ReDEEM: A heterogeneous distributed microarchitecture for energy-efficient reliability

Diminishing energy-efficiency returns and decreasing transistor reliability are casting shadows on semiconductor scaling. Prior research has been addressing processors´ energy-efficiency and transistor reliability as orthogonal problems. However, as embedded processors become more powerful and find their way into more diverse applications, both high reliability and energy-efficiency become critical. In this work, we propose ReDEEM, a novel approach to design energy-efficient and reliable microarchitectures. Our proposed solution composes processor pipelines at runtime from redundant but heterogeneous pipeline components. Our pipeline components are loosely coupled and the control logic is decentralized so as to enable fault isolation and thereby eliminate single points of failure. We equip the microarchitecture with the ability to adapt dynamically to varying application phases by constructing energy-efficient pipelines best suited for each phase. In addition, pipeline components have power management capabilities that allow for greater energy efficiency and flexibility. Our experimental evaluation shows that our solution offers up to 60% in energy savings and can operate about 1.8x longer, when subjected to the same fault rate as a state-of-the-art reliable microarchitecture.