I am trying to follow this tutorial for building and running an MPI application on an ARM based Ubuntu 11.10 system.
When installing open-mpi environment on my PC machine, the sample program runs well. However, trying the same on the ARM machine, the terminal hangs up and I need to kill the MPI process from a second terminal in order to release it.
The MPI packages I installed using apt-get, on both machines, were mpi-default-dev and mpi-default-bin, so I assume that the packages are as updated as they can be.
The first sample program in the tutorial makes every process prints a “hello” message with some info. On the PC I get messages from all 8 processes (although running on a single core) and then the program ends. On the ARM, I get no output at all. The program is just stuck immediately after launch.
Any idea on what’s wrong? I am not sure even where to start to debug this?
Update: I tried removing the OpenMPI package and install the alternative MPICH2 package – but the result is just the same.
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Answer
Ubuntu 11.10 did not ship with a functional Open MPI implementation for ARM (although it may have shipped with a nonfunctional one). Ubuntu 12.04 did.
I would recommend building your own Open MPI from source – available at http://www.open-mpi.org/software/ompi/v1.6/, unless you can update to a more recent version of Ubuntu.
Alternatively, you could rebuild the 11.10 package using the fixes pointed out in https://bugs.launchpad.net/ubuntu/+source/openmpi/+bug/949044.