Cache memory system and method for managing the same

Abstract

A cache memory system reduces the rate of cache misses. The cache memory system includes a first auxiliary storage device which stores first information blocks and a second auxiliary storage device which stores second information blocks fetched from a lower level memory device. Each second block includes a plurality of the first information blocks. A process for fetching information selectively fetches a first or second information block from the lower level memory device and selectively stores the fetched block in the first auxiliary storage device and/or the second auxiliary storage device. Selection of the size of block to fetch and where to store the fetched block is according to whether the data to be referenced by the central controller is in the first auxiliary storage device or the second auxiliary storage device and whether first information blocks that do not include the referenced data are both in the second information block including the referenced data and in the first auxiliary storage device. A control unit that controls the selective fetching and storing maintains state data that includes entries corresponding to second information blocks. Each entry identifies a corresponding second information block and indicates the number of first information blocks that are in the first auxiliary storage device and from the corresponding second information block.