On Dec 4, 2007, at 10:11 AM, Ralph H Castain wrote:
> (a) do we want to retain the feature to run non-MPI jobs with mpirun
> (and accept the tradeoffs, including the one described below in II)?
> (b) do we provide a flag to mpirun (perhaps adding the distinction
> "orterun" must be used for non-MPI jobs?) to indicate "this is NOT
> an MPI
> job" so we can act accordingly?
Based on talking to Ralph this morning, I'd [cautiously] be in favor
of b) -- have an MCA param / command line switch that allows switching
between jobs that call orte_init and those that do not, along with
setting the default by looking at argv (orterun = does not call
orte_init, mpirun = does call orte_init).
The benefits are what Ralph described: less complex ORTE code and the
potential for optimizations that are difficult if you don't know if
the launched applications are going to call MPI_INIT (orte_init) or not.
But this is definitely a change from past behavior -- so it's worth
community discussion. The real question is: how many OMPI users
actually use mpirun to launch non-MPI jobs?
My $0.02 is that we're focusing ORTE on OMPI these days. So
optimizing more for MPI starting is a Good Thing(tm).
> (c) simply eliminate support for non-MPI jobs?
> (d) other suggestions?