ch_p4 / shmem on SMP linux cluster

[Frank Eisenmenger]

Hi,

trying to figure out, how to compile mpich-1.26 & mpiexec-0.77 on a 
Linux-cluster with a master node and 24 compute nodes connected by 
ethernet (all nodes: Dual Xeon processors, OS: Fedora Core). Both 
processors on each node share 2 GB of memory.

Compiled mpich '--with-comm=ch_p4'.
Therefore configured mpiexec with --disable-p4-shmem 
--with-default-comm=mpich-p4 & --with-smp-size=2.

mpiexec tests via ./runtests.pl worked fine.

Three questions:

Is this optimal to run jobs on 4, 8 .. processors, i.e. >= 2 nodes ?

Does it make sense to install an additional version of mpich/mpiexec 
with '--with-comm=shared' for running jobs on single nodes (i.e. on 2 
processors with shared memory) ?

May I compile ONE version of mpich with both types of comm., and select 
the appropriate one by using mpiexec's runtime options -mpich-p4-(no)shmem ?

Regards,
Frank.