On comparing load indices using oracle simulation

Oracle simulation is used to compare different load measures in terms of their impact on the performance of load balancing policies. During oracle simulation, the system is simulated and the performance measure of interest is evaluated in the future for each possible decision in the current state. By comparing the value of the performance measure in the future, the optimal decision for the current state can be reached. It is shown that the obvious load measures can be classified into two sets. The first set includes the instantaneous queue length, average queue length, utilization, response ratio, and total unfinished work. Any of these measures can greatly improve system performance. The other set includes arrival rate and throughput. These measures have only a slight effect on performance. The performance of practical load balancing policies that do not use future information supports the same conclusion