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coherence protocol

The rules caches follow to keep their copies of a line in agreement, by tracking a state for each line and messaging each other.

A coherence protocol is the per-line state machine and message set (snooping broadcasts or directory lookups) by which caches grant read and write permission; MESI and its extensions MOESI (AMD) and MESIF (Intel) are the common ones.

See also

MESI protocol snooping
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