Bounds and approximation for clocked interprocessor communication

The authors consider a clocked message transfer scheme in which message transfer is implemented as a periodic task with fixed overhead. Messages are then processed according to a priority discipline with preemption. Simple closed-form lower and upper bounds, and an approximation based on these bounds are found for the total system mean response time. Both bounds are tight for high processor occupancies, and simulation shows that the approximation is excellent for medium to high occupancies. Application to two different processors is given; the bounds and the approximation are found to be sufficiently tight, demonstrating the usefulness of this bounding and approximation technique for performance modelling of systems early in the design cycle.