On Mar 1, 2005, at 9:24 AM, Maharaja Pandian wrote:
> I would like to find out about the default selection of rpi and coll
> modules.
>
> My understanding is that if nothing is selected at run time, as a
> default,
> the usysv rpi module will be chosen for point-to-point communication
> because usysv has the highest default priority of 40.
Correct.
> And, smp/shmem coll module will be chosen for collective communication
> because both have priority 50.
It's not quite as simple as priority for the coll modules.
shmem will only assert a priority of 50 if all the processes in a
communicator are on the same node. Otherwise, it won't allow itself to
be selected at all.
Similarly, smp will only assert a priority of 50 if the communicator
spans more than one node and at least one of the nodes has multiple
processes in the communicator. Otherwise, it won't allow itself to be
used at all.
If neither of these are met, then basic will be used.
--
{+} Jeff Squyres
{+} jsquyres_at_[hidden]
{+} http://www.lam-mpi.org/
|
