Open Challenges for Probabilistic Measurement-Based Worst-Case Execution Time

The worst-case execution time (WCET) is a critical parameter describing the largest value for the execution time of programs. Even though such a parameter is very hard to attain, it is essential as part of guaranteeing a real-time system meets its timing requirements. The complexity of modern hardware has increased the challenges of statically analyzing the WCET and reduced the reliability of purely measuring the WCET. This has led to the emergence of probabilistic WCETs (pWCETs) analysis as a viable technique. The low probability of appearance of large execution times of a program has motivated the utilization of rare events theory like extreme value theory (EVT). As pWCET estimation based on EVT has matured as a discipline, a number of open challenges have become apparent when applying the existing approaches. This letter enumerates key challenges while establishing a state of the art of EVT-based pWCET estimation methods.