mpiexec and mpich/p4 shared memory [was Re: [PBS-USERS] mpiexec with OpenPBS_2.3.16]

[Pete Wyckoff]

pw at osc.edu said:
> The mpiexec code is designed to use shared memory communication when you
> run more than one process on a node.  I could actually add an option to
> disable this, but I just assumed people would always want it.  I'll
> think about that and let you know if I make that work.

If you really do not want to recompile your mpich to add
--with-comm=shared, you can at least now configure mpiexec to
startup mpich/p4 codes without shared memory on SMP nodes.

Grab the latest from the cvs and configure as such:

    cvs -d :pserver:anoncvs at cvs.osc.edu:/cvs co mpiexec
    cd mpiexec
    ./configure --with-default-comm=p4 --disable-p4-shmem

I chose not to make it an mpiexec run-time option, although that would
be easy, since this is not something that users should turn on and off at
will.  It is absolutely imperative that mpich/p4 and mpiexec agree on
this shared memory setting.  The way jobs are started is quite different
in the two cases.

In other words, do one of the following scenarios but don't mix them:

    cd /usr/local/mpich
    ./configure --with-comm=shared ..
    cd /usr/local/mpiexec
    ./configure ..

or

    cd /usr/local/mpich
    ./configure ..
    cd /usr/local/mpiexec
    ./configure --disable-p4-shmem ..

I recommend that you try the first case if you can.

		-- Pete