Unified methodology for resolving power-performance tradeoffs at the microarchitectural and circuit levels

Evaluation of architectural tradeoffs is complicated by implications in the circuit domain which are typically not captured in the analysis but substantially affect the results. We propose a metric of hardware intensity (η), which is useful for evaluating issues that affect both circuits and architecture. Analyzing data for actual designs we show how to measure the introduced parameters and discuss variations between observed results and common theoretical assumptions. For a power-efficient design we derive relations for η and supply voltage V under progressively more general situations, and incorporate η into a prior art architectural energy-efficiency criterion. Then, a more general relation is derived for the optimal balance between the architectural complexity, hardware intensity and power supply. Modified forms for these relations are obtained in special cases where the supply voltage is constrained or when clock gating is disallowed.