An FPTAS for Interface Selection in the Periodic Resource Model∗

The periodic resource model of Shin and Lee [18] provides a flexible, simple framework for designing compositional real-time systems. Each component in the periodic resource model has an interface which specifies the period and capacity of the resource used to schedule the component. Unfortunately, the best-known exact algorithms for determining the interface parameters for a components in the periodic resource model potentially require exponential or pseudo-polynomial time. In this paper, we obtain an FPTAS for the problem of selecting an interface period given a capacity-determination algorithm. We also apply our approach to obtain an FPTAS for the problem of selecting both a period and capacity for components consisting of sporadic task systems. Our algorithms obtain interface parameters with interface bandwidth at most (1 + ) times the optimal for any > 0.