Dynamic management of snoop granularity for a coherent asynchronous DMA cache
US5526512A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 20, 1993 |
| Grant date | Jun 11, 1996 |
| Priority date | — |
| Expiry date | Sep 20, 2013 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F12/0835
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A system and method dynamically changes the snoop comparison granularity between a sector and a page, depending upon the state (active or inactive) of a direct memory access (DMA) I/O device which is writing to a device on the system bus asynchronously when compared to the CPU clock. By using page address granularity, erroneous snoop hits will not occur, since potentially invalid sector addresses are not used during the snoop comparison. Sector memory addresses may be in a transition state at the time when the CPU clock determines a snoop comparison is to occur, because this sector address has been requested by a device operating asynchronously with the CPU clock. Once the asynchronous device becomes inactive the system dynamically returns to a page and sector address snoop comparison granularity.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.