John,

To disable shared memory (sm or vader in Open MPI depending on the
version), you have to remove it from the list of approved underlying
network devices. As you specifically want TCP support, I would add "--mca
btl tcp,self" to my mpirun command line. However, by default Open MPI tries
to avoid using the loop back device to communication between processes on
the same node, so you will have to manually allow the loopback by adding
"--mca btl_tcp_if_include 127.0.0.1/24" to your command line.

More info can be found https://www.open-mpi.org/faq/?category=tcp

  George.



On Mon, Oct 30, 2017 at 1:18 PM, John Moore <johnpmoor...@gmail.com> wrote:

> I would like to test the network latency/bandwidth of each node that I am
> running on in parallel. I think the simplest way to do this would be to
> have each node test itself.
>
> My question is: How can I force all the OpenMPI TCP communication to go
> through the network adapter, and not use the optimized node-local
> communication?
>
> Any advice would be greatly appreciated.
>
> Best Regards,
> John
>
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