SYMMETRIC MULTI-PROCESSOR LOCK TRACING

• US 20110113406A1
• Filed: 11/10/2009
• Published: 05/12/2011
• Est. Priority Date: 11/10/2009
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Fried, Eric P., Mewhinney, Greg R., Whitworth, David B., Flemming, Diane G.
• Granted Patent: US 8,453,122 B2
• Time in Patent Office: Days
• US Class Current: 717/128
• CPC Class Codes: G06F 11/3404 for parallel or distributed programming
• CPC Class Codes: G06F 11/3409 for performance assessment
• CPC Class Codes: G06F 11/3471 Address tracing
• CPC Class Codes: G06F 11/3636 by tracing the execution of the program
• CPC Class Codes: G06F 2201/865 Monitoring of software
• CPC Class Codes: G06F 2201/885 Monitoring specific for caches

Abstract

A symmetric multi-processor SMP system includes an SMP processor and operating system OS software that performs automatic SMP lock tracing analysis on an executing application program. System administrators, users or other entities initiate an automatic SMP lock tracing analysis. A particular thread of the executing application program requests and obtains a lock for a memory address pointer. A subsequent thread requests the same memory address pointer lock prior to the particular thread release of that lock. The subsequent thread begins to spin waiting for the release of that address pointer lock. When the subsequent thread reaches a predetermined maximum amount of wait time, MAXSPIN, a lock testing tool in the kernel of the OS detects the MAXSPIN condition. The OS performs a test to determine if the subsequent thread and address pointer lock meet the list of criteria set during initiation of the automatic lock trace method. The OS initiates an SMP lock trace capture automatically if all criteria or the arguments of the lock trace method are met. System administrators, software programmers, users or other entities interpret the results of the SMP lock tracing method that the OS stores in a trace table to determine performance improvements for the executing application program.

Claims

1. A method of testing, comprising:

determining, by a lock testing tool, when a particular thread of an executing program in a multi-processor system reaches a predetermined spin threshold; and

commencing, by the lock testing tool, a lock trace operation in response to the particular thread reaching the predetermined spin threshold.

2. The method of claim 1, wherein the particular thread waits to access a memory location because another thread exerts a first lock on the memory location.

3. The method of testing of claim 1, wherein the lock testing tool is included in an operating system of the symmetrical multiprocessing system.

4. The method of testing of claim 2, wherein the lock testing tool stores a list of locks designated for testing, the first lock being included in the list of locks.

5. The method of claim 4, further comprising:

testing, by the lock testing tool, to determine if the first lock is included in the list of locks,

such that the lock testing tool commences the lock trace operation when the particular thread reaches the predetermined spin threshold and the particular thread requests ownership of the first lock, provided the first lock is included in the list of locks.

6. The method of claim 1, wherein the lock testing tool initiates the lock trace operation provided that the particular thread has not exceeded a predetermined number of traces per time period.

7. The method of claim 1, wherein the lock testing tool receives as input a maximum number of traces to capture per time period in the lock trace operation.

8. An information handling system (IHS), comprising

a multi-processor system,

a memory coupled to the multi-processor system, the memory being configured with a lock tracing tool that:

determines when a particular thread of an executing program in the multi-processor system reaches a predetermined spin threshold; and

commences a lock trace operation in response to the particular thread reaching the predetermined spin threshold.

9. The IHS of claim 8, wherein the particular thread waits to access a memory location because another thread exerts a first lock on the memory location.

10. The IHS of claim 8, wherein the memory is further configured with an operating system that includes the lock tracing tool.

11. The IHS of claim 9, wherein the lock testing tool includes a list of locks designated for testing, the first lock being included in the list of locks.

12. The IHS of claim 11, wherein the lock testing tool tests to determine if the first lock is included in the list of locks, such that the lock testing tool commences the lock trace operation when the particular thread reaches the predetermined spin threshold and the particular thread requests ownership of the first lock, provided the first lock is included in the list of locks.

13. The IHS of claim 8, wherein the lock testing tool initiates the lock trace operation provided that the particular thread has not exceeded a predetermined number of traces per time period.

14. The IHS of claim 8, wherein the lock testing tool receives as input a maximum number of traces to capture per time period in the lock trace operation.

15. A computer program product stored on a computer operable medium, comprising:

instructions that determine when a particular thread of an executing program in a multi-processor system reaches a predetermined spin threshold; and

instructions that commence a lock trace operation in response to the particular thread reaching the predetermined spin threshold.

16. The computer program product of claim 15, wherein the particular thread waits to access a memory location because another thread exerts a first lock on the memory location.

17. The computer program product of claim 16, further comprising instructions that store a list of locks designated for testing, the first lock being included in the list of locks.

18. The computer program product of claim 17, further comprising instructions that test to determine if the first lock is included in the list of locks, such that the lock trace operation commences when the particular thread reaches the predetermined spin threshold and the particular thread requests ownership of the first lock, provided the first lock is included in the list of locks.

19. The computer program product of claim 15, further comprising instructions that initiate the lock trace operation provided that the particular thread has not exceeded a predetermined number of traces per time period.

20. The computer program product of claim 15, further comprising instructions that receive as input a maximum number of traces to capture per time period in the lock trace operation.