Hybrid cache having physical-cache and virtual-cache characteristics and method for accessing same
US5479630A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Mar 11, 1994 |
| Grant date | Dec 26, 1995 |
| Priority date | — |
| Expiry date | Mar 11, 2014 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F12/0848
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A cache memory system includes a primary cache characterized by a virtual index and physical tags, and a secondary cache characterized by a physical index and physical tag. Thus, the cache system forms a hybrid of physical-cache and virtual-cache characteristics. Further, the secondary cache includes a primary index segment for each line of secondary cache. The primary index segment corresponds to a portion of the virtual address for the contents stored at the respective secondary-cache line. Further, primary cache is maintained as a subset of secondary cache. To maintain the primary cache in such a way, the primary index segment is used to generate an index into primary cache to identify each potential primary-cache block which may be a subset of a secondary-cache block to be changed. When a secondary-cache block is to be invalidated, flushed or overwritten, the corresponding primary-cache blocks are identified and invalidated. The primary index segment also serves as a virtual tag for assuring that at any given time primary cache stores no more than one valid block corresponding to the same physical locations. When a secondary-cache hit occurs in response to a secondary-cache phy…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.