Method and System for Improving Processing Performance by Using Activity Factor Headroom

• US 20080082844A1
• Filed: 10/03/2006
• Published: 04/03/2008
• Est. Priority Date: 10/03/2006
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Rawson, Freeman Leigh, Ghiasi, Soraya, Rajamani, Karthick, Rubio, Juan C., Keller, Thomas Walter
• Granted Patent: US 7,681,054 B2
• Time in Patent Office: Days
• US Class Current: 713/323
• CPC Class Codes: G06F 1/3203 Power management, i.e. event-based initiation of a power-saving mode
• CPC Class Codes: G06F 1/329 by task scheduling
• CPC Class Codes: G06F 11/3466 Performance evaluation by tracing or monitoring
• CPC Class Codes: G06F 2201/88 Monitoring involving counting
• CPC Class Codes: Y02D 10/00 Energy efficient computing, e.g. low power processors, power management or thermal management

Abstract

A method and system for improving processing performance by using activity factor headroom provides improved performance while meeting power management constraints in a processing system. The method and system estimate the power consumption of the system from a model that relates measured activities at a present operating point to power consumption for any available operating point of one or more processors in the system. The method then chooses the operating point(s) with the highest performance among the available operating points that will still meet budgetary constraints or specific thresholds of power consumption. The budgetary constraints or specific thresholds may be dynamically adjusted, and the method will update the operating point(s) to maintain safe operation and maximize performance. The method provides the best performance for the executing workload while ensuring safe operation.

Claims

1. A method of controlling power consumption in a processing system, said method comprising:

measuring an activity level within a processor of said processing system, wherein said processor operates at one of multiple selectable operating points corresponding to differing levels of power consumption;

predicting a power consumption level of said processor for an operating point other than a present operating point of said processor, in conformity with said activity level and a presently selected operating point of said processor;

determining whether or not said predicted power consumption of said processor would yield a power consumption higher than a threshold if at least one other operating point were selected; and

in response to determining that said processor would not yield a power consumption higher than said threshold if said at least one other operating point were selected, selecting said at least one other operating point as an operating point of said processor.

2. The method of claim 1, further comprising modifying said threshold and re-evaluating a result of said selecting in conformity with said modified threshold.

3. The method of claim 1, wherein said measuring is performed by event counters that indicate a usage of multiple functional units within said processor.

4. The method of claim 3, wherein said method further comprises:

dynamically measuring actual power consumption of said processor at intervals of operation of said processing system;

observing a relationship between changes in said actual power consumption and values of said set of event counters; and

selecting said set of said set of event counters in conformity with said observed relationship, whereby said set of event counters is selected as those event counters having count values most sensitive to changes in said actual power consumption, and wherein subsequent repetitions of said measuring perform said measuring with said set of event counters.

5. The method of claim 3, wherein said method further comprises:

dynamically measuring actual power consumption of said processor at intervals of operation of said processing system;

observing a relationship between changes in said actual power consumption and values of said set of event counters; and

revising a model relating predicted power consumption and said values of said set of event counters in conformity with a result of said observing.

6. The method of claim 1, further comprising prior to said predicting, determining whether or not a present power consumption of said processor said is less than said threshold, and wherein said predicting, determining and selecting are performed in response to determining that said present power consumption of said processor is less than said threshold.

7. A system, comprising at one or more processors coupled to at least one memory for storing program instructions for execution by said one or more processors for performing power management, wherein said program instructions comprise program instructions for:

retrieving an activity level from a processor within said processing system, wherein said processor operates at multiple selectable operating points corresponding to differing levels of power consumption, and wherein said activity level is measured within said processor;

predicting a power consumption level of said processor for an operating point other than a present operating point of said processor, in conformity with said activity level and a presently selected operating point of said processor;

determining whether or not said predicted power consumption of said processor would yield a power consumption higher than a threshold if said at least one other operating point were selected; and

in response to determining that said processor would not yield a power consumption higher than said threshold if said at least one other operating point were selected, selecting said at least one other operating point as an operating point of said processor.

8. The system of claim 7, further comprising program instructions for modifying said threshold and re-evaluating a result of said selecting in conformity with said modified threshold.

9. The system of claim 7, wherein said program instructions for retrieving retrieve counts accumulated by a set of event counters that indicate a usage of multiple functional units within said processor.

10. The system of claim 9, wherein said program instructions further comprise program instructions for:

dynamically measuring actual power consumption of said processor at intervals of operation of said processing system;

observing a relationship between changes in said actual power consumption and values of said set of event counters; and

selecting said set of said set of event counters in conformity with said observed relationship, whereby said set of event counters is selected as those event counters having count values most sensitive to changes in said actual power consumption.

11. The system of claim 9, wherein said program instructions further comprise program instructions for:

dynamically measuring actual power consumption of said processor at intervals of operation of said processing system;

observing a relationship between changes in said actual power consumption and values of said set of event counters; and

revising a model relating predicted power consumption and said values of said set of event counters in conformity with a result of said observing.

12. The system of claim 7, wherein said program instructions further comprise program instructions for execution prior to execution of said program instructions for predicting, that determine whether or not a present power consumption of said processor is less than said threshold, and wherein said program instructions for predicting, determining and selecting are executed only in response to determining that said estimated power consumption of said processor is less than said threshold.

13. A computer program product comprising storage media containing program instructions for execution by a processor for performing power management, said program instructions comprising program instructions for:

retrieving an activity level from a processor within said processing system, wherein said processor operates at multiple selectable operating points corresponding to differing levels of power consumption, and wherein said activity level is measured within said processor;

predicting a power consumption level of said processor for an operating point other than a present operating point of said processor, in conformity with said activity level and a presently selected operating point of said processor;

determining whether or not said predicted power consumption of said processor would yield a power consumption higher than a threshold limit if said at least one other operating point were selected; and

in response to determining that said processor would not yield a power consumption higher than said threshold if said at least one other operating point were selected, selecting said at least one other operating point as an operating point of said processor.

14. The computer program product of claim 13, wherein said program instructions for retrieving retrieve counts from a set of event counters within said processor, and wherein said program instructions further comprise program instructions for:

dynamically measuring actual power consumption of said processor at intervals of operation of said processing system;

observing a relationship between changes in said actual power consumption and values of said set of event counters; and

selecting said set of event counters in conformity with said observed relationship, whereby said set of event counters is selected as those event counters reflective of greatest changes in said actual power consumption.

15. The computer program product of claim 13, wherein said program instructions for retrieving retrieve counts from a set of event counters within said processor, and wherein said program instructions further comprise program instructions for:

dynamically measuring actual power consumption of said processor at intervals of operation of said processing system;

observing a relationship between changes in said actual power consumption and values of said set of event counters; and

revising a model relating predicted power consumption and said values of said set of event counters in conformity with a result of said observing.

16. A processor integrated on a semiconductor die, comprising:

an activity measurement unit for measuring a usage of resources within said processor at a present frequency and voltage operating point for a present workload;

control logic for receiving an indication of an activity level from said activity measurement unit and estimating a power consumption level for said present workload at another frequency and voltage operating point selectable for said processor, wherein said control logic determines whether or not said estimated power consumption level is less than a threshold, and responsive to determining that said estimated power consumption level is less than said threshold, automatically selects said other operating point.

17. The processor of claim 16, wherein said activity measurement unit comprises a counter for counting instruction dispatches within said processor.

18. The processor of claim 16, wherein said activity measurement unit comprises a set of event counters that indicate a usage of multiple functional units within said processor.

19. The processor of claim 18, further comprising a power measurement unit for dynamically measuring actual power consumption of said processor at intervals of operation of said processor, and wherein said control logic determines a relationship between changes in said actual power consumption and values of said set of event counters and selects said set of said set of event counters in conformity with said observed relationship, whereby said set of event counters is selected as those event counters reflective of greatest changes in said actual power consumption.

20. The processor of claim 16, wherein said control logic detects a change of said threshold and repeats said selecting in response to said detected change.