Identifying Code that Wastes Time Switching Tasks

• US 20070083274A1
• Filed: 10/12/2005
• Published: 04/12/2007
• Est. Priority Date: 10/12/2005
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Krauss, Kirk
• Granted Patent: US 8,095,921 B2
• Time in Patent Office: Days
• US Class Current: 700/4
• CPC Class Codes: G06F 11/3409 for performance assessment
• CPC Class Codes: G06F 11/3466 Performance evaluation by tracing or monitoring
• CPC Class Codes: G06F 11/3476 Data logging G06F11/14, G06F11/2205 take precedence
• CPC Class Codes: G06F 2201/865 Monitoring of software
• CPC Class Codes: G06F 2201/88 Monitoring involving counting

Abstract

A method of detecting portions of code of a computer program that protect resources of a computer system unnecessarily can include identifying threads and synchronization objects that are used by a computer program during execution, determining the number of threads that have accessed each resource while it has been consistently protected by a particular synchronization object, and indicating whether the resource is suited for protection according to the number of threads that have accessed the resource.

Claims

1. A method of detecting portions of code of a computer program that protect resources of a computer system unnecessarily, said method comprising:

identifying a synchronization object that has been engaged by a thread of the computer program;

while the synchronization object is engaged, recording each access of a resource of the computer system that is protected by the synchronization object and a thread associated with the access;

when the synchronization object is disengaged, determining a number of threads that have accessed the resource while protected by the synchronization object during execution of the computer program; and

indicating whether the resource protected by the synchronization object is suited for protection according to the number of threads that accessed the resource while the synchronization object was engaged during execution of the computer program.

2. The method of claim 1, said recording step further comprising:

for each resource that is accessed, determining whether state memory has been allocated for the resource; and

if not, allocating state memory for recording accesses to the resource.

3. The method of claim 2, said allocating step further comprising apportioning a number of state bits determined according to a number of synchronization objects that have been engaged in the computer program, a number of threads running in the computer program, and a measure of size of the resource.

4. The method of claim 3, said recording step further comprising, for each access of the resource, setting at least one bit corresponding to a thread responsible for the access and the synchronization object engaged during the access.

5. The method of claim 1, said indicating step further comprising, if more than one thread has accessed the resource during an execution of the program under test while the synchronization object was engaged, noting that the resource is suitable for protection by that synchronization object.

6. The method of claim 1, said indicating step further comprising, if a single thread accessed the resource while the synchronization object was engaged, noting that the resource is unsuitable for protection.

7. The method of claim 1, further comprising storing a call chain leading to a first access of the resource protected by the synchronization object.

8. The method of claim 7, said indicating step further comprising:

counting a number of instances in which the resource is deemed apparently unsuitable for protection; and

if the number of instances exceeds a predetermined threshold, indicating the call chain.

9. A method of detecting portions of code of a multithreaded computer program that cause unnecessary task switching within a computer system comprising:

identifying resources protected by synchronization objects during execution of the multithreaded computer program;

counting instances during execution of the multithreaded computer program in which a resource that is protected by a synchronization object is accessed by only a single thread that engaged the synchronization object; and

indicating that resources accessed by only the single thread that engaged the synchronization object during execution of the multithreaded program are unsuitable for protection by a synchronization object.

10. The method of claim 9, further comprising:

for each resource that is accessed while a synchronization object is engaged for the resource, determining whether state memory has been allocated; and

if not, allocating state memory for recording accesses to the resource.

11. The method of claim 10, said allocating step further comprising apportioning a number of state bits determined according to a number of synchronization objects that have been engaged in the multithreaded computer program, a number of threads running in the multithreaded computer program, and a measure of size of the resource.

12. The method of claim 11, said identifying step further comprising, for each access of a memory block, setting at least one bit corresponding to the thread responsible for the access and the synchronization object engaged during the access.

13. The method of claim 9, further comprising storing a call chain leading to a first access of the resource protected by the synchronization object.

14. The method of claim 13, said indicating step further comprising if the number of instances exceeds a predetermined threshold, indicating the call chain.

15. A machine readable storage, having stored thereon a computer program having a plurality of code sections comprising:

code for identifying resources protected by synchronization objects during execution of the multithreaded computer program;

code for counting instances during execution of the multithreaded computer program in which a resource that is protected by a synchronization object is accessed by only a single thread that engaged the synchronization object; and

code for indicating that resources accessed by only the single thread that engaged the synchronization object during execution of the multithreaded program are unsuitable for protection by a synchronization object.

16. The machine readable storage of claim 15, further comprising:

code for, for each resource that is accessed while a synchronization object is engaged for the resource, determining whether state memory has been allocated; and

code for, if not, allocating state memory for recording accesses to the resource.

17. The machine readable storage of claim 16, said code for allocating further comprising code for apportioning a number of state bits determined according to a number of synchronization objects that have been engaged in the multithreaded computer program, a number of threads running in the multithreaded computer program, and a measure of size of the resource.

19. The machine readable storage of claim 15, further comprising code for storing a call chain leading to a first access of the resource protected by the synchronization object.

20. The machine readable storage of claim 15, said code for indicating further comprising code for, if the number of instances exceeds a predetermined threshold, indicating the call chain.

18. The machine readable storage of claim 18, said code for identifying further comprising code for, for each access of a memory block, setting at least one bit corresponding to the thread responsible for the access and the synchronization object engaged during the access.