(j3.2006) [MPI3 Fortran] Feedback from Fortran J3 meeting

[Robert Corbett]

Bill Long wrote:
> 
> Keith Bierman wrote:
> 
>>On May 28, 2008, at 10:56 AM   5/28/, Craig Rasmussen wrote:
>>
>>  
>>
>>>I wonder how C does this?  What are the rules for code motion in C?
>>>I'll ask around.
>>>
>>>    
>>
>>Highly prescribed by their Standard. Fortran's advantage has been  
>>much more latitude to the optimizer.
>>
>>While the Committee has always preferred to design more generic  
>>solutions, MPI is an important special case ... it might just be a  
>>lot easier to have an optional part of the Standard which puts MPI in  
>>as special modules ...
> 
> 
> I see this as very backward looking.  We've done a lot of work to 
> produce a native parallel programming model within Fortran that lacks 
> these problems that MPI has.  Producing a whole optional part of the 
> standard just to accommodate a legacy library that one would expect, 
> over time, to fall by the wayside, seems like a bad idea on multiple fronts.

I very much doubt that Coarray Fortran will ever overtake MPI in usage.
Failure to support MPI in Fortran might drive those MPI users away from
using Fortran.

> If vendors are currently getting it "wrong", how is it possible that so 
> many people are using MPI today?  I'm yet to be convinced there is a 
> real problem.

MPI works very well at low optimization levels.

Bob Corbett