Apache Benchmarking
They're few tools out there which are most common in use to do
benchmarking and stess test on webservers. One of them "the most
common one" is called "ab" or apache benchmark
Check it out
here another very common tool is called flood
Check it here Flood seems
to be the newer and most accurate tool to use for stress testing
unfortunately it has one weakness. It only works with configuration
file which is in xml format. So every time before you start it you
have to generate a new xml file to suite your needs. Also a tool
recommended to me in the #apache in the irc.freenode.net network is
called "jmeter", it's located
here . I personally didn't
tested it because it uses Java as a back end. While googling around
I also have stucked on this interesting project
PHPSPEED although I wasn't able to
test it looks like a promising test suite.