NVIDIA HPC-X is a comprehensive software package that includes MPI and SHMEM communications libraries. HPC-X also includes various acceleration packages to improve both the performance and scalability of applications running on top of these libraries, including UCX (Unified Communication X), which accelerates the underlying send/receive (or put/get) messages. It also includes HCOLL, which accelerates the underlying collective operations used by the MPI/PGAS languages.