Method and apparatus for operating an age queue for memory request operations in a processor of an information handling system

Abstract

A processor includes a processor core with a core interface unit that includes an age queue and a request queue. The core interface unit receives load requests from the processor core. The request queue stores the requests in respective slots of the request queue. The age queue stores ID tags in respective age queue slots. Each ID tag in the age queue corresponds to a respective address of a load instruction in the request queue. In one embodiment, ID tags propagate through the age queue at a fixed rate of two at a time from a tail of the age queue to a head of the age queue. Arbitration control circuitry generates an enable bit vector that identifies the oldest ID tag in the age queue corresponding to the oldest load request in the request queue. The arbitration circuitry selects the identified oldest instruction in the request queue as the next to dispatch. In one embodiment, the core interface unit exhibits an input frequency that is a multiple of an internal operating frequency of the core interface unit.