Performance Tuning Garbage Collection in Java: "2.1 Performance Considerations
Ways to measure GC Performance
Throughput - % of time not spent in GC over a long period of time.
Pauses - app unresponsive because of GC
Footprint - overall memory a process takes to execute
Promptness - time between object death, and time when memory becomes available
There is no one right way to size generations, make the call based on your applications usage."