Benchmarking of communication techniques for GPUs

We report about the performances obtained, at the application level, by two MPI implementations for Infiniband that allow direct exchange of data stored in the global memory of Graphic Processing Units (GPU) based on the Nvidia CUDA. For the same purpose, we tested also the Application Programming Interface of APEnet, which is a custom, high performance interconnect technology. As a benchmark we consider the time required to update a single spin of the 3D Heisenberg spin glass model by using the over-relaxation algorithm. The results show that CUDA streams are instrumental in achieving the best possible performances.

► Perfect scaling is possible by using overlap between communication and computation.
► CUDA streams are crucial to achieve overlap between communication and computation.
► APEnet+ is a first example of interconnection technology that does not need a CPU.