DYNAMIC TECHNIQUES FOR OPTIMIZING SOFT REAL-TIME TASK PERFORMANCE IN VIRTUAL MACHINE

• US 20120216207A1
• Filed: 04/19/2012
• Published: 08/23/2012
• Est. Priority Date: 08/10/2009
• Status: Active Grant

• Current Assignee: Avaya Incorporated
• Original Assignee: Avaya Incorporated
• Inventors: Krishnakumar, Anjur Sundaresan, Krishnan, Parameshwaran, Lee, Min, Singh, Navjot, Yajnik, Shalini
• Granted Patent: US 8,499,303 B2
• Time in Patent Office: Days
• US Class Current: 718/103
• CPC Class Codes: G06F 9/4881 Scheduling strategies for dispatcher, e.g. round robin, multi-level priority queues

Abstract

Methods to dynamically improve soft real-time task performance in virtualized computing environments under the management of an enhanced hypervisor comprising a credit scheduler. The enhanced hypervisor analyzes the on-going performance of the domains of interest and of the virtualized data-processing system. Based on the performance metrics disclosed herein, some of the governing parameters of the credit scheduler are adjusted. Adjustments are typically performed cyclically, wherein the performance metrics of an execution cycle are analyzed and adjustments may be applied in a later execution cycle. In alternative embodiments, some of the analysis and tuning functions are in a separate application that resides outside the hypervisor. The performance metrics disclosed herein include: a “total-time” metric; a “timeslice” metric; a number of “latency” metrics; and a “count” metric. In contrast to prior art, the present invention enables on-going monitoring of a virtualized data-processing system accompanied by dynamic adjustments based on objective metrics.

Claims

1. A method comprising:

receiving by a hypervisor in a data-processing system a first metric that is associated with a first domain, wherein;

(i) the data-processing system comprises a first processor and a second processor,

(ii) the first domain comprises a first plurality of tasks that were executed on the data-processing system, and

(iii) the first metric is based on the amount of time, during an earlier time interval, that was spent executing tasks of the first domain that had an over priority;

when the value of the first metric is above a first threshold, increasing an amount of time to be spent in a later time interval to execute tasks of the first domain that have an over priority; and

executing by the data-processing system in the later time interval the tasks of the first domain, based on the increased amount of time.

2. The method of claim 1 wherein:

the increasing is further based on a second metric that is based on a measurement of total latency, during the earlier time interval, of tasks of the first domain that had an over priority.

3. The method of claim 1 further comprising:

receiving by the hypervisor a second metric that is based on the amount of time, during the earlier time interval, that was spent executing tasks of the first domain that had an under priority; and

when the value of the second metric is below a second threshold;

(i) scheduling exclusively to the first processor the tasks of the first domain, to be executed in the later time interval, and

(ii) scheduling the tasks of a second domain, to be executed in the later time interval, to a processor in the data-processing system that is exclusive of the first processor.

4. The method of claim 1 wherein the hypervisor comprises a credit-scheduler that performs the increasing.

5. The method of claim 1 wherein an application transmits at least one instruction to the hypervisor to perform the increasing, and wherein the application is separate from the hypervisor.

6. The method of claim 5 wherein the increasing is based on a weight that is generated by the application.

7. The method of claim 1 wherein the first domain is a time-sensitive domain.

8. The method of claim 1 wherein some of the first plurality of tasks are time-sensitive tasks.

9. The method of claim 1 further comprising:

when an event arrives that is associated with a task that is time-sensitive, assign a boost priority to the task, wherein the assigning is independent of the pre-existing priority of the task, and wherein the task is to be executed on the data-processing system in the later time interval in accordance with the boost priority.

10. The method of claim 1 further comprising:

receiving, by the data-processing system, a second metric that is associated with the first domain, wherein the second metric is based on the amount of time, during the earlier time interval, that was spent executing tasks of the first domain that had an under priority;

receiving, by the data-processing system, a third metric that is associated with a second domain, wherein;

(i) the second domain comprises a second plurality of tasks that were executed on the data-processing system, and

(ii) the third metric is based on the amount of time, during the earlier time interval, that was spent executing tasks of the second domain that had an under priority;

when the value of the second metric is below a second threshold and the value of the third metric is below a third threshold, bin-packing by the hypervisor the first plurality of tasks and the second plurality of tasks into at least a first bin-pack, wherein the bin-packing is based on minimizing the number of processors that are to execute the first plurality of tasks and the second plurality of tasks; and

executing by the first processor the tasks in the first bin-pack.

11. A method comprising:

receiving, by a hypervisor in a data-processing system, a first metric that is associated with a first domain, wherein;

(i) the data-processing system comprises a first processor and a second processor,

(ii) the first domain comprises a first plurality of tasks that were executed on the data-processing system, and

(iii) the first metric is based on the amount of time, during an earlier time interval, that was spent executing tasks of the first domain that had an under priority; and

when the value of the first metric is below a first threshold, scheduling the tasks of the first domain exclusively to the first processor, to be executed in a later time interval; and

executing, in the later time interval, exclusively by the first processor, the tasks of the first domain.

12. The method of claim 11 further comprising:

when the value of the first metric is below a first threshold, scheduling the tasks of a second domain to a processor in the data-processing system that is exclusive of the first processor, to be executed in the later time interval.

13. The method of claim 11 wherein the hypervisor comprises a credit-scheduler that performs the increasing.

14. The method of claim 11 wherein the first domain is a time-sensitive domain.

15. The method of claim 11 wherein some of the first plurality of tasks are time-sensitive tasks.

16. The method of claim 11 further comprising:

when an event arrives that is associated with a task that is time-sensitive, assign a boost priority to the task, wherein the assigning is independent of the pre-existing priority of the task, and wherein the task is to be executed on the data-processing system in the later time interval in accordance with the boost priority.

17. A method comprising:

receiving by a hypervisor in a data-processing system a first metric that is associated with a first domain, wherein;

(i) the data-processing system comprises a first processor and a second processor,

(ii) the first domain comprises a first plurality of tasks that were executed on the data-processing system, and

(iii) the first metric is based on a measurement of total latency, during an earlier time interval, of tasks of the first domain that had an over priority; and

when the value of the first metric is above a first threshold, increasing the amount of time to be spent in a later time interval to execute tasks of the first domain that have an over priority.

18. The method of claim 17 further comprising:

receiving by the data-processing system a second metric that is based on the amount of time, during the earlier time interval, that was spent executing tasks of the first domain that had an under priority; and

when the value of the second metric is below a second threshold;

(i) scheduling exclusively to the first processor the tasks of the first domain, to be executed in the later time interval, and

(ii) scheduling the tasks of a second domain, to be executed in the later time interval, to a processor in the data-processing system that is exclusive of the first processor.

19. The method of claim 17 wherein the hypervisor comprises a credit-scheduler that performs the increasing.

20. The method of claim 17 wherein an application transmits at least one instruction to the hypervisor to perform the increasing, and wherein the application is separate from the hypervisor, and wherein the increasing is based on a weight that is generated by the application.

21. The method of claim 17 wherein the first domain is a time-sensitive domain.

22. The method of claim 17 wherein some of the first plurality of tasks are time-sensitive tasks.

23. The method of claim 17 further comprising:

when an event arrives that is associated with a task that is time-sensitive, assign a boost priority to the task, wherein the assigning is independent of the pre-existing priority of the task, and wherein the task is to be executed on the data-processing system in the later time interval in accordance with the boost priority.

24. The method of claim 17 further comprising:

receiving, by the data-processing system, a second metric that is associated with the first domain, wherein the second metric is based on the amount of time, during the earlier time interval, that was spent executing tasks of the first domain that had an under priority;

receiving, by the data-processing system, a third metric that is associated with a second domain, wherein;

(i) the second domain comprises a second plurality of tasks that were executed on the data-processing system, and

(ii) the third metric is based on the amount of time, during the earlier time interval, that was spent executing tasks of the second domain that had an under priority;

when the value of the second metric is below a second threshold and the value of the third metric is below a third threshold, bin-packing by the hypervisor the first plurality of tasks and the second plurality of tasks into at least a first bin-pack, wherein the bin-packing is based on minimizing the number of processors that are to execute the first plurality of tasks and the second plurality of tasks; and

executing by the first processor the tasks in the first bin-pack.