Power state resynchronization

• US 6,795,927 B1
• Filed: 07/17/2001
• Issued: 09/21/2004
• Est. Priority Date: 05/01/2001
• Status: Active Grant

• Current Assignee: MediaTek, Inc.
• Original Assignee: Advanced Micro Devices, Inc.
• Inventors: Menezes, Evandro, Altmejd, Morrie, Russell, Richard, Tobias, David F.
• Primary Examiner(s): Butler, Dennis M.
• Assistant Examiner(s): Suryawanshi, Suresh K
• Application Number:
  US09/907,083
• Time in Patent Office: 1,162 Days
• Field of Search: 713/300, 713/310, 713/320, 713/324, 713/340, 713/323, 713/330, 713/322
• US Class Current: 713/300
• CPC Class Codes: G06F 1/3203 Power management, i.e. event-based initiation of a power-saving mode

Abstract

A computer system has multiple performance states. The computer system periodically determines if the software power state maintained by power management software that represents the power state of the processor or other computer system component matches the actual power state of the processor or other computer system component. If not, the actual power state and the software power state are resynchronized, for example, by reinitializing the power management software or otherwise causing the software power state to match the hardware power state.

Claims

1. A method of managing power in a computing system comprising:

periodically determining a current hardware power state of an integrated circuit;

periodically comparing the current hardware power state to a software power state maintained by power management software, the software state representing an assumed power state of the integrated circuit; and

resynchronizing at least one of the hardware power state and the software power state if a discrepancy exists between the hardware power state and the software power state.

2. The method as recited in claim 1 wherein the resynchronizing includes reinitializing the power management software maintaining the software power state.

3. The method as recited in claim 1 wherein the resynchronizing includes changing the software power state to match the hardware power state.

4. The method as recited in claim 1 wherein the resynchronizing includes changing the hardware power state to match the software power state.

5. The method as recited in claim 1 wherein the hardware power state is a performance state corresponding to an operating voltage and clock frequency of the integrated circuit.

6. The method as recited in claim 1 wherein the software power state indicates one of a plurality of possible performance states, each performance state being a unique combination of operating voltage and frequency of the integrated circuit.

7. A computer system comprising:

an integrated circuit;

a first instruction sequence operable on the integrated circuit to periodically determine a current hardware power state of the integrated circuit;

a second instruction sequence operable on the integrated circuit to periodically compare the current hardware power state to a software maintained power state, the software maintained power state indicating a power state assumed by power management software, the second instruction sequence operable to generate an indication of the comparison; and

a third instruction sequence operable on the integrated circuit to resynchronize at least one of the hardware power state and the software maintained power state if a discrepancy exists between the hardware power state and the software maintained power state.

8. The computer system as recited in claim 7 wherein integrated circuit includes a processor.

9. The computer system as recited in claim 7 wherein the resynchronizing includes reinitializing the power management software maintaining the software maintained power state.

10. The computer system as recited in claim 7 wherein the software maintained power state indicates one of a plurality of possible performance states, each performance state being a unique combination of operating voltage and frequency.

11. A computer program product encoded in at least one computer readable medium to implement power management, the computer program product operable to:

periodically determine an actual performance state of an integrated circuit;

periodically compare the actual performance state to a software maintained performance state and generate an indication of the comparison; and

resynchronize the actual performance state and the software maintained performance state if the indication indicates that a discrepancy exists between the actual performance state and the software maintained performance state.

12. The computer program product as recited in claim 11 wherein the actual performance state and the software maintained performance state are resynchronized by reinitializing power management software maintaining the software maintained performance state.

13. The computer program product as recited in claim 11 wherein the actual performance state and the software maintained performance state are resynchronized by changing the software maintained performance state to match the actual performance state.

14. The computer program product as recited in claim 11 wherein the actual performance state and the software maintained performance state are resynchronized by changing the actual performance state to match the software maintained performance state.

15. The computer program product as recited in claim 11 wherein the at least one computer readable medium is selected from the set of a disk, tape or other magnetic, optical, or electronic storage medium and a network, wireline, wireless or other communications medium.

16. A computing system comprising:

an integrated circuit having multiple operational performance states;

means for periodically determining an actual performance state of the integrated circuit;

means for periodically comparing the actual performance state to a power management software performance state representing an assumed performance state and for generating an indication of the comparison; and

means for resynchronizing the actual performance state and the power management software performance state if the indication indicates that a discrepancy exists between the actual performance state and the power management software performance state.

17. The computing system as recited in claim 16 wherein the actual performance state and the power management software performance state are resynchronized by changing the power management software performance state to match the actual performance state.

18. The computing system as recited in claim 16 wherein the actual performance state and the power management software performance state are resynchronized by changing the actual performance state to match the power management software performance state.

19. The computing system as recited in claim 16 wherein the actual performance state and the power management software performance state are resynchronized by reinitializing the power management software maintaining the power management software performance state and thereby changing the actual performance state to a maximum performance state.