Directory-based coherence protocol allowing efficient dropping of clean-exclusive data
US5680576A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | May 5, 1995 |
| Grant date | Oct 21, 1997 |
| Priority date | — |
| Expiry date | May 5, 2015 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F12/0813
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A multiprocessor system having a plurality of requestors, a memory and memory directory controller employing directory-based coherence. The system implements a method to detect dropping of clean-exclusive data. Only one intervention message is permitted to target an exclusive object held by a first requestor, wherein the intervention message is caused by a second requestor. The system detects whether the first requestor has an outstanding writeback for the object targeted by the intervention message, as well as whether the first requestor has a clean-exclusive, dirty-exclusive or invalid copy of the object targeted by the intervention message. A clean-exclusive copy of the object has been dropped when no outstanding writeback is detected and the first requestor has the object in the invalid state.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.