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Abstract : |
Many proxy servers that run on today's computers are limited by their file I/O needs. Even if the proxy is configured with sufficient I/O hardware, the file system software often fails to provide the available bandwidth to the proxy processes. Although specialized file systems may offer a significant improvement and overcome these limitations, we believe that user-level disk management on top of industry standard file systems can offer comparable performance. In this paper we study the overheads associated with file I/O in web proxies, we investigate their underlying causes, and we propose web-conscious storage management: a set of techniques that exploit the unique reference characteristics of web-page accesses in order to allow web proxies to overcome file I/O limitations. Using realistic trace-driven simulations we show that the proxy's secondary storage I/O throughput can be improved by a factor of 18, enabling a single-disk proxy to serve around 500 (URL-get) operations per second. We demonstrate the applicability of our approach by implementing Foxy, a web proxy which incorporates our web-conscious storage management techniques. Our experimental evaluation suggests that Foxy outperforms traditional proxies such as SQUID by more than a factor of 7 under heavy load. 1, |
