Subject: cc not sent before, oops

From: Tony Skjellum <[email-masked]>
Date: Mon, 28 Feb 94 11:14:50 CST

Subject: Clarifications of MPI_MAKE_CART
Content-Length: 1124

Rolf, hello.

We need to make the following clarification on MPI_MAKE_CART and
MPI_MAKE_GRAPH.  These functions are analogous to MPI_COMM_MAKE, except
that they also attach the topology capability to the output communicator.

The issue of caching semantics therefore arises.  I propose that caching
of attributes not be carried across by these functions, so they are
symmetric with MPI_COMM_MAKE, and that this be explicitly stated in the
text of section 6.5.

I consider this to be strictly an interpretation of what we have already
agreed upon, and invite your comments.  

-Tony

PS Can you remind me why we do not have a means to attach a topology to
an already existing communicator, which could be a non-communicating
collective operation?  This is mainly curiosity at this point.  I 
recognize that the functionality of MPI_MAKE_GRAPH/CART is superior
to that, but the functionality I mention is also without need of
communication, and analogous to adding other attributes to a communicator
(that is to say, user-defined topology functions could provide this
type of capability, so why not the MPI-defined approach?)