Systematic design space representation scheme for efficient exploration of ASIP

Abstract

Modern digital systems design requires extensive exploration on the large and complex design space to find the best or a set of satisfiable configurations which meet design requirements. However, the forms of all the possible designs are so diverse that any single description has not yet been devised to express them all. Instead of expressing all the architectural design space, previous work used only parameterization method for design space representation. This approach provides simple description on the design space. On the other hand, it has a limitation that it can not express architectural variation. This thesis proposes a sound semantics for design space representation, with which a designer can express the architectural variation as well as parameterization. We extended the classical AND/OR graph to hold the characteristics of design space of digital system. The main goal of the representation is two folds: representation in formal semantics and expressive power of design alternatives. To meet such a goal, a formalism of attributed AND-OR graph is defined for design space representation. The AND and OR relations in the graph can represent not only a collection of components (AND relation) to form a system but also variants of alternatives (OR relation) to be used for a given component. Moreover, attributes attached at the vertex can represent ranges of parameters and constraints on selection of a set of alternatives located at different sub-modules. Constraints can be a good means to reflect many designers`` knowledge base. Based on Attributed AND/OR Graph, complete design space exploration framework is exemplified by introducing plan-generation-evaluation framework. The plan process implies the construction of a complete design space. Generation is a phase to synthesize a complete simulation model and evaluation is a step to measure the performance index of the generated models. Attributed AND/OR graph is utilized to implement the plan process. In addit...