A variation-tolerant scheduler for better than worst-case behavioral synthesis

Abstract

There has been a recent shift in design paradigms, with many turning towards yield-driven approaches to synthesize and design systems. A major cause of this shift is the continual scaling of transistors, making process variation impossible to ignore. Better than worst-case (BTW) designs also exploit these variation effects, while also addressing performance limits due to worst-case analysis. In this paper we first present the variation-tolerant stallable-FSM architecture, which provides fault detection and recovery, allowing circuits to be clocked at better than worst-case delays. Then we propose the BTW scheduler, a 0-1 integer linear programming (ILP) scheduling algorithm with the objective of minimizing the expected latency, to provide a high-level synthesis aid for the stallable-FSM architecture. We implemented the algorithm and ran it through many benchmarks, comparing the results with scheduling algorithms based on worst-case analysis. Our results were promising, showing up to 41% latency reduction for the BTW scheduler, and up to 43% latency reduction when combined with the variation-tolerant architecture.