[MPI3 Fortran] Deprecate mpif.h?

[Jeff Squyres]

Alexander:

1. You made up those numbers.  We cannot make decisions based on numbers that are totally fabricated.

2. Saying that the mpi3 module is only for Fortran 2008 compilers is incorrect.  IIRC, the Open MPI prototype implementation of "use mpi3" has been usable with the Intel Fortran compiler since v10.something, for example (it's up to v11.1.something these days).  

3. Painting a picture that only advanced / bleeding edge developers will be able to use mpi3 without major disruption is incorrect.  One of the reasons that the conversion functions exist is for exactly this purpose: you can extend legacy Fortran MPI applications with new MPI3 functionality.

4. Also, stating that you need to "use mpi3" globally throughout an application is incorrect.  As Bill pointed out earlier in this thread, in the scenario you raised, there's potentially only a small amount of new code that needs to use the mpi3 module.

Rolf raised some good technical points that need thought (e.g., datatype handling).  I'd much rather focus on facts and real issues rather than discuss fear, uncertainty, and doubt.  If you have marketing numbers and feedback from real Fortran MPI apps developers that show that deprecating mpif.h is a terrible idea, great -- let's see that data and discuss it.  So far, the feedback I have heard has been exactly opposite of what you're saying (e.g., talk to Torsten, who interfaces with many Fortran MPI app developers across several different fields).  Fabricating numbers based on your assumptions and then using those numbers as proof is not a good basis for discussion.

(I apologize for my frustration level)



On Mar 4, 2010, at 3:20 PM, Supalov, Alexander wrote:

> Thanks. Let us look into the following table:
> 
>                 MPI-2.2         MPI-3
> F77/mpif.h      85%                     5%
> 
> F90/mpi 5%                      2%
> 
> F2008/mpi3      2%                      1%
> 
> You appear to say that we have users in all cells: F77 diehards who don't care of the MPI news; ultra-modernists who will use F2008 and mpi3 module, and all hues in between. The numbers are just bogus representing how many people we may have in each "interest group" out of the total Fortran/MPI community. I did not put 99% into the upper left corner only to not reduce other cells to decimal fractions. :)
> 
> Now, imagine we deprecate the mpif.h/mpi module and add the mpi3 module. It look like we'll upset 90% of the users and prevent other 7% from going to MPI-3. Makes 97%. Bad.
> 
> Imagine we freeze mpif.h/mpi module and add mpi3 module. We'll probably hit 7% of the users who would otherwise be willing to try MPI-3. Not deadly but still painful.
> 
> Finally, imagine we do what was suggested earlier and do a reasonable job at maintaining mpif.h/mpi attractive to those in the more conservative upper part, and extending the mpi3 module as we please. I don't think we'll have anyone who gets to the street.
> 
> See what I mean? Now compare those numbers to the number of people in the MPI Forum. I would say that if there's pain in extending and maintaining the mpif.h/mpi module, we should probably bear it instead of making the user community suffer.
> 
> As they said once: "Never was so much owed by so many to so few". I'd love this to be said of us. What about you?
> 
> -----Original Message-----
> From: mpi3-fortran-bounces at lists.mpi-forum.org [mailto:mpi3-fortran-bounces at lists.mpi-forum.org] On Behalf Of N.M. Maclaren
> Sent: Thursday, March 04, 2010 8:27 PM
> To: MPI-3 Fortran working group
> Subject: Re: [MPI3 Fortran] Deprecate mpif.h?
> 
> On Mar 4 2010, Supalov, Alexander wrote:
> >
> >What is it that you doubt: the peace or the 99%?
> 
> Both.  As I said, there are quite a lot of people who want a cleaner
> interface but have no interest in the new features.  And there will
> always be some people who want every new gimmick but aren't prepared
> to change from coding in Fortran 77 - I was seeing people who were
> still coding in the Fortran 66 subset of Fortran 77 (with, very
> reluctantly, some use of CHARACTER) until quite recently!
> 
> So we won't get peace.
> 
> Regards,
> Nick Maclaren.
> 
> 
> 
> 
> 
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Jeff Squyres
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