Debugging Time Behavior of Probabilistic Real-time Systems

In order to detect bugs in the temporal behavior of real-time systems (i.e., discrepancies between the theoretical and the actual behavior), measurements of the running system can be taken. These measurements must then be compared with the specifications and the model used to analyze the feasibility of the system. This comparison, which is straightforward when a deterministic model is used, becomes more difficult when probabilistic constraints and models are used. In this paper we discuss this problem and explore some solutions. We propose two heuristic metrics, optimism and pessimism, and show, by means of a case study, how they help in finding bugs.