Are you talking about site load or server load? If you want to measure the load on a server, look into the sar utility, which is included in Linux and all ot

Are you talking about site load or server load? If you want to measure the load on a server, look into the sar utility, which is included in Linux and all other Unix'es. It will take snapshots of data at 10 minute intervals and store them. Other tools will take that data and turn it into a bar graph or other visualization.