Class-Based Latency Assurances for Web Servers

This paper presents a fuzzy control approach for process assignment in order to guarantee absolute percentile delay in web servers. Comparing with mean delay used in previous works, percentile delay introduces strong nonlinearities to the plant; it is therefore difficult to achieve satisfactory performance by a linear controller, which is commonly used to guarantee mean delay performance. In this paper we propose a fuzzy controller. Its key feature is independence of the plant and robust to model uncertainty, which is very suitable to the strong nonlinear web servers. The experiments have demonstrated the efficiency of the proposed fuzzy controller in handing the variety of requests.