基于流媒体文件字节有用性的代理服务器缓存替代策略

Proxy Cache Replacement Strategies Based on Bytes Benefit of Streaming Media File

将流媒体文件缓存到离用户最近的代理服务器上 ,能够减少广域网络带宽的消耗 ,减轻服务器的负载压力以及降低用户的始播延迟 ,文章关注代理服务器的缓存替代问题 .通过对问题建立模型并分析后得到替代算法模型 ,提出了流媒体文件字节有用性的概念并反映到替代算法的设计之中 ,并提出了BB ,BBLRU K和BBLCB K缓存替代算法 ,在与LRU 2 ,LFU ,LCB 2和LRU等算法的性能模拟实验比较中 ,BBLCB 2算法性能最优 ,但BB算法简单有效 .

This paper discusses the problem about cache replacement strategy on the proxy where the remote streaming media files were replicated by which the client startup delay, the server traffic and the wide area network bandwidth could be reduced. Cache replacement strategy is an approach by which the proxy can collect available space in order to cache object by filtering out the least valuable object in the cache one by one. The least valuable object is determined by ranking object values. Thus, the value function is a key issue having a great impact on performance measurement such as hit ratio and byte hit ratio. By formulating a model of replacement algorithm based on the analysis of cache replacement in streaming media systems, authors put forword the concept of bytes benefit of streaming media file and apply it to the design of replacement algorithms, and propose BB, BBLRU-K and BBLCB-K replacement algorithms. The concept is formed by the fact that someone does not usually use a streaming media file completely, which means that we can evaluate the file's values based on the used bytes number of the file. Simulation indicates that among these algorithms and existing algorithms such as LRU-2, LFU, LCB-2, and LRU, BBLCB-2 has the best average performance, while BB is simple and efficient, only relate to the bytes benefit of streaming media file and its performance is very close to the BBLCB-2.