Admission Control for Web Server Systems

Björn Wittenmark
Department of Automatic Control
Lund Institute of Technology

In communication systems, all service control nodes, such as for example web sites or Mobile Switching Centers, can be modeled as a server system with one or more servers processing the incoming requests. To avoid overload at the service node some type of admission control mechanism is usually implemented to guarantee good performance also during high traffic loads. In this paper we investigate, from a control point of view, the nonlinear discrete- time modeling of a server system, and the analysis and design of load control mechanisms based upon this model. Verification of the server model behavior with respect to queue theoretic models are made and the load control mechanisms are implemented on an Apache web server and experimentally evaluated.

The seminar is based on research done together with Anders Robertsson, Maria Kihl, and Mikael Andersson and has been presented at ACC'03, ACC'04, and CDC'04.