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Subject: [OMPI users] openmpi+torque: How run job in a subset of the allocation?
From: Ola.Widlund_at_[hidden]
Date: 2013-11-27 08:10:26


Hi,

We have an in-house application where we run two solvers in a loosely
coupled manner: The first solver runs a timestep, then the second solver
does work on the same timestep, etc. As the two solvers never execute at
the same time, we would like to run the two solvers in the same allocation
(launching mpirun once for each of them). RAM is not an issue, so there
should not be any risk of excessive swapping degrading performance.

We use openmpi-1.4.5 compiled with torque integration. The torque
integration means we do not give a hostfile to mpirun, it will itself
query torque for the allocation info.

Question:

Can we force one of the solvers to run in a *subset* of the full
allocation? How do we do that? I read in the FAQ that providing a hostfile
to mpirun in this case (when it's not needed due to torque integration)
would cause a lot of problems...

Thanks in advance,

Ola