Proportional Hit Rate in Caching Service: A Feedback Control Approach

As the heterogeneity of Web clients increasing, the differentiated service (DifferSer) becomes an important issue especially for e-commerce Web site. Web caching as a key accelerator on the internet plays an important role in alleviating the client-perceived delay. Based on feedback control theory, this paper proposes an isolated cache model and designs a storage controller to achieve proportional hit rate. Through system identification, the linear model of isolated cache is identified to design controller. At each sampling time, by dynamically reallocating cache spaces between different web objects, the controller could guarantee the priority Web objects a higher hit rate and the proportions of hit rates between different kinds of Web objects constant. The experimental results demonstrate the proposed approach achieves the proportional hit rat guarantee under GDSF, LRU and LFU cache replacement algorithms.