Statistical QoS Guarantee and Energy-Efficiency in Web Server Clusters

In this paper we study the soft real-time web cluster architecture needed to support e-commerce and related applications. Our testbed is based on an industry standard, which defines a set of web interactions and database transactions with their deadlines, for generating real workload and benchmarking e-commerce applications. In these soft real-time systems, the quality of service (QoS) is usually defined as the fraction of requests that meet the deadlines. When this QoS is measured directly, regardless of whether the request missed the deadline by an epsilon amount of time or by a large difference, the result is always the same. For this reason, only counting the number of missed requests in a period avoids the observation of the real state of the system. Our contributions are theoretical propositions of how to control the QoS, not measuring the QoS directly, but based on the probability distribution of the tardiness in the completion time of the requests. We call this new QoS metric ...

• Type: Conference
• Year: 2007
• Where: ECRTS
• Authors: Luciano Bertini, Julius C. B. Leite, Daniel Mossé
• Keywords: ECRTS 2007, Embedded Systems, Qos Metric Tardiness, Soft Real-time, Web Cluster