Determining Actual Response Time in P-FRP

A purely functional model of computation, called Priority-based Functional Reactive Programming (P-FRP), has been introduced as a new paradigm for building real-time software. Unlike the classical preemptive model of real-time systems, preempted events in P-FRP are aborted and have to restart when higher priority events have completed, making the response time of events dependent on the execution pattern of higher priority events. Though methods to determine approximate values for the response time of P-FRP events have been presented, no convenient method has yet been established to determine actual response time. A common method for computing actual response time in the preemptive model does not give guaranteed results in P-FRP. A simulation based approach is computationally expensive and not feasible in most practical situations. We show that an exhaustive enumeration technique for idle periods is a more efficient technique, and can be easily adopted to determine actual response time in P-FRP.