EnergySmart: Toward energy-efficient manycores for Near-Threshold Computing

While Near-Threshold Voltage Computing (NTC) is a promising approach to push back the manycore power wall, it suffers from a high sensitivity to parameter variations. One possible way to cope with variations is to use multiple on-chip voltage (V_dd) domains. However, this paper finds that such an approach is energy inefficient. Consequently, for NTC, we propose a manycore organization that has a single V_dd domain and relies on multiple frequency domains to tackle variation. We call it EnergySmart. For this approach to be competitive, it has to be paired with effective core assignment strategies and also support fine-grain (i.e., short-interval) DVFS. This paper shows that, at NTC, a simple chip with a single V_dd domain can deliver a higher performance per watt than one with multiple V_dd domains.