mpirun - not enough slots available

Question

Usually when I use mpirun, I can \"overload\" it, using more processors than there acctually are on my computer. For example, on my four-core mac, I can run mpirun -np

Answer 1

Apparently oversubscribing can be attained using the "--oversubscribe" option with mpirun - did the trick for me with running torque/maui

Answer 2

According to https://www.open-mpi.org/faq/?category=running#oversubscribing you could oversubscribe your node using a hostfile. Before proceeding, be careful that this way you can severely degrade the performance of the node. Also, if the system you use to run the application is using a queue system, this may not be valid.

First create a hostfile (named hostfile) containing

localhost slots=25

The simply run your application like

mpirun --hostfile hostfile -np 25 python -c "print 'hey'"