Patent ID: 6970979
Filing Date: 2005-11-29
Classification: G06F

Abstract:
1. A computer system comprising: a plurality of active devices, wherein each active device includes a cache, wherein the plurality of active devices includes a first active device that includes a first cache; a directory configured to indicate which of the plurality of active devices has an ownership responsibility for a given coherency unit; an address network configured to convey address packets between the plurality of active devices and the directory, wherein the address network includes a response virtual network configured to convey response packets and a multicast virtual network configured to convey invalidating packets; a data network configured to convey data packets between the plurality of active devices; wherein the directory is configured to send a response packet to the first active device on the response virtual network and to send an invalidating packet to at least one of the plurality of active devices on the multicast virtual network; wherein the first active device is configured to transition an ownership responsibility for a first coherency unit cached in the first cache upon receipt of the response packet and to transition an access right to the first coherency unit cached in the first cache upon receipt of a corresponding data packet, wherein the ownership responsibility transitions at a different time than the access right transitions.