[mpich-discuss] Sorting nodes by CPUs with -ppn (1.4 and r9834)

[Yauheni Zelenko]

Hi!

Hydra assumes number of processes per node as number of cores (in 1.4 and r9834) when -ppn specified.

In this case -order-nodes behaves inconsistently with -ppn (order from command line) and without (nodes are sorted).

Our application could use mixed MPI/multi-threads mode. In this case with use -ppn 1, but still sorting nodes by number of CPUs make sense for us to run master process (rank 0) on host with most CPUs.

This is especially useful in farm environment like LSF/SGE/etc when CPUs on hosts may be allocated randomly.

Eugene.