[MPI3 Fortran] MPI Data types

Jeff Squyres jsquyres at cisco.com
Thu May 7 06:40:34 CDT 2009

On May 6, 2009, at 5:59 PM, Craig Rasmussen wrote:

> I'm not very familiar with creating and using MPI data types.  Does
> anyone foresee interoperability issues with MPI data types and  
> Fortran?

Creating and using MPI datatypes are mainly just describing to MPI  
what a "native" datatype looks like in memory.  One reason for this is  
that if you have non-contiguous data in memory, MPI can serialize it,  
send it across a network, and then lay it out in memory just like it  
was in the sender's memory (assuming the source and destination are  
the same type of platform, etc.).

So the word "datatype" here is a little confusing -- do not mix it up  
with language data types.  It's really just a memory layout  
description so that MPI can serialize / de-serialize data when  
transmitting / receiving across a network.

Jeff Squyres
Cisco Systems

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