Design Automation and Architecture Design for Near Threshold Computing

物联网（IoT）是一个快速增长的市场，对工业和个人生活的各个方面产生重大影响。物联网边缘设备严重依赖于超低功耗和减小的外形尺寸。在各种使用场景中，许多物联网设备可以收集能量或使用有限的电池工作，并且预计将运行很长的使用寿命。他们还需要适应动态能源，并调整性能，准确性和正确性，以满足严格的能源预算。在这种情况下，通过将电源电压降低到晶体管的阈值电压的近阈值计算（NTC）是显著降低能耗的有前途的方法。然而，在NTC电路、结构和系统设计中存在各种挑战，这需要全新的分析框架、电子设计自动化（EDA）工具和设计范例。特别是，降低电源电压是以显著的弹性损失为代价的，这是由于更高的故障率和对变化的更高的敏感性。因此，节能弹性是在NTC运行的IoT边缘设备的主要挑战。该提案的主要前提是为近阈值计算系统开发跨层可靠的设计自动化和架构设计方法，这些方法推动了物联网中许多新兴的应用领域。弹性NTC电路和架构的正确设计是通过一系列跨层技术实现的，从电路，逻辑设计和自动化流程一直到NTC的系统架构。我们特别提出开发i）逻辑和存储器优化以在近阈值状态下操作可靠性，ii）运行时调整和适应以预测和减轻由于近阈值操作引起的故障，以及iii）通过近似计算在近阈值计算中包含残余误差。

Internet of Things (IoT) is a fast growing market with significant impacts in various aspects of industry and personal life. IoT edge devices critically depend on ultra-low power and reduced form-factor. Many IoT devices in various usage scenarios could be energy-harvested or work with limited battery, and expected to run for a long operational lifetime. They also require to adapt for energy on-the-fly, and adjust performance, accuracy, and correctness to meet the stringent energy budget. In this context, near threshold computing (NTC), by lowering the supply voltage down to the threshold voltage of transistors, is a promising approach to significantly reduce energy consumption. However, there are various challenges in NTC circuit, architecture and system design, which require completely new analysis frameworks, electronic design automation (EDA) tools, and design paradigms. In particular, reducing the supply voltage comes at the expense of significant resiliency loss, due to higher failure rates and increased sensitivity to variations. Therefore, energy-efficient resiliency is a major challenge for IoT edge devices operating at NTC. The main premise of this proposal is to develop cross-layer reliable design automation and architecture design methodologies for near threshold computing systems, which drive many emerging application domains in IoT. Proper design of resilient NTC circuits and architectures is achieved by a series of cross-layer techniques from circuit, logic design and automation flows all the way to the system architecture for NTC. We specifically proposed to develop i) logic and memory optimization to operate reliability at near threshold regime, ii) runtime tuning and adaptation to predict and mitigate failures due to near threshold operation, and iii) embracing residual errors in near threshold computing through approximate computing.