Green Metrics for Energy-aware IT Systems

This paper presents a novel approach to characterise applications with respect to their energy consumption by using a set of energy-related metrics, called Green Metrics. These indicators are based on energy consumption measurements, such as indexes of computing resource usage, of environmental impact, and even of development costs required to (re)design an application in order to optimise its energy consumption footprint, or of organizational factors related to application management. Our approach is framed in the GAMES (Green Active Management of Energy in IT Service centres) EU Project1 about green IT. In this paper, we define four clusters of Green Metrics enabling to feature an application in terms of the energy it consumes at run time. Such metrics are the basis for measuring the "greenness" of an application and to detect where it consumes and wastes energy. Hints are provided to improve applications design and execution. We show within an application scenario how monitoring and evaluation of the Green Metrics helps to improve energy efficiency.