Computer System Power Management Based on Task Criticality

• US 20100185882A1
• Filed: 01/16/2009
• Published: 07/22/2010
• Est. Priority Date: 01/16/2009
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Olson, Gregory A., Arnold, Jeremy A., Stec, Eric J., Moore, Scott A.
• Granted Patent: US 8,140,876 B2
• Time in Patent Office: Days
• US Class Current: 713/320
• CPC Class Codes: G06F 1/3203 Power management, i.e. event-based initiation of a power-saving mode
• CPC Class Codes: G06F 1/3287 by switching off individual functional units in the computer system
• CPC Class Codes: G06F 1/329 by task scheduling
• CPC Class Codes: G06F 9/4893 taking into account power or heat criteria power management in computers in general G06F1/3203; thermal management in computers in general G06F1/206
• CPC Class Codes: Y02D 10/00 Energy efficient computing, e.g. low power processors, power management or thermal management

Abstract

A method, apparatus, and program product are provided for managing power consumption in a computer system based on the degree with which performance of tasks can be degraded in order to save power. A criticality value controls the degree with which performance of a task may be degraded is associated with tasks within a computer system. Power consumption of the computer system is then managed based on the criticality values associated with tasks executing within the computer system. A reduction in computer system power consumption can be realized by degrading the performance of non-critical tasks, which is accomplished by reducing the power consumed by at least a portion of the computer system. Power can also be reduced by scheduling non-critical tasks to portions of the computer system and reducing power consumption of other portions of the computer system.

Claims

1. A method of managing power consumption in a computer system, the method comprising:

associating with each of a plurality of tasks executing in the computer system a criticality value, the criticality value controlling a degree with which a performance of the task can be degraded in order to reduce power consumption in the computer system; and

managing power consumption in the computer system based on the criticality values associated with at least a subset of the tasks executing in the computer system, including reducing power consumption of at least a portion of the computer system during execution of a first task among the plurality of tasks based at least in part on the criticality value associated with the first task such that performance of the first task is degraded.

2. The method of claim 1 wherein managing power consumption further includes degrading performance of the first task, wherein performance of the first task is degraded by using an operation selected from a group consisting of:

pausing the first task, executing the first task at a slower speed, stopping the first task, executing the first task using resources being shared by other tasks, and combinations thereof.

3. The method of claim 1 wherein the criticality values of the first task and a second task executing in the computer system each indicate a non-critical status, and wherein managing power consumption includes, based upon the criticality values of the first and second tasks indicating the non-critical status:

scheduling the first and second tasks to execute on a first portion of the computer system; and

reducing power consumption of a second, unused portion of the computer system.

4. The method of claim 1 further comprising:

associating a priority value with each of the plurality of tasks such that each task is associated with both a priority value and a criticality value.

5. The method of claim 4 wherein the criticality value of the first task is based at least in part on the priority value of the first task.

6. The method of claim 4 wherein the first task has a high priority value and a low criticality value.

7. The method of claim 4 wherein a second task among the plurality of tasks has a low priority value and a high criticality value.

8. The method of claim 1 further comprising changing the criticality value of the first task during the execution of the first task.

9. The method of claim 1 wherein managing power consumption further includes accessing a power management policy to determine whether to reduce power consumption in the portion of the computer system.

10. The method of claim 9 wherein the power management policy dictates reducing power consumption by performing an operation selected from the group consisting of:

reducing a clock rate of at least a portion of the computer system, reducing a voltage of at least a portion of the computer system, partially or completely shutting down at least a portion of the computer system, and combinations thereof.

11. The method of claim 9 wherein the first task is selected from the group consisting of a process and a thread.

12. The method of claim 1 wherein associating criticality values with the plurality of tasks includes associating an indicator with the criticality value of each task of the plurality of tasks, and wherein managing power consumption includes:

accessing the indicator for the first task to determine if the performance of the first task can be degraded.

13. The method of claim 12 wherein the indicator comprises a binary flag representing either a critical or non-critical status.

14. The method of claim 12 wherein the indicator comprises a flag containing multiple bits defining a range for the criticality value.

15. The method of claim 1 wherein the first task comprises a process, wherein the process includes at least one thread, and wherein a criticality value of the thread is inherited from the process.

16. An apparatus comprising:

a processor; and

program code configured to be executed by the processor to manage power consumption in a computer system, the program code configured to associate with each of a plurality of tasks executing in the computer system a criticality value, the criticality value controlling a degree with which a performance of the task can be degraded in order to reduce power consumption in the computer system, and manage power consumption in the computer system based on the criticality values associated with at least a subset of the tasks executing in the computer system, including reducing power consumption of at least a portion of the computer system during execution of a first task among the plurality of tasks based at least in part on the criticality value associated with the first task such that performance of the first task is degraded.

17. The apparatus of claim 16 wherein the program code configured to manage power consumption is further configured to degrade performance of the first task, wherein performance of the first task is degraded by using an operation selected from a group consisting of:

pausing the first task, executing the first task at a slower speed, stopping the first task, executing the first task using resources being shared by other tasks, and combinations thereof.

18. The apparatus of claim 16 wherein the criticality values of the first task and a second task executing in the computer system each indicate a non-critical status, and wherein the program code configured to manage power consumption is further configured to, based upon the criticality values of the first and second tasks indicating the non-critical status:

schedule the first and second tasks to execute on a first portion of the computer system; and

reduce power consumption of a second, unused portion of the computer system.

19. The apparatus of claim 16 wherein the program code is further configured to:

associate a priority value with each of the plurality of tasks such that each task is associated with both a priority value and a criticality value.

20. The apparatus of claim 16 wherein the program code configured to associate criticality values with the plurality of tasks is further configured to associate an indicator with the criticality value of each task of the plurality of tasks, and wherein the program code configured to manage power consumption is further configured to:

access the indicator for the first task to determine if the performance of the first task can be degraded.

21. The apparatus of claim 16 wherein the first task comprises a process, wherein a criticality value of the process is inherited from a parent of the process.

22. A program product, comprising:

a computer readable medium; and

a program code configured to manage power consumption in a computer system, the program code resident on the computer readable medium and configured to associate with each of a plurality of tasks executing in the computer system a criticality value, the criticality value controlling a degree with which a performance of the task can be degraded in order to reduce power consumption in the computer system, and manage power consumption in the computer system based on the criticality values associated with at least a subset of the tasks executing in the computer system, including reducing power consumption of at least a portion of the computer system during execution of a first task among the plurality of tasks based at least in part on the criticality value associated with the first task such that performance of the first task is degraded.

23. A method of managing power consumption in a multicore computer system comprising a plurality of processing cores, the method comprising:

associating with each of a plurality of tasks executing in the computer system a criticality value, the criticality value of each task controlling a degree with which a performance of the associated task can be degraded in order to reduce power consumption in the computer system; and

managing power consumption in the multicore computer system based on the criticality values associated with at least a subset of the tasks executing in the multicore computer system, including reducing power consumption of a first subset of processing cores among the plurality of processing cores in the computer system relative to a second subset of processing cores among the plurality of processing cores and scheduling a first task among the plurality of tasks to execute on a processing core from one of the first and second subsets of processing cores based at least in part on the criticality value associated with the first task.

24. The method of claim 23, wherein managing power consumption includes:

scheduling each task from among the plurality of tasks that is associated with a low criticality value to execute on a processing core from the first subset of processing cores; and

scheduling each task from among the plurality of tasks that is associated with a high criticality value to execute on a processing core from the second subset of processing cores.

25. The method of claim 23, wherein managing power consumption includes, in response to determining that only tasks associated with a low criticality value are executing on the multicore computer system:

scheduling each task to execute on a processing core from a third subset of processing cores; and

configuring at least one processing core from a fourth subset of processing cores to enter a low power state.