foam-3.1 and openmpi 1.8.1
 

Hi,

I faced performance problem with system mpi (rhel6.6). A mpi version is 1.8.1 and latest source of the foam 3.1 is used. If on the same computer is running a one case everything works fine and performance is better than mpi 1.6.5. Performance dropping dramatically if I put other case to run by parallel. Looking at cpu load by "top" %CPU is only 50% and if the third case is put to running CPU load drop to 33.3%. So, from some reason cpus load is scaled by number of running task. This not happen by older mpi version.

Is it foam or mpi bug? or can it solve by some parameters?

Thanks

BR/Pekka