[MPI3 Fortran] Deprecate mpif.h?

Thu Mar 4 15:09:43 CST 2010

Yes, I presume there will be some people like this.

Let me differentiate who we're talking about. There are developers/architects who will normally do anything to improve the program. I guess you may be referring to them. Now, there are also QA and PV people who will shoot any of that down on sight. Then there are ISO, CMMI, security, etc. cert people who will check boxes and not let anything out until all boxes are checked. Then there are project leads who listen to all those and from above. And finally there are managers who basically pay for all this.

As soon as anyone tells the latter they can't keep the schedule, it's the developers who get squeezed, and they know this. So, apart from the natural variation in character and mood, the developers will try to do as little as possible to get as much out as they will be allowed to. This is the sort of people who falls into the target group that may want "mpif.h/F77, NB collectives, and also _that_ thing". I think we should determine what "_that_ thing" they will want, and put it into the mpif.h/mpi module alongside the NB collectives.

That is, if the mpi3 module must be backward incompatible with the mpif.h/mpi module. Because if it won't, we'll have no problem to solve. [Running for cover.]

-----Original Message-----
From: mpi3-fortran-bounces at lists.mpi-forum.org [mailto:mpi3-fortran-bounces at lists.mpi-forum.org] On Behalf Of Bill Long
Sent: Thursday, March 04, 2010 9:43 PM
To: MPI-3 Fortran working group
Subject: Re: [MPI3 Fortran] Deprecate mpif.h?

I guess I'm missing something here.   Are you saying that there is a 
large group of people who are willing to change their codes to include 
(or replace current calls to blocking routines with) calls to NB 
communication routines, but for some reason refuse to make one other 
change, i.e. to replace the 'include "mpif.h" line with a USE mpi3 
statement?    Are the consequences of that extra edit really so 
horrible?  It does assume they have access to a 'modern' compiler, but 
that compiler will still accept their old statements. They don't have to 
rewrite the rest of their code.  They don't even have to know it is a 
'modern' compiler - vendors typically supply only one actual compiler 
anyway.

Cheers,
Bill

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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-- 
Bill Long                                           longb at cray.com
Fortran Technical Support    &                 voice: 651-605-9024
Bioinformatics Software Development            fax:   651-605-9142
Cray Inc./Cray Plaza, Suite 210/380 Jackson St./St. Paul, MN 55101

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