kubernetes: controlling processes per node

[sheevy]

Is there a way of controlling a number of processes per node via an env variable? Similar to I_MPI_PERNODE in Intel's MPI version. Or can it only be done using -ppn command line parameter?

[hzhou]

Currently hydra only support setting ppn via command line. It is not difficult to add such env variable though. What is your use case that command line option is insufficient?

[hzhou]

Oh sorry, looks like hydra treats ppn the same way as openmpi if you omit -n.

[hzhou]

Just to establish the correct answer, if the host file is

host1:1
host2:4
host3:2

then mpirun command (omitting -n) will launch 7 processes according to the host file.

[alculquicondor]

if we omit -n, would hydra use all the hosts in the hostfile?

[hzhou]

Yes!

[alculquicondor]

oops, race-condition between the comments :)

Thanks for your help @hzhou.

I hope we can collaborate in the future if there are things we can do in mpich to support kubernetes better.