Re: 2-phase collective

James Cownie (jcownie@dolphinics.com)
Fri, 07 Feb 1997 09:38:45 +0000

Tony (and Nathan) said
> Nathan and I have been discussing this, and we will put our two cents
> into the pot:
>
> 1) Why not support all three modes?

but I don't understand what their proposal is.

Is it

1) 3 pairs of functions for each two faced collective

start_non_collective_foo
end_collective_foo

start_collective_foo
end_non_collective_foo

start_collective_foo
end_collective_foo

or

2) Simply stating (as was my suggestion) that both the start and end
functions are collective.

Remember that the definition of collective in MPI is only that the
call *may* require interaction with other processes, not that it
*must* require such interaction. Therefore stating that both the
start and end functions are collective allows any of the
implementations, and is really just a restriction on the user code,
forbidding things like

start_foo
send--------------->recv
start_foo

-- Jim

James Cownie
Dolphin Interconnect Solutions
Phone : +44 117 9071438
E-Mail: jcownie@dolphinics.com