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Subject: Re: [OMPI users] OMPI 1.4.x ignores hostfile and launches all the processes on just one node in Grid Engine
From: Dave Love (d.love_at_[hidden])
Date: 2010-04-07 09:31:32

Serge <skhan_at_[hidden]> writes:

> However, there are cases when being able to specify the hostfile is
> important (hybrid jobs, users with MPICH jobs, etc.).

[I don't understand what MPICH has to do with it.]

> For example,
> with Grid Engine I can request four 4-core nodes, that is total of 16
> slots. But I also want to specify how to distribute processes on the
> nodes, so I create the file 'hosts'
> node01 slots=1
> node02 slots=1
> node03 slots=1
> node04 slots=1
> and modify the line in the submission script to:
> mpirun -hostfile hosts ./program

Regardless of any open-mpi bug, I'd have thought it was easier just to
use -npernode in that case. What's the problem with that? It seems to
me best generally to control the distribution of processes with mpirun
on the SGE-allocated nodes than to concoct host files as we used to do
here, e.g. to get -byslot v. -bynode behaviour (or vice versa).