Performance Characterization of Parallel Discrete Event Simulation on Knights Landing Processor

Performance and scalability of Parallel Discrete Event Simulation (PDES) is often limited by fine-grain communication, especially in execution environments with high communication cost. However, the low cost of on-chip communication in emerging many-core processors offers a promise to substantially alleviate conventional PDES bottlenecks. In this paper, we present a detailed evaluation and characterization of multi-threaded ROSS simulator on Intel's Knights Landing (KNL) processor. KNL is the second generation of the Intel Xeon Phi family of processors offering significant architecture improvements including 64 out-of-order multithreaded cores, sharing of some levels of the cache hierarchy among the cores, fast 2D mesh interconnect network and the ability to reconfigure the processor to support various clustering modes. We analyze the performance and scalability of ROSS simulator on KNL processor under different thread counts, communication patterns, event processing granularities, synchronization periods, thread placement policies, and workload partitioning schemes. We conclude that within a single KNL processor, up to 2X performance improvement can be achieved compared to commodity Xeon multicore processors. We show that in most cases the performance of ROSS scales well with the best results achieved when thread affinity is assigned, CPU cores are evenly loaded, cache sharing is exploited and communication is limited to small clusters of cores.