An activity-sensitive contention delay model for highly efficient deterministic full-system simulations

As modern systems are integrating exceeding number of components for better performance and functionality, early full-system simulation tools have become essential for validating complex concurrent system interaction activities. In the past decades, many useful timing-accurate system simulation tools have been developed; however, we find that even for the most efficient techniques, more than 90% of overhead occurs when simulating shared devices, such as buses. Instead of adopting the constant-delay model that compromises accuracy or using the time-consuming precise scheduling approach, we propose in this paper an effective system activity-sensitive contention delay model that can dynamically capture runtime contention situations and system configuration changes. To verify the idea, we construct an analytical bus delay model and integrate that into a system simulation tool. The experimental results show 20 to 80 times performance improvement over the scheduling-based bus model on full-system simulations and the estimated timing difference is less than 3%.