[Mpi-22] determine if running in a heterogenous environment

[Dries Kimpe]

You have to draw the line somewhere ;-)

Especially since  -- assuming the user uses MPI_BYTE to describe
everything -- the MPI implementation cannot know if any of those datatypes
needing adjustment are used. Of course, the application could know this if
detailed information about the 

So, as soon as one of the predefined MPI datatypes is different I would
flag the peer (or communicator) as heterogen(e)ous.

For example, X86 vs X86_64 and gcc:
All C types, except for pointers and long integers are the same;
Still, I would say they are heterogen(e)ous without giving more details.

 Dries

* Jeff Squyres <jsquyres_at_[hidden]> [2008-03-03 13:24:11]:

> My point is that some datatypes may require translation while others  
> may not.  It's not always just endian differences -- sometimes there's  
> floating point representation differences, or size differences (e.g.,  
> sizeof(int) != sizeof(int)).







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