choice-buffer functions anyway...
> >
> > If this seems like a good idea, I can write a proper proposal for  
> it.
> > Comments?
> >
> > --
> > Jeff Squyres
> > Cisco Systems
> >
> > _______________________________________________
> > mpi-21 mailing list
> > mpi-21_at_[hidden]
> > http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi-21
> _______________________________________________
> mpi-21 mailing list
> mpi-21_at_[hidden]
> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi-21


-- 
Jeff Squyres
Cisco Systems