全球資訊網伺服器上快取記憶體的設計與實作

Abstract

隨著全球資訊網的盛行，其資料量的成長已是所有網際網路資料量中成 長的最迅速者。然而，如此龐大的資料量卻使得全球資訊網的使用者花費 漫長的時間在文件擷取上。因此，便有研究人員開始致力於減少全球資訊 網文件的擷取時間。要降低全球資訊網文件的擷取時間主要有兩種方法︰ 降低網路傳輸時間及提高全球資訊網伺服器的效能。而我們的研究主要就 是藉由在伺服器的位址空間中保留一個快取記憶體來提高全球資訊網伺服 器的效能。在本論文中，我們著重於此快取記憶體的設計與實作，同時也 提出了一個嶄新的全球資訊網快取記憶體的管理方法。實驗結果證明了三 件事。第一，一個大小只有全部資料 1.8% 的快取記憶體就可以使全球資 訊網伺服器的效能提高16.9%。 第二，我們的快取記憶體管理方法適用於 目前全球資訊網的運輸模式。第三，隨著多媒體檔案的盛行，很有可能出 現一個檔案比整個快取記憶體還要大的情況。在這種情況下，我們的快取 記憶體管理方法會比目前其他的方法更有效率。 With the popularity of the World Wide Web( WWW ), web traffic has become the fastest growing component among all kinds of Internet traffics. However, so large volumes of traffic causes the document retrieval latency perceived by web users becomes longer.Many researchers notice the problem and have made efforts on improving the WWW latency. The latency can be reduced in two ways: the reduction of network delay and the improvement of web server's throughput. Our research aims at improving web server's throughput by keeping a memory cache in a web server's address space. In this thesis, we focus on the design and implementation of a memory cache. We propose a novel web cache management policy. The experiment results show three things. First, our memory cache is beneficial since, by keeping a cache which it size is only 1.8% of total document size, the throughput improvement can achieve 16.9%.Second, our cache management policy is suitable for current web traffic. Third, with the increasing popularity of multimedia files, it is very likely that a file is larger than the total size of the memory cache. Under this condition, our policy will outperform others that are currently used in WWW.