Shared resource access via declarations that contain a sequence number of a packet

• US 6,978,330 B1
• Filed: 04/04/2002
• Issued: 12/20/2005
• Est. Priority Date: 04/04/2002
• Status: Active Grant

• Current Assignee: OL Security LLC (Intellectual Ventures LLC)
• Original Assignee: Applied Micro Circuits Corporation (MACOM Technology Solutions Holdings, Inc.)
• Inventors: Joffe, Alexander, Khamisy, Asad
• Primary Examiner(s): Myers, Paul R.
• Assistant Examiner(s): PHAN, RAYMOND NGAN
• Application Number:
  US10/117,780
• Time in Patent Office: 1,356 Days
• Field of Search: 710/200, 710/240, 710241-244, 710/108, 710/113, 710/118, 710/125, 710308-311, 709100-108
• US Class Current: 710/240
• CPC Class Codes: G06F 9/526 Mutual exclusion algorithms

Abstract

Logic (also called “re-ordering semaphore”) issues semaphore grants to access a shared resource in an order different from the order in which semaphore requests for accessing the shared resource are received. The re-ordering semaphore needs to receive a semaphore release between any two semaphore grants. There is no limit on the duration between a semaphore grant and a semaphore release, so that a task that receives a semaphore grant can use the shared resource for any length of time. In one embodiment, each request is associated with a number indicative of the order in which grants are to be issued, and the re-ordering semaphore uses this number in deciding which request is to be granted. The number can be a sequence number that is indicative of the order of arrival of packets that generated the requests.

Claims

1. A method of obtaining access to a shared resource, the method comprising:

issuing a first declaration indicative of a possible need in future to access the shared resource, and providing a sequence number in said first declaration;

executing software until access to the shared resource is needed or not needed;

issuing a request to access the shared resource and providing said sequence number in said request, if access is needed; and

issuing a second declaration indicative of no need in future to access the shared resource and providing said sequence number in said second declaration;

wherein the sequence number indicates an order of arrival of packets whose information is being processed by said executing software.

2. The method of claim 1 further comprising:

enabling sequencing when requesting access; and

disabling updating of a current pointer indicative of said sequence number.

3. The method of claim 1 further comprising:

issuing a release to indicate an end to use of the shared resource and providing said sequence number in said release.

4. The method of claim 1 further comprising:

receiving a grant, subsequent to issuing the request;

wherein the grant is received in said order of arrival of packets;

using the shared resource for any length of time, after receiving the grant; and

issuing a release to indicate an end to use of the shared resource and providing said sequence number in said release, after using the shared resource.

5. The method of claim 1 wherein the sequence number is one of a plurality of sequence numbers, and each sequence number in said plurality is mapped to one of a plurality of locations in an array, and the method further comprises:

updating a value, at a location in the array for said sequence number, in response to each issuing.

6. The method of claim 2 further comprising:

issuing a release to indicate an end to use of the shared resource providing said sequence number in said release, and enabling updating of said current pointer.

7. The method of claim 4 further comprising:

maintaining a pointer unchanged, between said grant and said release;

wherein said pointer indicates a task that performs said using of the shared resource.

8. The method of claim 4 further comprising:

suspending a task that performs said issuing of said request to access the shared resource until receipt of said grant;

wherein said task performs said using of the shared resource only after receipt of said grant.

9. The method of claim 6 further comprising:

using the shared resource for any length of time between disabling updating and enabling updating.

10. A circuit for accessing a shared resource, the circuit comprising:

means for issuing a first declaration indicative of a possible need in future to access the shared resource, and for providing a sequence number in said first declaration;

means for executing software until access to the shared resource is needed or not needed;

means for issuing a request to access the shared resource and providing said sequence number in said request, if access is needed; and

means for issuing a second declaration indicative of no need in future to access the shared resource, and for providing said sequence number in said second declaration;

wherein the sequence number indicates an order of arrival of packets whose information is being processed by said executing software.

11. The circuit of claim 10 further comprising:

means for enabling sequencing when requesting access; and

means for disabling updating of a current pointer indicative of said sequence number.

12. The circuit of claim 10 further comprising:

means for issuing a release to indicate an end to use of the shared resource and providing said sequence number in said release.

13. The circuit of claim 10 further comprising:

means for receiving a grant;

means for using the shared resource for any length of time, subsequent to receipt of the grant; and

means for issuing a release to indicate an end to use of the shared resource and providing said sequence number in said release.

14. The circuit of claim 10 wherein the sequence number is one of a plurality of sequence numbers, and each sequence number in said plurality is mapped to one of a plurality of locations in an array, and the circuit further comprises:

means for updating a value, at a location in the array for said sequence number, in response to each issuing.

15. The circuit of claim 11 further comprising:

means for issuing a release to indicate an end to use of the shared resource, providing said sequence number in said release, and enabling updating of said current pointer.

16. The circuit of claim 13 further comprising:

means for maintaining a pointer unchanged, between said grant and said release;

wherein said pointer indicates a task that performs said using of the shared resource.

17. The circuit of claim 13 further comprising:

means for suspending a task that performs said issuing of said request to access the shared resource until receipt of said grant;

wherein said task performs said using of the shared resource only after receipt of said grant.

18. The circuit of claim 15 further comprising:

means for using the shared resource for any length of time between disabling updating and enabling updating.

19. A method of obtaining access to a shared resource, the method comprising:

issuing a first declaration indicative of a possible need in future to access the shared resource, and providing a number in said first declaration;

executing software until access to the shared resource is needed or not needed;

issuing a request to access the shared resource and providing said number in said request if access is needed; and

issuing a second declaration indicative of no need in future to access the shared resource, and providing said number in said second declaration;

wherein said number indicates an order in which grants are to be issued.

20. The method of claim 19 wherein:

the order is of arrival of packets.

21. The method of claim 19 further comprising:

issuing a release to indicate an end to use of the shared resource and providing said number in said release.

22. The method of claim 19 further comprising:

receiving a grant, subsequent to issuing the request;

wherein the grant is received in said order;

using the shared resource for any length of time, after receiving the grant; and

issuing a release to indicate an end to use of the shared resource and providing said number in said release, after using the shared resource.