The Architectural Sustainability Indicator

Computing devices are responsible for a significant fraction of the world’s total carbon footprint. Designing sustainable systems is a challenging endeavor because of the huge design space, the complex objective function, and the inherent data uncertainty. To make matters worse, a design that seems sustainable at first, might turn out to not be when taking rebound effects into account. In this paper, we propose the Architectural Sustainability Indicator (ASI), a novel metric to assess the sustainability of a given design and determine whether it is strongly, weakly, or unsustainable. ASI provides insight and hints for turning unsustainable and weakly sustainable design points into strongly sustainable ones that are robust against potential rebound effects. A case study illustrates how ASI steers Scalar Vector Runahead, a weakly sustainable hardware prefetching technique, into a strongly sustainable one while offering a 3.2× performance boost.