Note that median total delay may differ from median response time because of pipelining and such non-accounted activities as DNS lookups. We are working on a more precise model that accounts for these side effects. We cannot account for pipelining affects that may change relative contributions for large requests. We believe that our estimations are very close to actual performance. The graph shows relative contribution of each stage towards total delay.
Total delay is calculated as a sum of delays of all stages.
The graph shows the number of concurrent swap requests present in the proxy server. We count the number of requests in the system using 2 msec intervals and calculate the median based on 20 minute grouping. We plot the 50th and 75th percentiles. The 50th percentile is the same as median. Disk Utilization Disk utilization is measured in the percent of time there was at least one active swap request.