The Optimal Quantum of Temporal Decoupling

Virtual Platforms (VPs) and Full System Simulators (FSSs) are among the fundamental tools of modern Multiprocessor System on A Chip (MPSoC) development. In the last two decades, the execution speed of these simulations did not grow at the same rate as the complexity of the systems to be simulated, creating a need for faster simulation techniques. A popular approach is temporal decoupling (TD), in which parts of the simulation are not synchronized with the rest of the system for a time called quantum. A high quantum is beneficial for simulation performance due to fewer synchronization/context switches. Yet, it also increases the probability of causality errors, leading to inaccuracies. Thus, most users of TD simulations face the question: Which quantum offers the optimal compromise between accuracy and performance? In practice and literature, the quantum is usually chosen based on empirical knowledge. This approach can achieve adequate performance/accuracy, but it lacks proper reasoning. In this work, we address this shortcoming by providing analytical estimations and deeper insights into the effects of Temporal Decoupling (TD). Additionally, we verify the proposed models using TD simulations in SystemC and gem5.