Hint-based acceleration of Web proxy caches

Numerous studies show that proxy cache miss ratios are typically at least 40%-50%. This paper proposes and evaluates a new approach for improving the throughput of proxy caches by reducing cache miss overheads. An embedded system able to achieve significantly better communications performance than a traditional proxy filters the requests directed to a proxy cache, forwarding the hits to the proxy and processing the misses itself. This system, called a Proxy Accelerator, uses hints of the proxy cache content and may include a main memory cache for the hottest objects. Scalability with the Web proxy cluster size is achieved by using several accelerators. We use analytical models and trace-based simulations to study the benefits and the implementation tradeoffs of this new approach. A single proxy accelerator node in front of a four-node Web proxy improves the cost-performance ratio by about 40%. Implementation choices that do not affect the overall hit ratio are available.