Advanced Micro Devices, Inc.
METHOD AND APPARATUS FOR REDUCING THE LATENCY OF LONG LATENCY MEMORY REQUESTS

Abstract:

Systems, apparatuses, and methods for efficiently processing memory requests are disclosed. A computing system includes at least one processing unit coupled to a memory. Circuitry in the processing unit determines a memory request becomes a long-latency request based on detecting a translation lookaside buffer (TLB) miss, a branch misprediction, a memory dependence misprediction, or a precise exception has occurred. The circuitry marks the memory request as a long-latency request such as storing an indication of a long-latency request in an instruction tag of the memory request. The circuitry uses weighted criteria for scheduling out-of-order issue and servicing of memory requests. However, the indication of a long-latency request is not combined with other criteria in a weighted sum. Rather, the indication of the long-latency request is a separate value. The circuitry prioritizes memory requests marked as long-latency requests over memory requests not marked as long-latency requests.