Adaptive Reader-Writer Lock

• US 20080209433A1
• Filed: 05/06/2008
• Published: 08/28/2008
• Est. Priority Date: 12/19/2000
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: McKenney, Paul E.
• Granted Patent: US 7,747,805 B2
• Time in Patent Office: Days
• US Class Current: 718/104
• CPC Class Codes: G06F 9/52 Program synchronisation; Mutual exclusion, e.g. by means of semaphores

Abstract

A method and computer system for dynamically selecting an optimal synchronization mechanism for a data structure in a multiprocessor environment. The method determines a quantity of read-side and write-side acquisitions, and evaluates the data to determine an optimal mode for efficiently operating the computer system while maintaining reduced overhead. The method incorporates data received from the individual units within a central processing system, the quantity of write-side acquisitions in the system, and data which has been subject to secondary measures, such as formatives of digital filters. The data subject to secondary measures includes, but is not limited to, a quantity of read-side acquisitions, a quantity of write-side acquisitions, and a quantity of read-hold durations. Based upon the individual unit data and the system-wide data, including the secondary measures, the operating system may select the most efficient synchronization mechanism from among the mechanisms available. Accordingly, efficiency of a computer system may be enhanced with the ability to selectively choose an optimal synchronization mechanism based upon selected and calculated parameters.

Claims

1. A computer system comprising:

multiple processors;

a counter for measuring read-side acquisitions by a unit within a computer processing system;

first and second system-wide measures of read and write acquisitions of said processors; and

a manager adapted to select a synchronization mechanism responsive to at least some of said measures.

2. The system of claim 1, wherein said synchronization mechanism is selected from the group consisting of:

a distributed reader-writer lock, a centralized reader-writer lock an exclusive lock, and RCU.

3. The system of claim 2, wherein said exclusive lock mode is selected from the group consisting of:

a test and set lock mode, a test and test and set lock mode, a queued lock mode, a ticket lock mode, and a quad-aware lock mode.

4. The system of claim 1, wherein the synchronization mechanism is a distributed reader-writer lock mode, and wherein said manager is responsive to the system-wide measure of write acquisitions and the system wide measure of read acquisitions.

5. The system of claim 1, wherein the synchronization mechanism is a centralized lock mode, and wherein said manager is responsive to the system-wide measure of write acquisitions and the system-wide measure of read acquisitions.

6. The system of claim 1, wherein the synchronization mechanism is a centralized lock mode, and wherein said manager is responsive to the system-wide measure of read acquisitions and a system-wide measure of read-hold duration.

7. The system of claim 1, wherein the synchronization mechanism is an exclusive lock mode and wherein said manager is responsive to a system-wide measure of read-hold duration.

8. In a multiprocessor system, an article comprising:

a tangible computer-readable medium;

means in the medium for maintaining a measure of read-side acquisitions by a unit within a computer processing system having multiple processors;

means in the medium for maintaining first and second system-wide measures of read and write acquisitions; and

means in the medium for selecting a synchronization mechanism responsive to at least some of said measures.

9. The article of claim 8, wherein the medium is a recordable data storage medium.

10. The article of claim 8, wherein said synchronization mechanism is selected from the group consisting of:

a distributed reader-writer lock, a centralized reader-writer lock, an exclusive lock, and RCU.

11. The article of claim 8, wherein the synchronization mechanism is a distributed reader-writer lock mode, and wherein said means in the medium for selecting a lock mode is responsive to the system-wide measure of write acquisitions and the system wide measure of read-acquisitions.

12. The article of claim 8, wherein the synchronization mechanism is a centralized lock mode, and wherein said means in the medium for selecting a synchronization mechanism is response to the system-wide measure of write acquisitions and the system-wide measure of read acquisitions.

13. The article of claim 8, wherein the synchronization mechanism is a centralized lock mode, and wherein said means in the medium for selecting a synchronization mechanism is responsive to a system-wide measure of read acquisitions and a system-wide measure of read-hold duration.

14. The article of claim 8, wherein the synchronization mechanism is an exclusive lock mode and wherein said means in the medium for selecting a synchronization mechanism is responsive to a system-wide measure of read-hold duration.

15. The article of claim 8, wherein at least some of said second system-wide measures are selected from a group consisting of:

a digital filter, a weighted average, a sliding window average, a finite impulse response, and a central data structure.