System with a directory based coherency protocol and split ownership and access right coherence mechanism

摘要

Various systems and methods for using a directory based coherency protocol in a system that employs a split ownership and access right cache coherence mechanism are disclosed. A computer system may include a directory, several active devices configured to access data, an address network configured to convey coherence requests point-to-point between the active devices and the directory, and a data network configured to convey data between the active devices. Each active device includes a cache configured to store data accessed by that active device. An ownership responsibility and an access right associated with a first coherency unit in a first cache transition at different times.