Support for Linux kernel AIO (Asynchronous I/O) has been included in the version 2.6. By enabling Lighttpd AIO you can gain good performance gain. But what is AIO?
Usually your application needs to wait till I/O call is finished. AIO enables even a single application thread to overlap I/O operations with other processing, by providing an interface for submitting one or more I/O requests in one system call without waiting for completion, and a separate interface to reap completed I/O operations associated with a given completion group (see Linux AIO home page for more details).
Lighttpd 1.5.x support AIO. First make sure you have libaio installed:
# yum install libaio-devel
Next grab lighttpd source code and compile with --with-linux-aio option:
# ./configure --with-openssl --with-linux-aio
# make; make install
Save and close the file. Restart lighttpd:
# /etc/init.d/lighttpd restart
Use httpd_load / ab command Performance Benchmarks a Web server.
Please note that I’ve tested above instructions on Redhat Enterprise Linux 4/5 and Cent OS.