How to set the time in rally so that it can perform (time * events/s) events to benchmark the cpu usage and memory usage

I want to benchmark the cpu usage and memory usage for specific time with events/s
that is if we have 500 events/s and set time for 900s so processing should be for 900 * 500 events
So at that moment what would be the cpu usage and memory usage ?

You should be able to do this by specifying a target-throughput and a duration instead of the number of iterations.