Cache-Related Timing Analysis for Multi-tasking Real-Time Systems with Nested Preemptions

In this paper, we propose an approach to estimate the Worst Case Response Time (WCRT) of each task in a preemptive multi-tasking single-processor real-time system utilizing an L1 cache. The approach combines inter-task cache eviction analysis and intra-task cache access analysis to estimate the number of cache lines that can possibly be evicted by the preempting task and also be accessed again by the preempted task after preemptions (thus requiring the preempted task to reload the cache line(s)). This cache reload delay caused by preempting task(s) is then incorporated into WCRT analysis. Two sets of applications are used to test our approach. Each set of applications contains three tasks. The experimental results show that our approach can tighten the WCRT estimate by up to 32% (1.4X) over prior state-of-the-art.