Performance Issues in WWW Servers

This paper evaluates performance issues in WWW servers on UNIX-style platforms. While other work has focused on reducing the use of kernel primitives, we consider ways in which the operating system and the network protocol stack can improve support for high-performance WWW servers. We study techniques in 3 categories: new socket functions, per-byte optimizations, and per-connection optimizations. We examine two proposed socket functions, acceptex() and send file(), comparing send file()'s effectiveness with an mmap()/writev()combination. We show how send file()provides the necessary semantic support to eliminate copies and checksums in the kernel, and quantify the utility of the function's header and close options. We also present mechanisms to reduce the number of packets exchanged in an HTTP transaction, both increasing server performance and reducing network utilization, without compromising interoperability. We evaluate these issues with a high-performance WWW server, using IBM AIX ..