On Hybrid Abstraction-level Models in Architecture Simulation

In the life cycle of a hardware design, it is often needed to start first with a gross evaluation, typically performed using abstract simulation models, then refine the design in a step-wise approach towards more detailed and accurate evaluation. This progressive refinement process of the design may bring the system evaluation in a state where parts of the design are expressed in a high level of abstraction, while others are more detailed. This results in hybrid, or mixed-level, architecture simulation models. To support hybrid models, designers often apply intermediate components that translate transactions to a unique abstraction level. The process of translating from one abstraction level to another can have some side effects on the accuracy of the model being studied. The study presented in this paper, which has been conducted within the scope of the Artemis project, shows how dramatic the impact of the hybrid modeling can be on the accuracy of the system. The aim of this study is to point-out the impact of hybrid modeling when applied to very simple and common architecture models. The results show a number of interesting phenomena not expected beforehand. A detailed discussion of the simulation is presented as well as the first steps to solve the stated problems. Keywords—hybrid simulations, design space exploration, computer architecture simulation