Computer system, program product and method for dynamically optimizing a communication protocol for supporting more users

• US 6,052,737 A
• Filed: 04/15/1998
• Issued: 04/18/2000
• Est. Priority Date: 04/15/1998
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Bitton, Yosef, Nelson, Randall Scott
• Primary Examiner(s): Maung, Zarni
• Assistant Examiner(s): Barot, Bharat
• Application Number:
  US09/060,993
• Time in Patent Office: 734 Days
• Field of Search: 709/223, 709/227-228, 709/230, 709/236, 709/238, 709/242, 709/246, 709/248, 709/259, 714/48, 714/55, 714/700, 714/703, 714/707, 714/708
• US Class Current: 709/248
• CPC Class Codes: H04L 69/28 Timers or timing mechanisms used in protocols
• CPC Class Codes: H04L 9/40 Network security protocols

Abstract

A computer system, program product and method enhances the operation of a communications protocol by monitoring timers associated with the protocol to determine the transmission requirements placed on a transmit queue. The number of frames to be enqueued at a particular system tick is dynamically modified to prevent queue overload. In one embodiment the expiration of timers is adjusted to prevent queue overload. In another embodiment, frame transmission at timer expiry is adjusted to prevent queue overload.

Claims

1. A method for processing frames between links of a network using protocol timers which expire on operating system ticks, the method comprising:

when starting a protocol timer, determining an operating system tick corresponding to the expiration of the protocol timer;

determining an actual number of other protocol timers expiring on the same operating system tick and comparing the actual number to a timer limit number; and

if the actual number exceeds the timer limit number, setting the current protocol timer to expire on a different operating system tick subsequent to the operating system tick on which it is originally set to expire.

2. The method of claim 1 further comprising:

determining the actual number of protocol timers expiring on the subsequent operating system tick; and

if the actual number for expiring on the subsequent operating system tick exceeds the timer limit number, setting the current protocol timer to expire on still another subsequent operating system tick.

3. The method of claim 2 further comprising:

continuing to determine the actual number of protocol timers expiring on the another subsequent operating ticks; and

setting the current protocol timer to expire on the first available operating system tick wherein the actual number of protocol timers expiring thereon is less than said timer limit number.

4. The method of claim 1 further comprising using a timer table with an index which is incremented through entries of the table to determine the actual number of other protocol timers expiring on an operating system tick.

5. The method of claim 4 wherein said index corresponds to an operating system tick.

6. The method of claim 4 wherein each table entry points to at least one timer list containing another timer set to expire on said same operating system tick.

7. The method of claim 1 further comprising maintaining a count for establishing said actual number of other protocol timers expiring on said same operating system tick.

8. The method of claim 1 wherein said protocol timers are IEEE 802.2 protocol timers, including T1, Ti, and T2 timers, the method further comprising:

before setting the current protocol timer to expire on a different operating system tick, determining if timer is a T2 timer; and

if the timer is a T2 timer, letting it expire on original operating system tick.

9. The method of claim 7 further comprising:

decrementing said count when a timer expires for dynamically modifying the number of timers expiring on a particular operating system tick.

10. The method of claim 7 further comprising:

decrementing said count when a timer is cancelled for dynamically modifying the number of timers expiring on a particular operating system tick.

11. A method for processing frames between links of a network using protocol timers which expire on operating system ticks, the method comprising:

monitoring the expiration of a protocol timer and determining the corresponding operating system tick for the expiration;

upon expiration of the protocol timer, checking the depth of a transmit queue;

if the queue is not in a full state, processing frames associated with the protocol timer expiration on the corresponding operating system tick; and

if the queue is in a full state, processing frames associated with the protocol timer expiration on a subsequent operating system tick.

12. The method of claim 11 further comprising processing frames associated with the protocol timer on the subsequent operating system tick ahead of other frames to be processed on that same subsequent operating system tick.

13. The method of claim 11 wherein said protocol timers are IEEE 802.2 protocol timers including T1, Ti, and T2 timers, the method further comprising:

determining if an expiring protocol timer is a T2 timer; and

if it is a T2 timer, processing frames associated with the protocol timer expiration on the corresponding operating system tick regardless of the depth of the transmit queue.

14. The method of claim 13 further comprising:

determining all the protocol timers expiring on the corresponding operating system tick;

processing frames associated with one of the T1 and Ti timers; and

subsequently processing frames associated with T2 timers.

15. A computer system comprising:

a data communications system operable for interfacing with a network and responsive to a protocol timer for processing frames over the network upon the expiration of the protocol timer on an operating system tick; and

a processor, coupled to the communications system, the processor configured for monitoring the protocol timer to determine the operating system tick on which the protocol timer expires, the processor further configured to determine the actual number of other protocol timers expiring on the same operating system tick and, when said actual number of timers exceeds a timer limit number, setting the current protocol timer to expire on a different operating system tick subsequent to the original operating system tick on which it is originally set to expire.

16. The computer system of claim 15 wherein said processor is further configured to determine the number of protocol timers expiring on the subsequent operating system tick and, if the number of protocol timers expiring on the subsequent operating system tick exceeds the timer limit number, to set the protocol timer to expire on another subsequent operating system tick.

17. The computer system of claim 16 wherein the processor is further configured to continue to determine the number of protocol timers expiring on said another subsequent operating system ticks, and to set the protocol timer to expire on the first available operating system tick wherein the number of protocol timers expiring thereon is less than said timer limit number.

18. The computer system of claim 15 further comprising a timer table including an index which is incremented through entries of the table corresponding to protocol timers expiring on an operating system tick, the processor further configured to interface with the table to determine the actual number of protocol timers expiring on the same operating system tick.

19. The computer system of claim 15 wherein said processor is configured to maintain a count corresponding to said actual number of protocol timers expiring on the same operating system tick.

20. The computer system of claim 15 wherein said communications system includes an IEEE 802.2 protocol with protocol timers including T1, Ti and T2 timers, the processor further configured to determine if a timer is a T2 timer, and if it is, letting it expire on the original operating system tick.

21. A computer system comprising:

a data communications system operable for interfacing with a network and responsive to a protocol timer for processing frames on the network upon the expiration of the protocol timer on an operating system tick;

the data communications system including a transmit queue for receiving frames to be processed on the network upon the expiration of the protocol timer;

a processor, coupled to the communications system, the processor configured for monitoring the expiration of the protocol timer and for determining the operating system tick on which the protocol timer expires; and

the processor further configured for checking, upon protocol timer expiration, the depth of the transmit queue, and if the queue is not in a full state, processing the frames associated with the protocol timer on the corresponding operating system tick, but if the queue is in a full state, processing the frames associated with the protocol timer on a subsequent operating system tick.

22. The computer system of claim 21 wherein said processor is configured for processing frames associated with the protocol timer on the subsequent operating system tick ahead of frames to be processed on that same subsequent operating system tick.

23. The computer system of claim 21 wherein said communications system includes an IEEE 802.2 protocol with protocol timers including T1, Ti, and T2 timers, the processor further configured to determine if a timer is a T2 timer, and if it is, processing frames associated with the protocol timer expiration on the corresponding operating system tick regardless of the depth of the transmit queue.

24. A program product, comprising:

(a) a program for interfacing with a communications system which establishes links between networked devices by utilizing protocol timers which expire on operating system ticks, the program configured to perform a method of managing the protocol timer expiries for supporting more links in the communications system, the method comprising;

(1) when starting a protocol timer, determining an operating system tick corresponding to the expiration of the protocol timer;

(2) determining an actual number of other protocol timers expiring on the same operating system tick and comparing the actual number to a timer limit number;

(3) if the actual number exceeds the timer limit number, setting the current protocol timer to expire on a different operating system tick subsequent to the operating system tick on which it is originally set to expire; and

(b) a signal bearing media bearing the program.

25. A program product, comprising:

(a) a program for interfacing with a communications system which establishes links between networked devices by utilizing protocol timers which expire on operating system ticks, the program configured to perform a method of managing the protocol timer expiries for supporting more links in the communications system, the method comprising;

(1) monitoring the expiration of a protocol timer and determining the corresponding operating system tick for the expiration;

(2) upon expiration of the protocol timer, checking the depth of a transmit queue;

(3) if the queue is not in a full state, processing frames associated with the protocol timer expiration on the corresponding operating system tick; and

(4) if the queue is in a full state, processing the frames associated with the protocol timer expiration on a subsequent operating system tick; and

(b) a signal bearing media bearing the program.