Holistically evaluating the environmental impacts in modern computing systems

There is mounting evidence that manufacturing energy and environmental costs are a growing factor in the overall energy footprint of computing systems. The quantification of these impacts requires the evaluation of both the manufacturing and use phase energy/environmental costs of major integrated circuit (IC) components, including processing units, memory, and storage. In particular, expansions of memory and cache can potentially increase manufacturing costs beyond what can be recovered through use phase advantages for reasonable usage patterns. With this holistic view of sustainability in mind, we provide evaluations of the environmental impacts of memory and cache options for Parsec and SPEC multi-program workloads. Using indifference point analysis, we determine which architectural decisions are the most sustainable in the context of these workloads for various usage scenarios. Through a form of break even analysis, we show the impact of upgrading to a new technology node. Our analysis of current processor trends indicates that upgrading may require upwards of 10 years of service time to break even, and that designing systems with smaller cache and main memory sizes may provide an overall positive environmental trend without dramatically reducing performance.