Apple Inc.
Snapshot arbitration techniques for memory requests

Abstract:

Techniques are disclosed relating to arbitration for computer memory resources. In some embodiments, an apparatus includes queue circuitry that implements multiple queues configured to queue requests to access a memory bus. Control circuitry may, in response to detecting a first threshold condition associated with the queue circuitry, generate a first snapshot that indicates numbers of requests in respective queues of the multiple queues at a first time. The control circuitry may generate a second snapshot that indicates numbers of requests in respective queues of the multiple queues at a second time that is subsequent to the first time. The control circuitry may arbitrate between requests from the multiple queues to select requests to access the memory bus, where the arbitration is based on snapshots to which requests from the multiple queues belong. Disclosed techniques may approximate age-based scheduling while reducing area and power consumption.