Data flow control system and method for conserving power in a power managed system

• US 7,421,591 B2
• Filed: 08/29/2003
• Issued: 09/02/2008
• Est. Priority Date: 08/29/2003
• Status: Active Grant

• Current Assignee: Dell Products LP (Dell Technologies Inc.)
• Original Assignee: Dell Products LP (Dell Technologies Inc.)
• Inventors: Sultenfuss, Andrew T., Lewis, Jonathan Foster
• Primary Examiner(s): Patel; Nitin C.
• Assistant Examiner(s): Rahman; Fahmida
• Application Number:
  US10/651,946
• Publication Number:
  US 20050057954A1
• Time in Patent Office: 1,831 Days
• Field of Search: 713/300, 713/310, 713320-324, 713/330, 713/340, 365/129
• US Class Current: 713/300
• CPC Class Codes: G06F 1/3203 Power management, i.e. event-based initiation of a power-saving mode
• CPC Class Codes: G06F 1/3228 Monitoring task completion, e.g. by use of idle timers, stop commands or wait commands
• CPC Class Codes: G06F 1/329 by task scheduling
• CPC Class Codes: G11C 5/14 Power supply arrangements , e.g. power down, chip selection or deselection, layout of wirings or power grids, or multiple supply levels
• CPC Class Codes: Y02D 10/00 Energy efficient computing, e.g. low power processors, power management or thermal management

Abstract

A system and method for conserving power in a power managed information handling system are provided. While the host unit or central processing unit of the information handling system is in a reduced power state, the communication controller maintains received data in an associated buffer. The communication controller releases all or a portion of the buffered data during time intervals in which the host unit is in a normal operating mode. By buffering and releasing data in coordination with the reduced power state and normal operating state, respectively, of the host unit, power conservation in the information handling system may be enhanced by not causing the host unit to return to normal operation prematurely.

Claims

1. A method for conserving power in an information handling system, comprising:

while a host unit is in a normal power state, evaluating activity criteria from time to time, wherein said activity criteria are indicative of activity on a bus of the host unit;

evaluating said activity criteria to determine whether one or more pending activities should be completed to fulfill the needs of a currently running process;

responsive to determining the one or more pending activities should be completed, maintaining the host unit in the normal power state until the one or more pending activities is completed;

responsive to said activity criteria indicating both a lack of current bus activity and a lack of the one or more pending activities that should be completed, transitioning the host unit to a reduced power state;

responsive to receiving data by a communication controller while said host unit is in said reduced power state, maintaining the data in a buffer associated with the communication controller; and

releasing the data from the buffer for processing responsive to the host unit transitioning from the reduced power state to the normal power state.

2. The method of claim 1, further comprising:

while the host unit is in the reduced power state, evaluating buffered data criteria from time to time, wherein said buffered data criteria are indicative of a volume or priority of said data in said buffer;

responsive to said buffered data criteria indicating said data in said buffer has a predetermined priority or indicating a risk of data loss, transitioning the host unit to the normal power state, and releasing the data from the buffer for processing.

3. The method of claim 2, further comprising determining whether the bus of the host unit is active between releases of the data.

4. The method of claim 1, further comprising:

releasing the data for processing during a first fixed time interval; and

holding the data for a second fixed time interval.

5. The method of claim 4, further comprising varying the selected intervals in accordance with data volumes received by the communication controller.

6. The method of claim 1, further comprising monitoring buffer data volume to identify potential buffer data overflows.

7. The method of claim 6, further comprising emerging the host unit from the reduced power state in response to the identification of a potential buffer data overflow.

8. The method of claim 1, further comprising:

parsing received data to identify priority data; and

queuing the priority data for priority processing.

9. The method of claim 8, further comprising releasing the priority data from the buffer for substantially immediate processing.

10. A method for reducing power consumption in an information handling system, comprising:

evaluating activity criteria indicative of activity on one or more data buses coupled to a host unit of the information handling system to determine whether one or more pending activities should be completed to fulfill the needs of a process currently running on the host unit;

responsive to determining that the one or more pending activities should be completed, maintaining the one or more data buses in normal state until the one or more pending activities is completed;

quieting the one or more data buses;

migrating the host unit to a reduced power state upon quieting the one or more data buses;

maintaining the host unit in the reduced power state and the one or more data buses quiet for a selected period of time; and

resuming operation of the information handling system in accordance with a user selected operating mode after the selected period of time has elapsed.

11. The method of claim 10, further comprising buffering data received during the reduced power state period by an information handling system communication controller.

12. The method of claim 11, further comprising monitoring the information handling system communication controller for potential data overflow resulting from buffering the received data.

13. The method of claim 11, further comprising identifying buffered packets for priority processing upon resuming operation of the information handling system in accordance with the user selected operating mode.

14. An information handling system capable of existing in a reduced power state and a normal power state, comprising:

a host unit;

a data bus operably coupled to the host unit;

a communication controller operably coupled to the data bus and the host unit, the communication controller having a memory and operable to receive a volume of data;

the information handling system being enabled, while the host unit is in the normal power state, to evaluate activity criteria from time to time, wherein said activity criteria are indicative of activity on the data bus;

the information handling system being further enabled to evaluate said activity criteria to determine whether one or more pending activities should be completed to fulfill the needs of a currently running process;

the information handling system being further enabled, responsive to determining the one or more pending activities should be completed, to maintain the host unit in the normal power state until the one or more pending activities is completed;

the information handling system being further enabled, responsive to said activity criteria indicating both a lack of current bus activity and a lack of the one or more pending activities that should be completed, to transition the host unit to the reduced power state; and

the communication controller being operable to maintain received data in said memory while said host unit is in said reduced power state.

15. The system of claim 14, further comprising the communication controller operable to delay the release of the data in anticipation of transition of the host unit to the reduced power state.

16. The system of claim 14, further comprising the communication controller operable to parse the data received to identify priority data and release the priority data for processing whether the host unit is in the reduced power state or the normal power state.

17. The system of claim 14, further comprising the communication controller operable to influence time spent by the host unit in the normal power state and the reduced power state by varying its release of the data in accordance with at least one characteristic of data flow.

18. The system of claim 14, further comprising:

a first time interval associated with the reduced power state of the host unit;

a second time interval associated with the normal power state of the host unit; and

the communication controller operable to adapt its holding of the received data to correspond to the first time interval and its release of the data to correspond to the second time interval.

19. The system of claim 14, further comprising the communication controller operable to monitor the memory for data overflow and release the data from memory for processing in response to detection of data loss.

20. The system of claim 14, further comprising the communication controller operable to determine host unit operation status by monitoring activity on the data bus.