Cache reuse control system having reuse information field in each cache entry to indicate whether data in the particular entry has higher or lower probability of reuse

摘要

A control system for a cache provided between a central processing unit and a main memory. The control system includes a plurality of entries each having a data area and a control information area. A reuse information field in the control information area is set at the same time as a load/store instruction from the central processing unit. When the central processing unit issues an access instruction to desired data in the main memory, an entry storing the desired data to be accessed is searched from a plurality of entries of the cache. If the desired data is not present in any of the plurality of entries, the desired data is read from the main memory. Then, an empty entry is searched from the plurality of entries. If there is no empty entry, an entry is selected which is not set with the reuse information in the control information area of the entry, the reuse information instructing to preferentially maintaining the data in the data field of the entry. The data of the selected entry is replaced by the data read from the main memory. Reuse information in an access command from the central processing unit for maintaining data in a particular entry is set to the reuse information field.