Benefits of Optimistic Parallel Discrete Event Simulation for Network-on-Chip Simulation

The end of Moore's law has placed a two-fold demand on hardware simulation. Firstly, efficient co-design requires fast simulation of hardware systems in order to vet proposed designs. Secondly, modern simulator platforms need to become increasingly concurrent as well. To address these challenges, we develop an optimistic time warp-based parallelization for the Structural Simulation Toolkit (SST). Our optimistic PDES engine hides synchronization costs by speculatively executing tasks, leading to better compute resource utilization on modern multicore architectures. Given the significant engineering effort to make custom existing hardware models reversible, we also develop a new SST component, called escher. The escher workflow instruments arbitrary SST applications and replays event traces through the different SST parallelizations. This is a useful tool for hardware engineers who want to understand the benefits of optimistic parallelization before undertaking the significant software engineering effort to make their hardware models reversible. We demonstrate this workflow by generating traces for a tiled mesh-NOC architecture and show a 2.1x to 3.7x speed-up using our optimistic SST parallelization versus the current conservative SST parallelization.