Apple Inc.
Establishing dependency in a resource retry queue

Abstract:

A memory cache controller includes a transaction arbiter circuit and a retry queue circuit. The transaction arbiter circuit may determine whether a received memory transaction can currently be processed by a transaction pipeline. The retry queue circuit may queue memory transactions that the transaction arbiter circuit determines cannot be processed by the transaction pipeline. In response to receiving a memory transaction that is a cache management transaction, the retry queue circuit may establish a dependency from the cache management transaction to a previously stored memory transaction in response to a determination that both the previously stored memory transaction and the cache management transaction target a common address. Based on the dependency, the retry queue circuit may initiate a retry, by the transaction pipeline, of one or more of the queued memory transactions in the retry queue circuit.