Transient power management through high level synthesis

Abstract

The use of nanometer technologies is making it increasingly important to consider transient characteristics of a circuit's power dissipation (e.g., peak power, and power gradient or differential) in addition to its average power consumption. Current transient power analysis and reduction approaches are mostly at the transistor- and logic-levels. We argue that, as was the case with average power minimization, architectural solutions to transient power problems can complement and significantly extend the scope of lower-level techniques.In this work, we present a high-level synthesis approach to transient power management. We demonstrate how high-level synthesis can impact the cycle-by-cycle peak power and peak power differential for the synthesized implementation. Further, we demonstrate that it is necessary to consider transient power metrics judiciously in order to minimize or avoid area and performance overheads. In order to alleviate the limits on parallelism imposed by peak power constraints, we propose a novel technique based on the selective insertion of data monitor operations in the behavioral description. We present enhanced scheduling algorithms that can accept constraints on transient power characteristics (in addition to the conventional resource and performance constraints). Experimental results on several example designs obtained using a state-of-the-art commercial design flow and technology library indicate that high-level synthesis with transient power management results in significant benefits -- peak power reductions of up to 32% (average of 25%), and peak power differential reductions of up to 58% (average of 42%) -- with minimal performance overheads.