Static Probabilistic Timing Analysis in Presence of Faults

Accurate timing prediction for software execution is becoming a problem due to the increasing complexity of computer architecture, and the presence of mixed-criticality workloads. Probabilistic caches were proposed to set bounds to Worst Case Execution Time (WCET) estimates and help designers improve system resource usage. However, as technology scales down, system fault rates increase and timing behavior is affected. In this paper, we propose a Static Probabilistic Timing Analysis (SPTA) approach for caches with evict-on-miss random replacement policy using a state space modeling technique, with consideration of fault impacts on both timing analysis and task WCET. Different scenarios of transient and permanent faults are investigated. Results show that our proposed approach provides tight probabilistic WCET (pWCET) estimates and as fault rate increases, the timing behavior of the system can be affected significantly.