Apache HTTP Server Version 2.4
Apache HTTP Server Version 2.4
Apache 2.x is a general-purpose webserver, designed to provide a balance of flexibility, portability, and performance. Although it has not been designed specifically to set benchmark records, Apache 2.x is capable of high performance in many real-world situations.
Compared to Apache 1.3, release 2.x contains many additional optimizations to increase throughput and scalability. Most of these improvements are enabled by default. However, there are compile-time and run-time configuration choices that can significantly affect performance. This document describes the options that a server administrator can configure to tune the performance of an Apache 2.x installation. Some of these configuration options enable the httpd to better take advantage of the capabilities of the hardware and OS, while others allow the administrator to trade functionality for speed.
Hardware and Operating System Issues Run-Time Configuration Issues Compile-Time Configuration Issues Appendix: Detailed Analysis of a Trace
The single biggest hardware issue affecting webserver
performance is RAM. A webserver should never ever have to swap,
as swapping increases the latency of each request beyond a point
that users consider "fast enough". This causes users to hit
stop and reload, further increasing the load. You can, and
should, control the MaxRequestWorkers setting so that your server
does not spawn so many children that it starts swapping. The procedure
for doing this is simple: determine the size of your average Apache
process, by looking at your process list via a tool such as
top, and divide this into your total available memory,
leaving some room for other processes.
Beyond that the rest is mundane: get a fast enough CPU, a fast enough network card, and fast enough disks, where "fast enough" is something that needs to be determined by experimentation.
Operating system choice is largely a matter of local concerns. But some guidelines that have proven generally useful are:
Run the latest stable release and patch level of the operating system that you choose. Many OS suppliers have introduced significant performance improvements to their TCP stacks and thread libraries in recent years.
If your OS supports a sendfile(2) system
call, make sure you install the release and