Period-dependent initial values for exact schedulability test of rate monotonic systems

Real-time systems using Rate Monotonic fixed priority scheduling can be checked for schedulability either by pessimistic schedulability conditions or exact testing. Exact testing provides a more precise result but cannot always be performed in polynomial time. Audsley et al. proposed one of the earliest methods by iteratively deriving the job response times. Other researchers have improved the efficiency of their exact test method by using different initial values. All currently proposed initial values do not use the relationship between task periods. In this paper we define initial values using the largest and the second largest periods in a system. We show that the new initial values can significantly improve the exact test.