Method and apparatus to control priority preemption of tasks

• US 20080052716A1
• Filed: 08/22/2006
• Published: 02/28/2008
• Est. Priority Date: 08/22/2006
• Status: Active Grant

• Current Assignee: LinkedIn Corporation (Microsoft Corporation)
• Original Assignee: International Business Machines Corporation
• Inventors: THEURER, ANDREW Matthew
• Granted Patent: US 7,844,970 B2
• Time in Patent Office: Days
• US Class Current: 718/103
• CPC Class Codes: G06F 9/4856 resumption being on a different machine, e.g. task migration, virtual machine migration G06F9/5088 takes precedence
• CPC Class Codes: G06F 9/4881 Scheduling strategies for dispatcher, e.g. round robin, multi-level priority queues

Abstract

A computer implemented method, apparatus, system, and computer usable program product for controlling preemption rates. A scheduler identifies a preemption interval in response to a plurality of processes being executed by a processor. Only a single preemption of a process occurs during the preemption interval. The scheduler preempts a currently running process only once during the preemption interval. The preemption interval is adjusted to increase performance in executing processes.

Claims

1. A computer implemented method for controlling preemption rates, the computer implemented method comprising:

responsive to a plurality of processes being executed by a processor, identifying a preemption interval, wherein only a single preemption of a process occurs during the preemption interval; and

preempting a currently running process only once during the preemption interval, wherein the preemption interval is adjusted to increase performance in executing processes.

2. The computer implemented method of claim 1 further comprising:

setting a preemption timer, wherein the preemption timer expires at the end of the preemption interval; and

responsive to a determination that the preemption interval has expired, performing a preemption of the currently running process.

3. The computer implemented method of claim 1 further comprising:

adjusting the preemption interval to form an updated preemption interval.

4. The computer implemented method of claim 1 further comprising:

responsive to performing a priority preemption, setting a last preemption time as a current time, wherein the last preemption time is a time at which the most recently performed priority preemption of a process took place.

5. The computer implemented method of claim 4 further comprising:

subtracting the last preemption time from a current time to determine a current time interval, wherein the current time interval is an interval of time since the last priority preemption of a process took place; and

determining whether the preemption interval has expired, wherein the preemption interval is expired if the current time interval is greater than or equal to the preemption interval.

6. The computer implemented method of claim 1 further comprising:

terminating execution of the currently running process; and

activating execution of a higher priority.

7. The computer implemented method of claim 1 wherein the preemption interval is a user defined amount of time.

8. The computer implemented method of claim 1 wherein the preemption interval is a default amount of time.

9. The computer implemented method of claim 1 further comprising:

receiving a new process that is a higher priority process than the currently running process;

adding the new process to a run queue associated with the processor; and

preempting the currently running process if the preemption interval has expired.

10. The computer implemented method of claim 1 further comprising:

determining whether the new process is a higher priority process than a currently running process based on a comparison of a predefined priority value for the new process and a predefined priority value for the currently running process.

11. An apparatus for controlling preemption rates, the apparatus comprising:

a computer comprising;

a storage device connected to a bus, wherein the storage device contains a computer usable program product; and

a processor, wherein the processor unit executes the computer usable program code to identify a preemption interval in response to a plurality of processes being executed by a processor, wherein only a single preemption of a process occurs during the preemption interval; and

preempt a currently running process only once during the preemption interval, wherein the preemption interval is adjusted to increase performance in executing processes.

12. A computer program product comprising:

a computer usable medium including computer usable program code for controlling preemption rates, said computer program product comprising;

computer usable program code for identifying a preemption interval, wherein only a single preemption of a process occurs during the preemption interval, in response to a plurality of processes being executed by a processor; and

computer usable program code for preempting a currently running process only once during the preemption interval, wherein the preemption interval is adjusted to increase performance in executing processes.

13. The computer program product of claim 12 further comprising:

computer usable program code for setting a preemption timer, wherein the preemption timer expires at the end of the preemption interval; and

computer usable program code for performing a preemption of the currently running process in response to a determination that the preemption timer has expired.

14. The computer program product of claim 12 further comprising:

computer usable program code for adjusting the preemption interval to form an updated preemption interval.

15. The computer program product of claim 12 further comprising:

computer usable program code for setting a last preemption time as a current time in response to performing a priority preemption, wherein the last preemption time is a time at which the most recently performed priority preemption of a process took place.

16. The computer program product of claim 15 further comprising:

computer usable program code for subtracting the last preemption time from a current time to determine a current time interval, wherein the current time interval is an interval of time since the last priority preemption took place; and

computer usable program code for determining whether the current time interval has expired, wherein the preemption interval is expired if the current time interval is greater than or equal to the preemption interval.

17. The computer program product of claim 12 further comprising:

computer usable program code for terminating execution of the currently running process; and

computer usable program code for activating execution of a higher priority process.

18. The computer program product of claim 12 wherein the preemption interval is a user defined amount of time.

19. The computer program product of claim 12 further comprising:

computer usable program code for receiving a new process that is a higher priority process than the currently running process;

adding a new process to a run queue associated with the processor; and

preempting the currently running process if the preemption interval has expired.

20. A system for controlling preemption rates, the system comprising:

a processor, wherein the processor is executing a process in a plurality of processes waiting to be executed to form a currently running process; and

a scheduler, wherein the scheduler identifies a preemption interval and preempts the currently running process, wherein only a single preemption of a process occurs during the preemption interval, and wherein the currently running process is only preempted once during the preemption interval, and wherein the preemption interval is adjusted to increase performance in executing processes.