Patent ID: 7437513

Claim:
A set-associative cache memory, comprising: a plurality of ways, each of which can be selectively operated or halted; a hit determination unit for determining hit ways for which cache access hits have occurred; a way number increase/decrease determination unit for: managing, for each of the ways that are being operated, the order of ways beginning from the way for which the time of use is most recent to the way for which the time of use is oldest; finding the order of said hit ways that have been obtained by said hit determination unit; counting the number of hits for each rank of said order; and determining increase or decrease of the number of operated ways based on an access pattern that is indicated by the relation of the number of hits for each of said ranks in said order; and a way number control unit for selecting operation or halting of operation of each of said ways according to the determination to increase or decrease the number of operated ways.