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Subject: [OMPI users] MPI doesn't recognize multiple cores available on multicore machines
From: Kyle Boe (boex0040_at_[hidden])
Date: 2012-04-24 17:52:15

I'm having a problem trying to use OpenMPI on some multicore machines I
have. The code I am running was giving me errors which suggested that MPI
was assigning multiple processes to the same core (which I do not want).
So, I tried launching my job using the -nooversubscribe option, and I get
this error:

bash-3.2$ mpirun -np 2 -nooversubscribe <executable and options here>
There are not enough slots available in the system to satisfy the 2 slots
that were requested by the application:
  <executable name>

Either request fewer slots for your application, or make more slots
for use.
A daemon (pid unknown) died unexpectedly on signal 1 while attempting to
launch so we are aborting.

There may be more information reported by the environment (see above).

This may be because the daemon was unable to find all the needed shared
libraries on the remote node. You may set your LD_LIBRARY_PATH to have the
location of the shared libraries on the remote nodes and this will
automatically be forwarded to the remote nodes.
mpirun noticed that the job aborted, but has no info as to the process
that caused that situation.
mpirun: clean termination accomplished

I am just trying to run on the localhost, not on any remote machines. This
happens on both my 8 (2*4) core and 24 (4*6) core machines. Relevant info:
I am not using any type of scheduler here, although from the searching I've
done that doesn't seem like a requirement. The only thing I can think is
there must be some type of configuration or option I'm not setting for
using on shared memory machines (either at compile or run time), but I
can't find anyone else who has come across this error. Any thoughts?