Abstract
Server performance has become a crucial issue for improving the overall performance of the World-Wide Web. This paper describes Webmonitor, a tool for evaluating and understanding server performance, and presents new results for a realistic workload.
Webmonitor measures activity and resource consumption, both within the kernel and in HTTP processes running in user space. Webmonitor is implemented using an efficient combination of sampling and event-driven techniques that exhibit low overhead. Our initial implementation is for the Apache World-Wide Web server running on the Linux operating system. We demonstrate the utility of Webmonitor by measuring and understanding the performance of a Pentium-based PC acting as a dedicated WWW server. Our workload uses a file size distribution with a heavy tail. This captures the fact that Web servers must concurrently handle some requests for large audio and video files, and a large number of requests for small documents, containing text or images.
Our results show that in a Web server saturated by client requests, up to 90% of the time spent handling HTTP requests is spent in the kernel. Furthermore, keeping connections open, as required by TCP, causes a factor of 2 increase in the elapsed time required to service an HTTP request. Data gathered from Webmonitor provide insight into the causes of this performance penalty. These results emphasize the important role of operating system and network protocol implementation in determining Web server performance.
On sabbatical at Boston University from Universidade Federal de Minas Gerais. Partially supported by CNPq-Brazil.
This work was supported in part by NSF grants CDA-9529403 and CDA-9623865.
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© 1997 Springer Science+Business Media Dordrecht
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Almeida, J.M., Almeida, V., Yates, D.J. (1997). Measuring the Behavior of a World-Wide Web Server. In: Tantawy, A. (eds) High Performance Networking VII. HPN 1997. IFIP — The International Federation for Information Processing. Springer, Boston, MA. https://doi.org/10.1007/978-0-387-35279-4_4
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