gpu - expore best mpi + mps configuration

[lastephey]

During the hackathon we saw speedups from using NVIDIA's MPS framework. We also saw some overhead we didn't fully understand.

Explore

• The best configuration of MPI + MPS ranks per frame (and per gpu)
• Single and multi-gpu strong scaling
• Single and multi-gpu weak scaling
• Overhead-- where it comes from and whether it is important

[lastephey]

Please document best configuration for 1 GPU, several GPUs, etc.

[lastephey]

Closing in the spirit of Closember.