The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Nov. 23, 2004
Filed:
Jan. 10, 2000
Paul E. McKenney, Beaverton, OR (US);
Brent Kingsbury, Beaverton, OR (US);
International Business Machines Corporation, Armonk, NY (US);
Abstract
A reader-writer lock minimizes writer and reader overhead by employing lock structures that are shared among groups of processors that have lower latencies. In the illustrated multiprocessor system having a non-uniform memory access (NUMA) architecture, each processor node has a lock structure comprised of a shared counter and associated flag for each CPU group. During a read, the counter can be changed only by processors within a CPU group performing a read. This reduces the reader overhead that otherwise would exist if all processors in the system shared a single counter. During a write, the shared flag can be changed by a process running on any processor in the system. The processors in a CPU group are notified of the write through the shared flag. This reduces the writer overhead that otherwise would exist if each processor in the system had a separate flag. The number of CPUs per group can be varied to optimize performance of the lock in different multiprocessor systems.