Method and apparatus for calculating a page table index from a virtual address
US6393544B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Oct 31, 1999 |
| Grant date | May 21, 2002 |
| Priority date | — |
| Expiry date | Oct 31, 2019 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F2212/652
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A method and apparatus calculate a page table index from a virtual address. Employs a combined hash algorithm that supports two different hash page table configurations. A “short format” page table is provided for each virtual region, is linear, has a linear entry for each translation in the region, and does not store tags or chain links. A single “long format” page table is provided for the entire system, supports chained segments, and includes hash tag fields. The method of the present invention forms an entry address from a virtual address, with the entry address referencing an entry of the page table. To form the entry address, first a hash page number is formed from the virtual address by shifting the virtual address right based on the page size of the region of the virtual address. If the computer system is operating with long format page tables, the next step is to form a hash index by combining the hash page number and the region identifier referenced by the region portion of the virtual address, and to form a table offset by shifting the hash index left by K bits, wherein each long format page table entry is 2K bytes long. However, if the computer s…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.