Micro-Synchronization in Conservative Parallel Network Simulation

Lookahead is a critical factor in conservative parallel simulation. Greater lookahead usually brings better performance. However, in the simulation of computer networks, lookahead is usually determined by the minimal delay of the border links between any two subnets that simulated by different sequential logical processes (LPs), which is too small to get good performance. Traditionally, the lookahead exploitation usually only reflects the parallelism among LPs, which possibly wastes the potential parallelism inside each LP, especially, in the case that each LP simulates thousands of entities. Here we present a simple method called micro-synchronization to exploit the parallelism inside each LP. Different from the previous work, such as lookahead accumulation and local time warp, we keep the traditional usage of lookahead among LPs unchanged, and however, we impose the relaxed sequential event scheduling inside each LP, which can indirectly improve the lookahead. We also present a state causality model to prove the correctness of our method, which means that there is no risk in the relaxed sequential execution. Finally, the experiment evaluates our method and shows that it can improve the performance of conservative parallel simulation of computer networks to some extent.