Progressive CPU sleep state duty cycle to limit peak power of multiple computers on shared power distribution unit
View Patent ↗A method and apparatus for distributing power to a plurality of computers in a network. A power management system including a feed-back mechanism, is employed to monitor power consumptions of the plurality of computers. Should the overall power consumption reach a threshold, the power management system instructs the microprocessors in the plurality of computers to enter into a lower power state, such as a sleep state, for a certain duration, thus lowering overall power.
1. A computer system, comprising:
a power management system; and
a plurality of computers, including a plurality of microprocessors, the plurality of computers coupled to the power management system;
the power management system to monitor a plurality of current demands of the computers, and
the power management system to instruct the plurality of microprocessors to enter into a certain lower power state for a certain duration responsive to changing current demands of the plurality of computers,
wherein the certain duration is a power down duty cycle.
2. The computer system of claim 1 , wherein the microprocessor is a Pentium-type processor.
3. The computer system of claim 2 , wherein the lower power state is a sleep state.
4. The computer system of claim 3 , wherein the plurality of microprocessors can respond to snoops and interrupts in the sleep state.
5. The computer system of claim 3 , wherein the sleep state is a stop-grant state.
6. The computer system of claim 1 , wherein the power management system instructs the plurality of microprocessors to enter into a certain lower power state for certain duration by a command encoded in power lines from the power management system to the plurality of computers.
7. The computer system of claim 1 , wherein the power management system instructs the plurality of microprocessors to enter into a certain lower power state for certain duration by a command over a data link.
8. The computer system of claim 1 , wherein the power management system is not included in one of the plurality of computers.
9. The computer system of claim 1 , wherein the power management system is included in one of the plurality of computers.
10. The computer system of claim 1 , wherein the changing current demands is a cumulative current demand of the plurality of computers.
11. A computer system, comprising:
a power management system; and
a plurality of computers, including a plurality of microprocessors, the plurality of computers coupled to the power management system;
the power management system to monitor a plurality of current demands of the computers, and
the power management system to instruct the plurality of microprocessors to enter into a certain lower power state for a certain duration responsive to changing current demands of the plurality of computers,
wherein the plurality of computers include a plurality of monitors for measuring the plurality of current demands.
12. A method for providing power to a plurality of computers, comprising the steps of:
measuring current demands for the plurality of computers;
calculating a total current demand; and
placing each computer in a lower power state for a selected percentage of time in response to the total current demand exceeding a threshold,
wherein the selected percentage of time varies according to a predefined relationship with respect to the total current demand.
13. The method of claim 12 , wherein the plurality of computers include Pentium-type microprocessors.
14. The method of claim 12 , wherein the lower power state is a sleep state.
15. The method of claim 14 , further comprising the step of responding to snoops and interrupts while each computer is in the sleep state.
16. The method of claim 15 , wherein the sleep state is a stop-grant state.
17. The method of claim 12 , wherein the predefined relationship is a linear relationship between the selected percentage of time and the total current demand over a range of the total current demand.
18. A method for providing power to a plurality of computers, comprising the steps of:
measuring current demands for the plurality of computers;
calculating a total current demand; and
placing each computer in a lower power state for a certain time should the total current demand exceed a threshold,
wherein placing each computer in a sleep state includes asserting a STPCLK signal.
19. A method for providing power to a plurality of computers, comprising the steps of:
measuring current demands for the plurality of computers;
calculating a total current demand; and
placing each computer in a lower power state for a certain time should the total current demand exceed a threshold,
wherein the certain time is a power down duty cycle.
20. The method of claim 19 , wherein the power down duty cycle is less than 90%.
21. A method of managing power in a system having plural computers, comprising:
measuring, with current monitors in respective plural computers, a local current demand of each computer;
calculating a total current demand based on the measured local current demands of the computers; and
placing each computer into a lower power state for a selected time period in response to detecting that the total current demand exceeds a threshold.
22. A system comprising:
a power management controller; and
a plurality of computers coupled to the power management controller,
the power management controller to receive measured local current demands from the computers and to calculate a total current demand based on the measured local current demands,
the power management controller to further place each computer in a lower power state for a selected percentage of time in response to the total current demand exceeding a threshold,
wherein the selected percentage of time varies according to a predefined relationship with respect to the total current demand.
23. The system of claim 22 , wherein the predefined relationship is a linear relationship between the selected percentage of time and the total current demand over a range of the total current demand.