Dark Silicon Considered Harmful: A Case for Truly Green Computing

As individuals and researchers approach the challenge of green computing it is natural to consider the energy consumption of computational devices and their supporting systems during their use phase (i.e., after they are deployed into service). However, for computing to be truly green, all phases of the system life-cycle, from manufacturing to disposal, must be considered. In particular there is limited awareness to the considerable fraction of the total life-cycle environmental impacts of computing systems that result from the fabrication of the integrated circuits (ICs) that are used in those devices. Ironically, the trend toward dark silicon accelerators, often targeted at improving operational energy efficiency, may be counterproductive for holistic energy reduction of computing systems. The increased chip area that results from a large percentage of dark silicon may exacerbate the fabrication impacts to the point that overall sustainability is actually decreased. In this paper, we explore some properties of manufacturing and operational energy efficiency and make a case that truly green computing must carefully consider the tradeoffs involved.