Yes, you should always add the following monitor counters for each Load Generator and the Controller machine during a load test. This will ensure that you are not overloading your Load Generators or the Controller's system resources and the cause of a bottleneck or failures in a test.
This is a minimum monitor set for Load Generators and the Controller. Use as a minimum, the following counters:
* Memory -- Available Mbytes
* Processor -- %Processor Time _Total
* System -- Process Queue Length
* Physical Disk -- Current Disk Queue Length _Total
* Private bytes of the mmdrv process, to keep track of its memory consumption