Set OpenMPI MCA parameters

OpenMPI MCA parameters can be set in several ways. Some MCA parameters configure hardware, while other configure warnings. Depending on whether the parameters need to be per-user, per-hardware, etc. it may be useful to set some in a file, and others in the environment variables, and still others on the command line.

OpenMPI looks for a file at ~/.openmpi/mca-params.conf to set MCA parameters. The environment variables have a higher priority, and the command line has the highest priority as is intuitive.

The mca-params.conf syntax is like:

btl_openib_warn_no_device_params_found = 0

The environment variables would be set in ~/.profile like:

export UCX_TLS=ud,sm,self