Calculation of worst-case execution time for multicore processors using deterministic execution

Abstract

Safety critical real time systems need to meet strict timing deadlines. We use a model checking based approach to calculate the WCET, where we apply optimizations to reduce the number of states stored by the model checker. Furthermore, we used deterministic shared memory accesses to further reduce calculation time, memory and number of states needed for calculating WCET. By optimizing the model checking code, we were able to complete benchmarks which otherwise were having state explosion problems. Furthermore, by using deterministic execution, we significantly reduced the calculation time (up to 158×), memory (up to 89×) and states needed (up to 188×) for calculating WCET with a negligible increase (up to 4%) in the calculated WCET for a multicore system with 4 cores. Lastly, unlike other state-of-the-art approaches, that perform binary search to search the WCET by running several iterations, our method calculates WCET in just one iteration. Taking all these optimizations into consideration, the gain in speed was from 1775× to 2471× for 4 threads.