When a request hits a cache, the proxy can reply immediately. As the hit rate increases, the mean retrieval time decreases. We collected references and calculated the hit rate using 8,519 clients requests in the log. Figure 3 shows the relation between the hit rate and the number of prefetching targets. The hit rate increases as the number of prefetching targets increases.
Many requests are to retrieve referenced pages in a page.
The hit rate is similar to the exponential function. However, the prefetching system puts a heavy load onto the host. As the number of prefetching targets increases, the hit rate and the load increase. Therefore, we should consider the balance between the load and the hit rate. The Wcol runs on most popular UNIX platforms.