基于自适应模糊控制的Web带宽区分服务

Bandwidth Differentiated Service in Web Server Based on Self-tuning Fuzzy Control

基于线程/进程分配的Web区分服务策略仅仅关注连接延迟,而在服务器带宽受限的情况下,由于处理延迟成为客户端总延迟的主导部分,因此区分效果很差。提出的基于带宽调节的区分服务策略,通过两级自适应模糊控制,调整服务于不同优先级请求的虚拟主机的带宽配额,从而控制处理延迟,实现比例延迟保证。经稳定性分析与实验验证,这种方法取得了良好的效果,相对于静态模糊控制,其延迟比与期望值的方差减少了40%。

The strategy of differentiated service based on process allocation only concerns connection delay, but when the bandwidth of Web server is over-subscribed, such method is ineffective because the processing delay becomes the dominant factor of client-perceived delay. This paper proposed a QoS strategy using two-level fuzzy control, by adjusting the bandwidth of virtual hosts that sever the different priority requests,the self-tuning fuzzy controller could affect the processing delay and achieve the proportional delay guarantee. The stability analysis and experimental results demonstrate that the proposed approach achieves a better performance in terms of the proportional delay variance to the target. The self-tuning fuzzy controller outperforms the static fuzzy controller by 40% on average.