System-Level Modelling and Design Space Exploration for Multiprocessor Embedded System-on-Chip Architectures
Cagkan Erbas · Amsterdam University Press eBooks · 2006
Computational and communication events Application model Architecture model (programmable + dedicated HW) (only functional behavior) (b) The Artemis methodology separating application and architecture.CHAPTER 1 co-design, embedded systems design community has recently come up with a new design concept called system-level design, which incorporates ideas from the Ychart approach, as well as the following new notions:• Early exploration of the design space.In system-level design, designers start modeling and performance evaluation early in the design stage.Systemlevel models, which represent application behavior, architecture characteristics, and the relation between application and architecture (issues such as mapping, HW/SW partitioning), can provide initial estimations on the performance [78], [5], power consumption [89], or cost of the design [52].What is more, they do so at a high level of abstraction, and hence minimize the effort in model construction and foster fast system evaluation by achieving high simulation speeds.Figure 1.3 shows several abstraction levels that a system designer is likely to traverse in the way to the final implementation.After making some initial calculations, the designer proposes some candidate implementations.Each system-level implementation is then evaluated and compared at a high-level of abstraction one after another until a number of promising candidate implementations are identified.Because building these system-level models is relatively fast, the designer can repeat this process to cover a large design space.After this point, the designer further lowers the abstraction level, constructs cycle-accurate or synthesizable register transfer level (RTL) models, and hopefully reaches an optimal implementation with respect to his design criteria.This stepwise exploration of the design space requires an environment, in which there exist a number of models at different abstraction levels for the very same design.While the abstract executable models efficiently explore the large design space, more detailed models at the later stages convey more implementation details and subsequently attain better accuracy.• Platform architectures.Platform-based design [55] is gaining popularity due to high chip design and manufacturing costs together with increasing time-tomarket pressure.In this approach, a common platform architecture is specified and shared across multiple applications in a given application domain.This platform architecture ideally comes with a set of methods and tools which assists designers in the process of programming and evaluating such platform architectures.Briefly, platform-based design promotes the reuse of Intellectual Property (IP) blocks for the purpose of increasing productivity and reducing manufacturing costs by guaranteed high production volumes.• Separation of concerns.Separating various aspects of a design allows for more effective exploration of alternative implementations.One fundamental separation in the design process, which is proposed by the Y-chart approach, is the isolation of application (i.e.behavior, what the system is supposed to do) and architecture (how it does it) [4], [56].Another such separation is usually done between computation and communication.The latter, for example, can be realized at the application level by choosing an appropriate model of computation (MoC) for behavioral specification [64].For example,• presentation of a new software framework (Sesame) for modeling and simulating embedded systems architectures at multiple levels of abstraction.The Sesame software framework implements some widely accepted ideas proposed by the embedded systems community such as Y-chart based design and trace-driven co-simulation, as well as several new ideas like the gradual model refinement and high-level model calibration which are still in early stages of development.• derivation of an analytical model to capture early design decisions during the mapping stage in Sesame.The model takes into account three design objectives, and is solved to prune the large design space during the early