Web QoS Control Using Fuzzy Adaptive PI Controller

This paper researches on QoS (Quality of Service) control problems for web servers. A Fuzzy Adaptive PI Control system is proposed in this paper. Via a basic PI controller, the system can dynamically adjust the ratio of request-accepting time in a control period, in order to turn down requests when the server is overloaded. Considering that in a real Internet environment, the network and server load are continually varying in an uncertain range, we use a fuzzy control approach to tune the PI parameters adaptively. Details of the fuzzy control approach are elaborated in this paper. Simulation results demonstrate that in a stable server load environment, the Fuzzy Adaptive PI Control system works as well as the basic PI controller, but it acts much more stably and rapidly dealing with fluctuating loads.