Web Performance Tuning

History and Introduction

This page and the related work have been long in the making. I started out peering wide-eyed over the shoulders of two people from a search engine provider when they were installing a German version of their server for a customer of my former employer. My only alternative resource for tuning information was the brilliant book TCP/IP Illustrated, Volume 1, by Richard Stevens. I then started collecting as much information about tuning as I was able to get my hands on. You have the result in front of you on these pages.

Solaris allows you to tune, tweak, set, and reset various parameters related to the TCP/IP stack while the system is running. Back in the SunOS 4.x days, one had to change various C files in the kernel source tree, generate a new kernel, reboot the machine, and try out the changes. The Solaris feature of changing the important parameters on the fly is very convenient.

Many of the parameters I mention in the rest of the document you are reading are time intervals. All intervals are measured in milliseconds. Other parameters are usually bytecounts, but occasionally different units of measurements are used and documented. A few items appear totally unrelated to TCP/IP, but due to the lack of a better framework, they materialized on this page.

Most tuning parameters can be changed using the program ndd. Any user may execute this program to read the current settings, depending on the readability of the respective device files, but only the superuser ...