This function can be implemented by using theipvsadm command. We measured AC power, that is, the output of the inverter, but not DC power, that of the battery, so that these data can be referred to in a different experimental environment, such as using commercial AC power for power supply. We compared energy-proportional control to the conventional method in which all web servers are always active, in Figure 9. The results show that there are no differences between these two methods in terms of response times.