Power state coordination between devices sharing power-managed resources

• US 20050273635A1
• Filed: 06/17/2004
• Published: 12/08/2005
• Est. Priority Date: 06/02/2004
• Status: Active Grant

• Current Assignee: Tahoe Research Limited (f/k/a Learndale Limited) (Vector Capital Corporation)
• Original Assignee: Intel Corporation
• Inventors: Hacking, Lance E., Gunther, Stephen H., Wilcox, Jeffrey R., Bodas, Devadatta V., Kaushik, Shivnandan, Poisner, David, Ramakrishnan, Siva
• Granted Patent: US 7,315,952 B2
• Time in Patent Office: Days
• US Class Current: 713/320
• CPC Class Codes: G06F 1/26 Power supply means, e.g. regulation thereof for memories G11C
• CPC Class Codes: G06F 1/3203 Power management, i.e. event-based initiation of a power-saving mode
• CPC Class Codes: G06F 1/3246 by software initiated power-off
• CPC Class Codes: G06F 1/3287 by switching off individual functional units in the computer system
• CPC Class Codes: Y02D 10/00 Energy efficient computing, e.g. low power processors, power management or thermal management

Abstract

Methods and apparatuses for coordination of power state management in and electronic system.

Claims

1. A method comprising:

transmitting a message indicating a potential change of operational state for a primary device in an electronic system;

receiving one or more responses to the message from one or more respective secondary devices coupled with the primary device indicating allowable operational states of the primary device indicated by the one or more secondary devices; and

transitioning the primary device to an operational state determined based on the responses received from the secondary devices.

2. The method of claim 1 further comprising initiating an alternative operational state transition in the primary device if one or more of the responses indicate that the alternative power state transition is permitted, the alternative power state transition being based on a performance requirement of at least one of the secondary devices.

3. The method of claim 1 wherein transmitting the message indicating the potential change of operational state for the primary device comprises:

receiving notification of a pending power state transition; and

using coordination agent to generate a message to be transmitted to one or more secondary devices to determine whether the power state transition in a primary device is permitted by the one or more secondary devices, the primary device sharing a resource with the set of secondary devices.

4. The method of claim 1 wherein transitioning the primary device to an operational state determined based on the responses received from the secondary devices comprises:

comparing a target power state for the primary device to one or more allowable power states for the primary device as indicated by the responses received from the secondary devices; and

causing the primary device to transition to one of the target power state and the one or more allowable power states.

5. The method of claim 4 wherein causing the primary device to transition to one of the target power state and the one or more allowable power states comprises causing the primary power state to transition to a highest power state from the target power state and the one or more allowable power states.

6. The method of claim 4 wherein causing the primary device to transition to one of the target power state and the one or more allowable power states comprises causing the primary power state to transition to a lowest power state from the target power state and the one or more allowable power states.

7. The method of claim 1 wherein the operational state comprises a power state.

8. The method of claim 1 wherein the operational state comprises a perfomance state.

9. The method of claim 1 further comprising:

transmitting a subsequent message indicating a potential change of operational state for the primary device;

indicating the subsequent message as a retry message;

receiving one or more subsequent responses to the subsequent message from one or more respective secondary devices coupled with the primary device indicating allowable operational states of the primary device indicated by the one or more secondary devices; and

transitioning the primary device to a subsequent operational state determined based on the subsequent responses received from the secondary devices.

10. The method of claim 1 further comprising:

transmitting a message indicating a potential change of operational state for one of the secondary devices;

indicating the subsequent message as a retry message; and

transitioning the primary device to a selected operational state determined based on responses received from the secondary devices.

11. The method of claim 1 further comprising:

transmitting a message indicating a potential change of operational state for a selected one of the secondary devices;

indicating the subsequent message as a retry message; and

transitioning the selected secondary device to an operational state determined based on responses received from the other secondary devices.

18. The apparatus of claim 11 wherein the coordination agent comprises circuitry in an electronic system.

19. The apparatus of claim 11 wherein the coordination agent comprises circuitry configured to communicate with multiple devices configured as a network of wireless devices.

20. The apparatus of claim 11 wherein the coordination agent causes the primary device to transition to a highest power state from a target power state as indicated by the message and one or more allowable power states as indicated by the responses.

21. The apparatus of claim 11 wherein the coordination agent causes the primary device to transition to a lowest power state from a target power state as indicated by the message and one or more allowable power states as indicated by the responses.

12. An apparatus comprising:

a primary device having a resource to be shared with one or more secondary devices coupled with the primary device; and

a coordination agent coupled with the primary device and the one or more secondary devices to transmit a message indicating a potential change of operational state for a primary device to the one or more secondary devices and to cause the primary device to transition to an operational state determined based on responses received from the secondary devices.

13. The apparatus of claim 12, wherein the coordination agent receives notification of a power state transition, identifies secondary devices as being dependent on a power state transition, sends the message to the secondary devices, receives the responses from the secondary devices.

14. The apparatus of claim 12, wherein the primary device comprises a processor, the resource comprises a cache memory, and at least one of the secondary devices comprises a processor.

15. The apparatus of claim 12, wherein the coordination agent is coupled to access at least one of an explicit and an implicit dependencies list to identify secondary devices as being dependent on a power state transition, the dependencies list to be dedicated to the primary device.

16. The apparatus of claim 12 wherein the operational state comprises a power state.

17. The apparatus of claim 12 wherein the operational state comprises a performance state.

22. A system comprising:

a digital signal processor;

a primary device coupled with the digital signal processor having a resource to be shared with one or more secondary devices coupled with the primary device; and

a coordination agent coupled with the primary device and the one or more secondary devices to transmit a message indicating a potential change of operational state for a primary device to the one or more secondary devices and to cause the primary device to transition to an operational state determined based on responses received from the secondary devices.

23. The system of claim 22, wherein the coordination agent receives notification of a power state transition, identifies secondary devices as being dependent on a power state transition, sends the message to the secondary devices, receives the responses from the secondary devices.

24. The system of claim 22, wherein the primary device comprises a processor, the resource comprises a cache memory, and at least one of the secondary devices comprises a processor.

25. The system of claim 22, wherein the coordination agent is coupled to access at least one of an explicit and an implicit dependencies list to identify secondary devices as being dependent on a power state transition, the dependencies list to be dedicated to the primary device.

26. The system of claim 22 wherein the operational state comprises a power state.

27. The system of claim 22 wherein the operational state comprises a performance state.

28. The system of claim 22 wherein the coordination agent comprises circuitry in an electronic system.

29. The system of claim 22 wherein the coordination agent causes the primary device to transition to a highest power state from a target power state as indicated by the message and one or more allowable power states as indicated by the responses.

30. The system of claim 22 wherein the coordination agent causes the primary device to transition to a lowest power state from a target power state as indicated by the message and one or more allowable power states as indicated by the responses.