The Bandwidth Differentiated Service of Web Server

Differentiated service which belongs to the research of internet QoS means the requests with high priority should receive the quality of service “at least not lower than” the low priority. As we know, what clients most concerned is whether there is a small delay for an important request. The client-perceived delay is composed of connection delay and processing delay. So far, the QoS researches most focus on the connection delay that can be controlled by the threads / processes allocation. However, the experiments show that it is invalid when the bandwidth becomes the resource bottleneck. For this issue, the paper proposes bandwidth based QoS architecture to takes the processing delay into consideration. The self-tuning controller adjusts the bandwidth allocated to different virtual hosts to control the processing delay. The experiments show that the algorithm not only achieves the proportional delay guarantees but also emerges its advantage on the stability. Compared with the static fuzzy controller, the variance between the real delay proportion and the expect value is deceased 40% by the self-tuning control.