System and method for adding priority change value corresponding with a lock to a thread during lock processing

• US 7,278,141 B2
• Filed: 04/23/2003
• Issued: 10/02/2007
• Est. Priority Date: 04/23/2003
• Status: Expired due to Fees

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: International Business Machines Corporation
• Inventors: Dunshea, Andrew, Michel, Dirk, Accapadi, Jos Manuel, Van Fleet, James W.
• Primary Examiner(s): An; Meng-Al T.
• Assistant Examiner(s): WAI, ERIC CHARLES
• Application Number:
  US10/422,037
• Publication Number:
  US 20040216112A1
• Time in Patent Office: 1,623 Days
• Field of Search: 718/1, 718102-104, 713/400
• US Class Current: 718/103
• CPC Class Codes: G06F 9/4881 Scheduling strategies for dispatcher, e.g. round robin, multi-level priority queues
• CPC Class Codes: G06F 9/526 Mutual exclusion algorithms

Abstract

A system and method is altering the priority of a process, or thread of execution, when the process acquires a software lock. The priority is altered when the lock is acquired and restored when the process releases the lock. Thread priorities can be altered for every lock being managed by the operating system or can selectively be altered. In addition, the amount of alteration can be individually adjusted so that a process that acquires one lock receive a different priority boost than a process that acquires a different lock. Furthermore, a method of tuning a computer system by adjusting lock priority values is provided.

Claims

1. A method for altering a priority of a thread of execution that is being executed by a computer operating system, said method comprising:

receiving a request for a software lock from the thread, wherein the software lock is a data structure used to control access to a shared resource;

determining that the software lock is available;

granting the thread access to the shared resource in response to the determination;

retrieving a priority change value corresponding to the software lock;

altering the priority of the thread in conjunction with the granting by adding the priority change value to the priority of the thread;

receiving a release instruction from the thread;

revoking the access previously granted in response to receiving the release instruction; and

readjusting the priority of the thread in conjunction with the revoking by subtracting the priority change value from the priority of the thread.

2. The method of claim 1 further comprises:

after the altering, applying an algorithm to the priority of the thread, the application resulting in a new priority;

determining a penalty value between the priority and the new priority;

storing the penalty value; and

readjusting the priority of the thread by subtracting the penalty value and the priority change value in response to the thread releasing the software lock.

3. The method of claim 1 further comprising:

initializing a plurality of priority change values prior to receiving the request, each of the priority change values corresponding to a different software lock; and

retrieving the priority change value corresponding to the requested software lock prior to the altering, wherein the altering includes adjusting the priority change value by the retrieved priority change value by adding the priority change value to the priority of the thread.

4. The method of claim 3 further comprising:

testing the computer operating system following the initialization of the plurality of priority change values; and

changing one or more of the plurality of priority change values in response to the testing.

5. The method of claim 1 wherein the software lock is determined to be available regardless of the priority of the thread, and wherein the thread is granted access to the shared resource even when the priority of the thread is greater than the priority change value that corresponds to the software lock.

6. The method of claim 1 wherein the priority change value corresponding to the software lock is retrieved from a plurality of priority change values that correspond to the software lock, the method further comprising:

selecting the retrieved priority change value from the plurality of priority change values based upon an identifier that corresponds to the thread.

7. An information handling system comprising:

one or more processors;

a memory accessible by the processors;

a nonvolatile storage device accessible by the processors;

a computer operating system for controlling the use of the processors, the memory, and the storage device, the computer operating system including one or more software lock data structures used to control access to shared resources;

a software lock tool for altering a priority of a thread of execution that is being executed by the computer operating system, the software lock tool performing steps that include;

altering a priority of a thread of execution that is being executed by a computer operating system, said method comprising;

receiving a request for a software lock from the thread, wherein the software lock is a data structure used to control access to a shared resource;

determining that the software lock is available;

granting the thread access to the shared resource in response to the determination;

retrieving a priority change value corresponding to the software lock;

altering the priority of the thread in conjunction with the granting by adding the priority change value to the priority of the thread;

receiving a release instruction from the thread;

revoking the access previously granted in response to receiving the release instruction; and

readjusting the priority of the thread in conjunction with the revoking by subtracting the priority change value from the priority of the thread.

8. The information handling system of claim 7 with additional steps comprising:

after the altering, applying an algorithm to the priority of the thread, the application resulting in a new priority;

determining a penalty value between the priority and the new priority;

storing the penalty value; and

readjusting the priority of the thread by subtracting the penalty value and the priority change value in response to the thread releasing the software lock.

9. The information handling system of claim 7 wherein the software lock tool performs further steps comprising:

initializing a plurality of priority change values prior to receiving the request, each of the priority change values corresponding to a different software lock; and

retrieving the priority change value corresponding to the requested software look prior to the altering, wherein the altering includes adjusting the priority change value by the retrieved priority change value by adding the priority change value to the priority of the thread.

10. The information handling system of claim 7 wherein the software lock is determined to be available regardless of the priority of the thread, and wherein the thread is granted access to the shared resource even when the priority of the thread is greater than the priority change value that corresponds to the software lock.

11. The information handling system of claim 7 wherein the priority change value corresponding to the software lock is retrieved from a plurality of priority change values that correspond to the software lock, wherein the software lock tool performs further steps comprising:

selecting the retrieved priority change value from the plurality of priority change values based upon an identifier that corresponds to the thread.

12. A computer program product stored in a computer storage media for altering a priority of a thread of execution that is being executed by a computer operating system, said computer program product including instructions that, when executed by an information handling system, causes the information handling system to perform actions comprising:

receiving a request for a software lock from the thread, wherein the software lock is a data structure used to control access to a shared resource;

determining that the software lock is available;

granting the thread access to the shared resource in response to the determination;

retrieving a priority change value corresponding to the software lock;

altering the priority of the thread in conjunction with the granting by adding the priority change value to the priority of the thread;

receiving a release instruction from the thread;

revoking the access previously granted in response to receiving the release instruction; and

readjusting the priority of the thread in conjunction with the revoking by subtracting the priority change value from the priority of the thread.

13. The computer program product of claim 12 wherein the actions further comprise:

after the altering, applying an algorithm to the priority of the thread, the application resulting in a new priority;

determining a penalty value between the priority and the new priority;

storing the penalty value; and

readjusting the priority of the thread by subtracting the penalty value and the priority change value in response to the thread releasing the software lock.

14. The computer program product of claim 12 wherein the actions further comprise:

initializing a plurality of priority change values prior to receiving the request, each of the priority change values corresponding to a different software lock; and

retrieving the priority change value corresponding to the requested software lock prior to the altering, wherein the altering includes adjusting the priority change value by the retrieved priority change value by adding the priority change value to the priority of the thread.

15. The computer program product of claim 14 further comprising:

testing the computer operating system following the initialization of the plurality of priority change values; and

changing one or more of the plurality of priority change values in response to the testing.

16. The computer program product of claim 12 wherein the software lock is determined to be available regardless of the priority of the thread, and wherein the thread is granted access to the shared resource even when the priority of the thread is greater than the priority change value that corresponds to the software lock.

17. The computer program product of claim 12 wherein the priority change value corresponding to the software lock is retrieved from a plurality of priority change values that correspond to the software lock, wherein the actions further comprise:

selecting the retrieved priority change value from the plurality of priority change values based upon an identifier that corresponds to the thread.