By using a macro/micro state model we show how assumptions on the resolution of logical and physical timing of computation in computer systems has resulted in design methodologies such as component-based decomposition, where they are completely coupled, and function/architecture separation, where they are completely independent. We discuss why these are inappropriate for emerging programmable, concurrent system design. By contrast, schedulers layered on hardware in concurrent systems already couple logical correctness with physical performance when they make effective resource sharing decisions. This paper lays a foundation for understanding how layered logical and physical sequencing will impact the design process, and provides insight into the problems that must be solved in such a design environment. Our layered approach is that of a virtual machine. We discuss our MESH research project in this context.
JoAnn M. Paul, Donald E. Thomas