System and method for maintaining ownership of a processor bus while sending a programmed number of snoop cycles to the processor cache
US6275885A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 30, 1998 |
| Grant date | Aug 14, 2001 |
| Priority date | — |
| Expiry date | Sep 30, 2018 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F13/16
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A computer is provided having a bus interface unit coupled between a CPU bus, a peripheral bus (i.e., PCI bus and/or graphics bus), and a memory bus. The bus interface unit includes controllers linked to the respective buses, and a plurality of queues placed within address and data paths between the various controllers. The peripheral bus controller can decode a write cycle to memory, and the processor controller can thereafter request and be granted ownership of the CPU local bus. The address of the write cycle can then be snooped to determine if valid data exists within the CPU cache storage locations. If so, a writeback operation can occur. Ownership of the CPU bus is maintained by the bus interface unit during the snooping operation, as well as during writeback and the request of the memory bus by the peripheral-derived write cycle. It is not until ownership of the memory bus is granted by the memory arbiter that mastership is terminated by the bus interface unit. Accordingly, the bus interface unit keeps CPU-derived cycles off the CPU bus to ensure memory arbiter grants ownership to a write cycle from the peripheral bus. In this fashion, data from the peripheral bus can be sto…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.