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:
Jul. 28, 1998
Filed:
Mar. 05, 1997
Dwain Alan Hicks, Pflugerville, TX (US);
Peichun Peter Liu, Austin, TX (US);
Michael John Mayfield, Austin, TX (US);
Rajinder Paul Singh, Austin, TX (US);
International Business Machines Corporation, Armonk, NY (US);
Abstract
A method and system of implementing a cache coherency mechanism for supporting a non-inclusive cache memory hierarchy within a data processing system is disclosed. In accordance with the method and system of the invention, the memory hierarchy includes a primary cache memory, a secondary cache memory, and a main memory. The primary cache memory and the secondary cache memory are non-inclusive. Further, a first state bit and a second state bit are provided within the primary cache, in association with each cache line of the primary cache. As a preferred embodiment, the first state bit is set only if a corresponding cache line in the primary cache memory has been modified under a write-through mode, while the second state bit is set only if a corresponding cache line also exists in the secondary cache memory. As such, the cache coherency between the primary cache memory and the secondary cache memory can be maintained by utilizing the first state bit and the second state bit in the primary cache memory.