[MPICH] standardizing 64 bit integer MPI

[Karl Feind]

Greetings MPI standards enthusiasts:

Memory capacity on large computer systems and clusters conintues to increase.  
As the number of systems with substantially more memory than 2 GB per MPI 
process increases, the demand for a flavor of the MPI library to support MPI 
communication with message sizes or buffer sizes in excess of 2^31 elements
will also increase.   

The industry is pretty entrenched in a 32 bit default 
integer size for C "int" and Fortran INTEGER.   
See http://www.unix.org/whitepapers/64bit.html.

Perhaps the MPI Forum should consider adding 64 bit integer variants
of many of the MPI functions that specify "int" or "INTEGER" arguments
for the message size/count.  Eg.  MPI_Send and MPI_Recv.
I envision an interface called MPI_Send64 that specifies the "count"
argument is "int64" or "INTEGER(KIND=8)".

Do you agree there is a need?  Do you have any ideas about a solution for
this issue?

Thanks,
Karl Feind
SGI