A cross-layer approach for resiliency and energy efficiency in Near Threshold Computing

Energy constrained systems become the cornerstone of emerging energy harvested or battery-limited applications in Internet of Thing (IoT) platforms. A promising approach is to operate at near threshold voltage ranges, which can significantly reduce energy per operation. However, due to increased sensitivity to variations and reduced noise margin at low voltages, resiliency becomes a major challenge. In this paper we provide a cross layer approach, from compiler all the way to circuit design, to maximize the energy efficiency as well as the resiliency of functional units. The key idea is to identify the instructions which become timing critical at low voltages and address them by a combination of circuit redesign, multi-cycle execution and code replacement. This allows us to significantly reduce timing failures and at the same time limit leakage energy, which becomes considerable at low voltages. This approach enables resilient and energy efficient operation in a wide voltage range to trade off energy and performance.