COMPLETE AND CONCISE REMOTE(CCR) DIRECTORY

摘要

PROBLEM TO BE SOLVED: To provide structure on a system for maintaining the coherence of a cache line in a common memory multiplexer system by permitting a shadow directory to contain state information on a local main memory cached in an outer common cache. SOLUTION: A shadow directory 40 contains only state information on a local main memory cached in an outer common cache. Respective shadow directories 40 contain plural sets 41 and the respective sets 41 contain plural items 42. The respective items 42 are the memory addresses of the local main memory. The respective items 42 contain the state bits of an existing bit P and a change bit M and a tag bit. The existing bit P shows whether one line in the local main memory is stored in the outer common cache and the change bit M shows whether the line of the local main memory is changed by the outer cache or not.