Cache coherency
Cache coherency (alternatively
cache coherence or
cache consistency) is the property that accessing a
cache gives the same value as the underlying data, even when the data was modified by a different process after the caching was performed. This is important for consistent operation of
multiprocessor (and is mimicked in
distributed shared memory systems) in which each
CPU has a non-shared cache of a shared
memory area. Cache coherence is special case of
memory coherence.
Various protocols have been devised for maintaining cache coherency, such as the MESI protocol, MSI protocol, MOSI protocol and the MOESI protocol. Most of the cache protocols in multiprocessors are supporting sequential consistency model.
See also: