A model of a message-passing network is used to analyze the behavior of three implementations of the Chandy-Misra-Bryant parallel simulation algorithm. The characteristics of the model, the organization of the logical processes that constitute the simulator and the characteristics of the host parallel computer have a definite influence on the achieved performance, measured in terms of speedup. Large, loaded models help CMB to synchronize with a minimum overhead, efficiently exploiting the available parallelism. Mapping several LPs onto each processor achieves a better use of the available processing power, because while a LP is blocked (synchronizing) others can use the CPU. However, it is not convenient to map too many LPs onto each processor because the synchronization cost would be too high. The communication demands of CMB reduce its efficiency in environments where the cost of passing messages is too high: the performance of CMB running on a network of workstations is quite poor; in contrast, good speedups can be a.chieved using commercial multicomputers
