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My MPI application runs out of memory.
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The OpenMPI library sometimes consumes a lot of memory for its communication buffers. This seems to happen when an application does a lot of small send and receives. How to limit this?
You can limit the communication buffer counts and sizes using the mca parameters, this has helped for some applications that have experienced this problem.
For instance to limit the number of buffers used to 1000 you set this on the command line:
mpirun --mca btl_openib_free_list_max 1000 mpi-application.x
It is recommended to experiment with this to obtain optimal values, as setting it too low will decrease performance.
For more information about openmpi tunables see here.
