Abstract:

This paper shows how thermal constraints affect the multidimensional design space for chip multiprocessors, considering the inter-related variables of CPU count, pipeline depth, superscalar width, L2 cache size, and operating voltage and frequency. The results show the importance of thermal modeling and the need for new thermal modeling capabilities and hence the need for collaboration between the thermal engineeringand computerarchitecturecommunities. Thermalconstraints both shift the optimal intra- and inter-core organization, and dominate other physical constraints such as pinbandwidth and power delivery. Different thermal constraints also require different optimization strategies. 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.