verifying SMP

[Ashley Pittman]

How do wildcard receives work in the multi-method case?  Do you have to
match the envelope using a common method, and then switch to another one
(shared memory in this case) to transfer the data or is there a better way
of doing this?

Ashley,

> What --with-comm=shared does for the ch_p4 device is add the 
> capability for
> messages to be transmitted through shared memory with memcpy 
> when the source
> and destination processes are on the same SMP (and TCP when 
> not).  Having to
> check both sources for incoming messages causes (instead of 
> just relying on
> select) introduces some overhead, and some find that their 
> applications do not
> perform much better than when they just use TCP for all 
> communication.  You
> will need to try it on your application to make sure.  Multi-method
> communication will be handled a little better in our new 
> implementation of
> MPICH.