Admission Control with Service Level Agreements for a Web Server

One problem with web servers is that they are sensitive to overload. The servers may become overloaded during temporary traffic peaks when more requests arrive than the server is designed for. Because overload usually occurs rather seldom, it is not economical to overprovision the servers for these traffic peaks, instead admission control mechanisms can be implemented in the servers. This paper investigates two overload control strategies with performance bounds for a web server. In service level agreements, we bound average response times and throughputs for all service classes. Each request is sorted into a class, where each class is assigned a weight representing the income for the web site owner. Then a linear optimization algorithm is applied so that the total revenue for the web site during overload is maximized.