Web server performance in a WAN environment

This work analyzes web server performance under simulated WAN conditions. The workload simulates many critical network characteristics, such as network delay, bandwidth limit for client connections, and small MTU sizes to dial-up clients. A novel aspect of this study is the examination of the internal behavior of the web server at the network protocol stack and the device driver. Many known server design optimizations for performance improvement were evaluated in this simulated environment. We discovered that WAN network characteristics may significantly change the behavior of the web server compared to the LAN-based simulations and make many of optimizations of the server design irrelevant in this environment. Particularly, we found out that small MTU size of the dial-up user connections can increase the processing overhead several times. At the same time, the network delay, connection bandwidth limit, and usage of HTTP/1.1 persistent connections do not have a significant effect on the server performance. We have found there is little benefit due to copy and checksum avoidance, optimization of request concurrency management, and connection open/close avoidance under a workload with small MTU sizes, which is common for dial-up users.