Web缓存的一种新的替换算法

现有的Web缓存器的实现主要是基于传统的内存缓存算法,然而由于Web业务请求的异质性,传统的替换算法不能在Web环境中有效工作.首先给出了问题的一个最优化模型,分析了替换算法的关键在于能正确地体现Web业务的访问模式.在泊松到达模型的基础上,提出一种新的缓存策略--最少正规化代价替换算法(leastnormalized-cost,简称LNC).新的替换算法除了考虑Web文档的平均引用时间、最近流逝时间、文档大小和单位大小价值以外,还考虑了Web业务的访问率动态改变的特征.对轨迹文件所做的性能实验表明,LNC优于其他主要的算法.

A Novel Replacement Algorithm for Web Caching

Currently, the implementation of WEB caching is mostly based on traditional cache updating algorithms. However, due to the diversity of the WEB traffic pattern, the traditional algorithms for cache updating can not be used in WEB environment effectively. In this paper, an optimized model to the problem is presented. The analytic result shows that the key issue for the cache updating algorithms is how the algorithm suits the WEB traffic pattern properly. Based on the Poisson arrival model, a new cache policy, Least Normalized Cost (LNC), is proposed. In addition to the consideration of the average reference time duration, the recently passed time, the size of the WEB file and the cost per unit of file, the dynamic characteristic of WEB access rate is also taken into account. The trace driven simulation shows that the performance of the algorithm LNC is better than that of the existing algorithms proposed in the literature.