CACHE COHERENCY PROTOCOL INCLUDING HOVERING(H) STATE HAVING STRICT MODE AND NONSTRICT MODE

摘要

PROBLEM TO BE SOLVED: To obtain an improved method for maintaining data coherency by determining whether or not a 1st cache should be updated according to the operation mode of the 1st cache in response to the detection of data transfer to remotely sent and including a 2nd data item. ;SOLUTION: A L2 cache 14 includes a cache controller 36. The cache controller 36 manages the storage and retrieval of data in a data array 34 and manages the update of a cache directory 32 in response to a signal received from a relative L1 cache and transaction snooped through an interconnection line. Then, a read request is put in an entry in a read queue 50. The cache controller 36 services the read request by supplying requested data to the relative L1 cache and then, removes the read request from the read queue 50.;COPYRIGHT: (C)1999,JPO