Patent ID: 7028159

Claim:
A processing device for controlling two hierarchical level data caches, comprising: a processor which executes a prefetch instruction included as one of a plurality of instructions of a program in a main memory which is external of said processing device; a memory interface unit which accesses said main memory; an internal cache controlled as a first level cache; and a cache control function which controls an external cache external of said processing device as a second level cache, wherein said prefetch instruction, when executed, causes said processor to selectively perform, prior to executing a subsequent load instruction, one of a plurality of prefetch operation including transferring a certain quantity of operand data to be used in the subsequent load instruction from said main memory to both the first and second level caches, and transferring a certain quantity of operand data to be used in the subsequent load instruction from said main memory to the second level cache only, and wherein said prefetch instruction includes a plurality of indication bits for specifying cache levels to which said operand data is to be transferred and for specifying a quantity of said operand data to be transferred from said main memory.