Edited by one of the founders and lead investigator of the Green500 list, this book presents state-of-the-art approaches to advance the large-scale green computing movement. It begins with low-level, hardware-based approaches and then traverses up the software stack with increasingly higher-level, software-based approaches. The book explains how to control power across the hardware, firmware, operating system, and application levels and explores trends in server costs, energy use, and performance at high-density computing facilities. It also discusses energy management and virtualization in cloud computing.