Quincey Koziol wrote on Thu, 14 Oct 2010 at 20:44:23

On Oct 14, 2010, at 2:29 PM, Jeff Squyres wrote:

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On Oct 14, 2010, at 2:54 PM, Fab Tillier wrote:

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2. Add just the bare minimum, leverage datatypes to work around counts. Note that this requires introducing w versions of v collective APIs, to allow for different types (since the v functions allow different counts from each participant.)

This option also includes the "output" functions, right?

Yes, that's the basic idea.

BTW, I think this is a perfectly acceptable solution (as much as I'd like a blue pony :-). Fab was talking about just doing this, along with introducing MPI_Count, etc. for _future_ routines and getting a consensus from the forum that all future routines would use MPI_Count, etc. Since it only duplicates a few functions now (they necessary ones to get the I/O and datatype routines working with large counts), it satisfies a lot of "agile" design guidelines and I think it might be a very reasonable thing to do.

I don't know if the forum would go for defining new functions to use MPI_Count only. I think it's a brilliant idea personally, though one could make the argument that requiring something like MPI_IAlltoallv to take arrays of MPI_Count when taking arrays of int would be half the size would be detrimental to performance. -Fab