CMP design space exploration subject to physical constraints

Abstract

This paper explores the multi-dimensional design space for chip multiprocessors, exploring the inter-related variables of core count, pipeline depth, superscalar width, L2 cache size, and operating voltage and frequency, under various area and thermal constraints. The results show the importance of joint optimization. Thermal constraints dominate other physical constraints such as pin-bandwidth and power delivery, demonstrating the importance of considering thermal constraints while optimizing these other parameters. For aggressive cooling solutions, reducing power density is at least as important as reducing total power, while for low-cost cooling solutions, reducing total power is more important. Finally, the paper shows the challenges of accommodating both CPU-bound and memory-bound workloads on the same design. Their respective preferences for more cores and larger caches lead to increasingly irreconcilable configurations as area and other constraints are relaxed; rather than accommodating a happy medium, the extra resources simply encourage more extreme optimization points. © 2006 IEEE.