Dynamic Voltage Scaling in Multitier Web Servers with End-to-End Delay Control

• Published in: IEEE transactions on computers Vol. 56; no. 4; pp. 444 - 458
• Main Authors: Horvath, T., Abdelzaher, T., Skadron, K., Xue Liu
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.04.2007; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Delay; distributed algorithms; Electric potential; Energy conservation; Energy consumption; network servers; optimization methods; pipeline processing; Pipelines; Power management; Servers; Servers (computers); soft real-time systems; Studies; voltage control; World Wide Web
• ISSN: 0018-9340; 1557-9956
• DOI: 10.1109/TC.2007.1003

The energy and cooling costs of Web server farms are among their main financial expenditures. This paper explores the benefits of dynamic voltage scaling (DVS) for power management in server farms. Unlike previous work, which addressed DVS on individual servers and on load-balanced server replicas, this paper addresses DVS in multistage service pipelines. Contemporary Web server installations typically adopt a three-tier architecture in which the first tier presents a Web interface, the second executes scripts that implement business logic, and the third serves database accesses. From a user's perspective, only the end-to-end response across the entire pipeline is relevant. This paper presents a rigorous optimization methodology and an algorithm for minimizing the total energy expenditure of the multistage pipeline subject to soft end-to-end response-time constraints. A distributed power management service is designed and evaluated on a real three-tier server prototype for coordinating DVS settings in a way that minimizes global energy consumption while meeting end-to-end delay constraints. The service is shown to consume as much as 30 percent less energy compared to the default (Linux) energy saving policy