Parametric Approach to the Specification and Analysis of Real-time System Designs based on ACSR-VP

To engineer reliable real-time systems, it is desirable to discover timing anomalies early in the development process. However, there is little work addressing the problem of accurately predicting timing properties of real-time systems before implementations are developed. This paper describes an approach to the specification and analysis of scheduling problems of real-time systems. The method is based on ACSR-VP, which is an extension of ACSR, a real-time process algebra, with value-passing capabilities. Combined with the existing features of ACSR for representing time, synchronization and resource requirements, ACSR-VP can be used to describe an instance of a scheduling problem as a process that has parameters of the problem as free variables. The specification is analyzed by means of a symbolic algorithm. The outcome of the analysis is a set of equations and a solution to which yields the values of the parameters that make the system schedulable. These equations can be solved using integer programming or constraint logic programming. The paper presents the theory of ACSR-VP briefly and an example of the period assignment problem for rate-monotonic scheduling. We also explain our current tool implementation effort and plan for incorporating it into the existing toolset, PARAGON.