Ralph Castain <r...@open-mpi.org> writes: > You might also add the —display-allocation flag to mpirun so we can > see what it thinks the allocation looks like. If there are only 16 > slots on the node, it seems odd that OMPI would assign 32 procs to it > unless it thinks there is only 1 node in the job, and oversubscription > is allowed (which it won’t be by default if it read the GE allocation)
I think there's a problem with documentation at least not being explicit, and it would really help to have it clarified unless I'm missing some. Although there's probably more to it in this case, the behaviour seemed consistent with what I deduced (without reading the code) from the doc, ompi_info, and experiment that at least wasn't inconsistent: the node has 32 processing units, and the default allocation is by socket, apparently round-robin within nodes. I can't check the actual behaviour in that case just now.
