The current two-faced (or two-phase) proposal only permits *one* two
phase collective operation in a communicator at a time, so, as your
example hints, you have to dup the communicator twice to give you
three communicators if you need three concurrent two-faced operations.
It doesn't seem elegant, but I suppose it works.
-- Jim
James Cownie
Dolphin Interconnect Solutions
Phone : +44 117 9071438
E-Mail: jcownie@dolphinics.com