| 摘要 |
PROBLEM TO BE SOLVED: To improve the performance of access to a cache by decreasing the request of a state change to another system by fractionizing the state of managing data blocks on the cache. SOLUTION: A cache controller 18 expresses the state of data blocks in six states newly adding write enable W to invalid I, shared S, exclusive E, modify M and sharing change O. Corresponding to a fetch request from the CPU of a present system to the data block on the invalid state I, when the data block in the modified state M is acquired from the cache device of another system, the cache controller 18 changes the state of the acquired data block from invalid I to write enable W, switches the state of the data block at the destination of acquisition from modify M to invalid I and unnecessitates a state change notice to the other system by the next store request of the present CPU.
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