Controlling the Power Consumption of Computers

1 . A system, comprising:

a group of computers including a group power controller, wherein each computer of the group has a performance monitor for monitoring a measure of performance of the computer, and the measure of performance is the value of at least one performance metric of the computer excluding contributions to the activity metric(s) of one or more predetermined activities,

wherein the group power controller is configured to allocate to the computers of the group shares of a maximum power consumption of the group, the shares being allocated in dependence on the said monitored measures of performance, and

wherein each computer of the group has an individual power controller configured to limit the power consumption of the computer to the share allocated by the group power controller.

2 . The system according to claim 1 , wherein the power controller comprises a computer additional to said computers having performance monitors and individual power controllers.

3 . The system according to claim 1 , wherein the power controller comprises one of the computers having performance monitors and individual power controllers.

4 . The system according to claim 1 , wherein any of the computers of the group having a performance monitor is configured to adopt a predetermined low power state if the measure of performance is less than a threshold value, the group power controller being responsive to the adoption of the state to reallocate the shares of the group maximum power consumption to the others of the computers which are not in the state.

5 . The system according to claim 4 , wherein each of the computers of the group having a performance monitor is configured to adopt the predetermined low power state if the measure of performance is less than a threshold value for a predetermined period of time.

6 . The system according to claim 1 , wherein the group power controller is configured to allocate the shares to the computers according to preset rules.

7 . The system according to claim 6 , wherein the computers are allocated different statuses and the group power controller is configured to allocate the shares according to the statuses of the computers.

8 . A computer-implemented method of controlling the power consumption of a group of computers including a group power controller, the method comprising:

monitoring a measure of performance of each computer of the group, wherein the measure of performance is the value of at least one performance metric of the computer excluding contributions to the activity metric(s) of one or more predetermined activities;

allocating to the computers of the group shares of a maximum power consumption of the group, the shares being allocated by the group power controller in dependence on the monitored measures of performance; and

limiting the power consumption of each computer to the share allocated by the group power controller.

9 . A non-transitory computer readable medium, or a set of non-transitory computer readable media, having instructions stored thereon for execution by a group of computers, the instructions configuring the computers of the group to:

monitor a measure of performance of each computer of the group, wherein the measure of performance is the value of at least one performance metric of the computer excluding contributions to the activity metric(s) of one or more predetermined activities;

allocate to the computers of the group shares of a maximum power consumption of the group, the shares being allocated by the group power controller in dependence on the monitored measures of performance; and

limit the power consumption of each computer to the share allocated by the group power controller.

10 . A computer for use in the system according to claim 1 , the computer including:

a performance monitor for monitoring a measure of performance of the computer, wherein the measure of performance is the value of at least one performance metric of the computer excluding contributions to the activity metric(s) of one or more predetermined activities;

an interface for receiving, from a group power controller, data representing a share of the maximum power consumption of the group; and

an individual power controller configured to limit the power consumption of the computer to the share allocated to the computer.

11 . A non-transitory computer readable medium, having instructions stored thereon for execution by a computer of a group of computers, the instructions configuring the computer to:

monitor a measure of performance of the computer, wherein the measure of performance is the value of at least one performance metric of the computer excluding contributions to the activity metric(s) of one or more predetermined activities;

receive, from a group power controller, data representing a share of the maximum power consumption of the group; and

limit the power consumption of the computer to the share allocated to the computer.

12 . A group power control computer for use in the system according to claim 1 , the power control computer including an interface for receiving from other computers of the group data representing monitored measures of performance of the other computers of the group, the power control computer being configured to allocate, to the other computers of the group, shares of a maximum power consumption of the group, the shares being allocated in dependence on the said received measures of performance.

13 . A non-transitory computer readable medium, having instructions stored thereon for execution by a power control computer for use in a group of computers, the instructions configuring the computer to:

receive from other computers of the group data representing monitored measures of performance of the other computers of the group; and

allocate, to the other computers of the group, shares of a maximum power consumption of the group, the shares being allocated in dependence on the received measures of performance.