A Variability-Aware Robust Design Space Exploration Methodology for On-Chip Multiprocessors Subject to Application-Specific Constraints

Manufacturing process variation is dramatically becoming one of the most important challenges related to power and performance optimization for sub-90nm CMOS technologies. Process variability impacts the optimization of the target system metrics, that is, performance and energy consumption by introducing fluctuations and unpredictability. Besides, it impacts the parametric yield of the chip with respect to application level constraints by reducing the number of devices working within normal operating conditions. The impact of variability on systems with stringent application-specific requirements (such as portable multimedia and critical embedded systems) is much greater than on general-purpose systems given the emphasis on predictability and reduced operating margins. In this market segment, failing to address such a problem within the early design stages of the chip may lead to missing market deadlines and suffering greater economic losses. In the context of a design space exploration framework for supporting the platform-based design approach, we address the problem of robustness with respect to manufacturing process variations. First, we apply Response Surface Modeling (RSM) techniques to enable an efficient evaluation of the statistical measures of execution time and energy consumption for each system configuration. Then, we apply a robust design space exploration framework to afford the problem of the impact of manufacturing process variations onto the system-level metrics and consequently onto the application-level constraints. We finally provide a comparison of our design space exploration technique with conventional approaches on two different case studies.