Measurement tools and modeling techniques for evaluating web server performance

The past few years have seen a rapid growth in the popularity of the Internet and the World Wide Web. Many companies are deploying Web servers and seeing their usage rates climb rapidly over time. Our research focused on analyzing and evaluating the performance of Internet and intranet Web servers with a goal of creating a Layered Queueing Model to allow capacity planning and performance prediction of next generation server designs. To achieve this we built a tool framework that enables us to collect and analyze empirical data necessary to accomplish our goals. This paper describes custom instrumentation we developed and deployed to collect workload metrics and model parameters from several large-scale, commercial Internet and intranet Web servers over a time interval of many months. We describe an object-oriented tool framework that significantly improves the productivity of analyzing the nearly 100 GBs of collected measurements. Finally, we describe the layered queueing model we developed to estimate client response time at a Web server. The model predicts the impact on server and client response times as a function of network topology and Web server pool size.