ALLOCATION AND WRITE POLICY FOR A GLUELESS AREA-EFFICIENT DIRECTORY CACHE FOR HOTLY CONTESTED CACHE LINES

Methods and apparatus relating to allocation and/or write policy for a glueless area-efficient directory cache for hotly contested cache lines are described. In one embodiment, a directory cache stores data corresponding to a caching status of a cache line. The caching status of the cache line is stored for each of a plurality of caching agents in the system. An write-on-allocate policy is used for the directory cache by using a special state (e.g., snoop-all state) that indicates one or more snoops are to be broadcasted to all agents in the system. Other embodiments are also disclosed.