This software is created to give you an impression of how your Apache server works. Also you can test how many requests per second your Apache server is capable of serving. HSLAB Apache Load Simulator is a great way to really put stress on a server.

HSLAB Apache Load Simulator runs multiple http clients in parallel, to test the performance of a web server. However unlike most such test clients, it runs in a single process, so it doesn't slow down the client machine. It can be flexible configured to use https clients as well.
You can benchmark Apache, IIS or any other web server with this HSLAB Apache Load Simulator benchmarking tool.
First of all, server benchmarking is not a trivial thing. To benchmark your server the time it will take to send a page to the client is not very important and you don't care if a user can load the page in 1 millisecond or in 5 milliseconds as nobody can have such delays in network or on the Internet.

Most important is the average time to take a page when you have a maximum number of clients on your server simultaneously. Alsoimportant thing is how much more time it will take when there are 2 times more clients: a server that takes 2 times more for 2 times more clients is better than another that takes 4 times more for the same number of clients.

Web server benchmark procedure

• Use identical hardware and software configuration, kernel for all tests
  
• Use identical network configuration. For example, use 1000Mbps network adapter for all tests
  
• Before testing record server load using HSLAB HTTP Monitor, uptime or  top tools
  
• Take at least 3…4 or more readings and use the average results
  
• After each test you should reboot your server and continue your test on next web server configuration
  
• Record server load again using HSLAB HTTP Monitor,  uptime or  top tools
  
• Continue your test using static html or php pages and dynamically created pages and scripts
  
• It also very important to run tests using the KeepAlive and Non-KeepAlive  features (the Keep-Alive module  provides long-lived sessions, which allows clients to send multiple requests over the same connection).

Also  test your server using fast-cgi and perl scripts.