CONCURRENT CPU, GPU AND MIC EXECUTION ALGORITHMS FOR ARCHER MONTE CARLO CODE INVOLVING PHOTON AND NEUTRON RADIATION TRANSPORT PROBLEMS

摘要

ARCHER-CT and ARCHER-Neutron are Monte Carlo photon and neutron transport applications that have now been updated to utilize CPU, GPU and MIC computing devices concurrently. ARCHER detects and simultaneously utilizes all CPU, GPU and MIC processing devices that are available. A different device layout and load-balancing algorithm is implemented for each Monte Carlo transport application. ARCHER-CT utilizes a new "self service" approach that efficiently and effectively allows each device to independently grab portions of the domain and compute concurrently until the entire CT phantom domain has been simulated. ARCHER-Neutron uses a dynamic load-balancing algorithm that distributes the particles in each batch to each device based on its particles per second rate for the previous batch. This algorithm allows multiple architectures and devices to execute concurrently. A near linear scaling speedup is observed when using only GPU devices concurrently. New timing benchmarks using various combinations of various Intel and NVIDIA devices are made and presented for each application. A speedup of 16× for ARCHER-Neutron and 44× for ARCHER-CT has been observed when utilizing an entire 4U, 9 device heterogeneous computing system composed of an Intel CPU, an Intel MIC and 7 NVIDIA GPUs.