Instruction fetching

Abstract

There is provided an apparatus, a method, a chip containing product, a system and a medium. The apparatus is provided with an instruction fetch queue for storage of instruction fetch entries, and prefetching circuitry configured, for each instruction fetch entry and in response to a determination that a block of instructions indicated by that instruction fetch entry is not present in instruction storage circuitry, to issue a request to fetch the block and to cause the block to be allocated to the instruction storage circuitry. The apparatus is also provided with control circuitry configured to suppress issuing the request in response to a number of outstanding requests meeting or exceeding a variable throttling threshold. The control circuitry is configured to derive the variable throttling threshold from properties of previously fetched blocks, the properties determined before or during storage of the previously fetched blocks in the instruction storage circuitry.