Patent ID: 7441135

Claim:
A method for managing power consumption in a system comprising at least two computing devices, the method comprising: providing one or more computing devices in a first group of active computing devices each adapted for processing a computational workload, and, sensing a state of processing operations at said active computing devices, receiving, at a control device, a signal requesting that additional computing devices from a second group of inactive computing devices be added to the first group of active computing devices, or that computing devices from the first group of active computing devices be placed in the second group of inactive computing devices according to said state of processing operations; determining, by said control device, a system transition time TT value for moving one or more computing devices from the second group of ready computing devices to said first group of active devices, and comparing said TT value against a minimum value, M_min, representing a minimum acceptable delay time for switching a standby computing device from said second group of ready computing devices to said first group of active computing devices and, against a maximum value, M_max, representing a maximum delay interval when all computing devices are in a powered off state; the control device further dynamically generating a readiness index parameter RI t at a current time indicating a state of system readiness where RI t is a real number from 0 to 1, where 0 represents minimum readiness and 1 represents maximum readiness, said RI t calculated according to one of: RI t =RI t−1 +(TT−M_min)/M_max, when increasing system readiness according to a predetermined system response time policy, or, RI t =RI t−1 −(TT−M_min)/M_max, when decreasing system readiness according to a predetermined system response time policy, and, where RI t−1 is a RI value prior to said current time; and, dynamically allocating, by said control device, one or more computing devices in said second group of ready computing devices in various stages of stand-by, hibernating and power-off readiness according to a value of said readiness index parameter, wherein if RI=0, all N ready computing devices in the second group are in powered-off state where N=number of total ready computing devices in the second group; and, if RI=1, all N ready computing devices in the second group are in one of: standby state or hibernating state; wherein, a time it takes to bringing a computing device from said second group of ready computing device to an active readiness state in said first group is minimized, while maximizing energy savings in said system.