Variation-Aware Pipelined Cores through Path Shaping and Dynamic Cycle Adjustment

Ioannis Tsiokanos, Lev Mukhanov, Dimitrios S. Nikolopoulos, Georgios Karakonstantis
2018 Proceedings of the International Symposium on Low Power Electronics and Design - ISLPED '18  
In this paper, we propose a framework for minimizing variation-induced timing failures in pipelined designs, while limiting any overhead incurred by conventional guardband based schemes. Our approach initially limits the long latency paths (LLP s) and isolates them in as few pipeline stages as possible by shaping the path distribution. Such a strategy, facilitates the adoption of a special unit that predicts the excitation of the isolated LLP s and dynamically allows an extra cycle for the
more » ... etion of only these error-prone paths. Moreover, our framework performs post-layout dynamic timing analysis based on real operands that we extract from a variety of applications. This allows us to estimate the bit error rates under potential delay variations, while considering the dynamic data dependent path excitation. When applied to the implementation of an IEEE-754 compatible double precision floating-point unit (FPU) in a 45nm process technology, the path shaping helps to reduce the bit error rates on average by 2.71× compared to the reference design under 8% delay variations. The integrated LLP s prediction unit and the dynamic cycle adjustment avoid such failures and any quality loss at a cost of up-to 0.61% throughput and 0.3% area overheads, while saving 37.95% power on average compared to an FPU with pessimistic margins. CCS CONCEPTS Hardware → Arithmetic and datapath circuits; Very large scale integration design; Robustness; KEYWORDS Variation-aware FPU, error-resilience, path shaping, DTA
doi:10.1145/3218603.3218617 dblp:conf/islped/TsiokanosMNK18 fatcat:smwvykzuvnemtdxebyrifzp7ki