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Dual mode reader writer lock

A read-write lock, dual-mode technology, used in multi-programming devices, program synchronization, program control using stored programs, etc.

Inactive Publication Date: 2012-11-21
IBM CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

For example, one process should not be allowed to read data while another process is writing it

Method used

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Embodiment Construction

[0034] In some cases, several atomic operations of acquiring or releasing locks from several processes or threads for each request can be pending in the data processing system. The present invention recognizes that several atomic operations for RWL inundate the data processing system can adversely affect the performance of the data processing system.

[0035] For clarity of description, "process" refers to a thread or process of a process. Within the scope of the present invention, operations that are relative to processing are also applicable to threads, and operations that are relative to threads are also applicable to processing.

[0036] The present invention further recognizes that, in certain other situations, the lock data structure may become saturated and may not be able to accommodate any more lock requests. For example, if four threads have held read locks on the associated resource, it is assumed that a data word of size two bits will saturate since two bits can o...

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Abstract

A method, system, and computer usable program product for a dual mode reader writer lock. A contention condition is determined in using an original lock. The original lock manages read and write access to a resource by several processes executing in the data processing system. The embodiment creates a set of expanded locks for use in conjunction with the original lock. The original lock and the set of expanded locks forming the dual mode reader writer lock, which operates to manage the read and write access to the resource. Using an index within the original lock, each expanded lock is indexed such that each expanded lock is locatable using the index. The contention condition is resolved by distributing requests for acquiring and releasing the read access and write access to the resource by the several processes across the original lock and the set of expanded locks.

Description

technical field [0001] The present invention relates generally to an improved data processing system, and more particularly to a computer-implemented method, system, and computer-usable program code for a dual-mode read-write lock (DML). Background technique [0002] Processes performed in the data processing system read and write data associated with the various resources. Data files, memory locations, and addresses on disk are some examples of such resources. [0003] When processing performed in a data processing system must read data from or write data to a resource, the operating system must sequence and control read / write requests. This control is important in ensuring that multiple processes reading and writing requests to the same resource do not affect the data integrity of that resource. For example, one process should not be allowed to read data while another process is writing it. Multiple processes can be allowed to read the same data concurrently, but not co...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G06F9/46
CPCG06F9/52G06F9/46G06F9/06
Inventor J·B·穆迪B·米利
Owner IBM CORP
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