DYNAMIC PRIORITY QUEUING

• US 20110246996A1
• Filed: 04/05/2010
• Published: 10/06/2011
• Est. Priority Date: 04/05/2010
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Tunning, Brian R.
• Granted Patent: US 8,468,534 B2
• Time in Patent Office: Days
• US Class Current: 718/103
• CPC Class Codes: G06F 2209/486 Scheduler internals
• CPC Class Codes: G06F 2209/5013 Request control
• CPC Class Codes: G06F 2209/5021 Priority
• CPC Class Codes: G06F 2209/548 Queue
• CPC Class Codes: G06F 9/4881 Scheduling strategies for dispatcher, e.g. round robin, multi-level priority queues

Abstract

Techniques are provided for dynamically re-ordering operation requests that have previously been submitted to a queue management unit. After the queue management unit has placed multiple requests in a queue to be executed in an order that is based on priorities that were assigned to the operations, the entity that requested the operations (the “requester”) sends one or more priority-change messages. The one or more priority-change messages include requests to perform operations that have already been queued. For at least one of the operations, the priority assigned to the operation in the subsequent request is different from the priority that was assigned to the same operation when that operation was initially queued for execution. Based on the change in priority, the operation whose priority has change is placed at a different location in the queue, relative to the other operations in the queue that were requested by the same requester.

Claims

1. A method for scheduling operations, comprising:

maintaining a queue of to-be-executed operations, wherein the to-be-executed operations are executed in an order based on relative positions of the to-be-executed operations within the queue;

receiving, from an operation requester, one or more first requests for execution of a plurality of operations;

wherein each operation of the plurality of operations has an initial priority designation specified by the operation requester in the one or more first requests;

in response to the one or more first requests, placing the plurality of operations in a corresponding first plurality of positions within the queue;

wherein the first plurality of positions are selected based at least in part on the initial priority designations of the corresponding operations;

after the plurality of operations have been placed in the queue and before the plurality of operations have been executed, receiving, from the operation requester, one or more priority-change messages for the plurality of operations;

wherein each operation of the plurality of operations has a second priority designation specified by the operation requester in the one or more priority-change messages;

wherein, for at least one operation of the plurality of operations, the second priority designation is different than the initial priority designation;

in response to the one or more priority-change messages that indicate a different priority for the at least one operation, changing the position, within the queue, of said least one operation;

wherein the method is performed by one or more computing devices.

2. The method of claim 1 further comprising:

after the plurality of operations have been placed in the queue and before receiving the one or more priority-change messages, providing to the operation requester information about operations, within the queue, that have been requested by the operation requester.

3. The method of claim 2 wherein providing the information to the operation requester is performed in response to a request from the operation requester.

4. The method of claim 2 wherein providing the information to the operation requester is performed in response to the end of an interval of time.

5. The method of claim 2 wherein:

the one or more first requests include metadata associated with the plurality of operations; and

the step of providing the information to the operation requester includes providing the metadata to the operation requester.

6. The method of claim 5 wherein the metadata associated with each operation request includes information used by the operation requestor to determine the second priority designation for the operation request.

7. The method of claim 2 wherein the step of providing the information includes providing to the operation requester the initial priority designation for each of the plurality of operations.

8. The method of claim 1 wherein:

the queue includes operations requested by one or more other requestors, and

the step of changing the position of said at least one operation is performed without changing the position, within the queue, of any operation requested by any of said one or more other requestors.

9. The method of claim 1 wherein:

the queue includes operations requested by one or more other requestors, and

more operations of said requestor are ahead of a particular queued operation of another requestor than were ahead of the particular queued operation prior to changing the position of said at least one operation.

10. The method of claim 1 wherein the queue is maintained by an operating system of a device, and queues operations requested by applications running on the device.

11. The method of claim 1 wherein the queue is maintained by routines in a shared library, and queues operations requested by a plurality of applications that are sharing said shared library.

22. The method of claim 11 further comprising:

the operation requestor including tags with the first one or more requests;

after sending the one or more first requests, and before sending the one or more priority-change messages, the operation requestor performing the steps of;

detecting a priority-changing event;

in response to detecting the priority-changing event, sending a queue information request to the queue management unit;

receiving, as a response to the queue information request, information about operations currently queued by the queue management unit for the operation requester;

wherein the information includes tags associated with the operations that are currently queued; and

determining the second priority designations based, at least in part, on the tags.

12. A computer-readable storage storing instructions for scheduling operations, said instructions including instructions which, when executed by one or more processors, cause:

maintaining a queue of to-be-executed operations, wherein the to-be-executed operations are executed in an order based on relative positions of the to-be-executed operations within the queue;

receiving, from an operation requester, one or more first requests for execution of a plurality of operations;

wherein each operation of the plurality of operations has an initial priority designation specified by the operation requester in the one or more first requests;

in response to the one or more first requests, placing the plurality of operations in a corresponding first plurality of positions within the queue;

wherein the first plurality of positions are selected based at least in part on the initial priority designations of the corresponding operations;

after the plurality of operations have been placed in the queue and before the plurality of operations have been executed, receiving, from the operation requester, one or more priority-change messages for the plurality of operations;

wherein each operation of the plurality of operations has a second priority designation specified by the operation requester in the one or more priority-change messages;

wherein, for at least one operation of the plurality of operations, the second priority designation is different than the initial priority designation;

in response to the one or more priority-change messages that indicate a different priority for the at least one operation, changing the position, within the queue, of said least one operation;

wherein the method is performed by one or more computing devices.

13. The computer-readable storage of claim 12 further comprising instructions for:

after the plurality of operations have been placed in the queue and before receiving the one or more priority-change messages, providing to the operation requester information about operations, within the queue, that have been requested by the operation requester.

14. The computer-readable storage of claim 13 wherein providing the information to the operation requester is performed in response to a request from the operation requester.

15. The computer-readable storage of claim 13 wherein providing the information to the operation requester is performed in response to the end of an interval of time.

16. The computer-readable storage of claim 13 wherein:

the one or more first requests include metadata associated with the plurality of operations; and

the step of providing the information to the operation requester includes providing the metadata to the operation requester.

17. The computer-readable storage of claim 16 wherein the metadata associated with each operation request includes information used by the operation requestor to determine the second priority designation for the operation request.

18. The computer-readable storage of claim 13 wherein the step of providing the information includes providing to the operation requester the initial priority designation for each of the plurality of operations.

19. The computer-readable storage of claim 12 wherein:

the queue includes operations requested by one or more other requestors, and

the step of changing the position of said at least one operation is performed without changing the position, within the queue, of any operation requested by any of said one or more other requestors.

20. The computer-readable storage of claim 12 wherein:

the queue includes operations requested by one or more other requestors, and

more operations of said requestor are ahead of a particular queued operation of another requestor than were ahead of the particular queued operation prior to changing the position of said at least one operation.

21. A method for scheduling operations, comprising:

sending, from on operation requestor to a queue management unit, one or more first requests for execution of a plurality of operations to cause the queue management unit to place the plurality of operations in a corresponding first plurality of positions within a queue;

wherein to-be-executed operations in the queue are executed in an order based on relative positions of the to-be-executed operations within the queue;

wherein each operation of the plurality of operations has an initial priority designation specified by the operation requester in the one or more first requests;

wherein the first plurality of positions are selected by the queue management unit based at least in part on the initial priority designations of the corresponding operations;

after sending the one or more first requests, the operation requestor sending to the queue management unit one or more priority-change messages for execution of the plurality of operations;

wherein each operation of the plurality of operations has a second priority designation specified by the operation requester in the one or more priority-change messages;

wherein, for at least one operation of the plurality of operations, the second priority designation is different than the initial priority designation;

wherein the one or more priority-change messages cause the queue management unit to change the position, within the queue, of said least one operation;

wherein the method is performed by one or more computing devices.