A cache is configured to receive direct access transactions. Each direct access
transaction explicitly specifies a way of the cache. The cache may alter the state
of its replacement policy in response to a direct access transaction explicitly
specifying a particular way of the cache. The state may be altered such that a
succeeding cache miss causes an eviction of the particular way. Thus, a direct
access transaction may be used to provide a deterministic setting to the replacement
policy, providing predictability to the entry selected to store a subsequent cache
miss. In one embodiment, the replacement policy may be a pseudo-random replacement
policy. In one embodiment, a direct access transaction also explicitly specifies
a cache storage entry to be accessed in response to the transaction. The cache
may access the cache storage entry (bypassing the normal tag comparisons and hit
determination used for memory transactions) and either read the data from the cache
storage entry (for read transactions) or write data from the transaction to the
cache storage entry (for write transactions). Other embodiments may set the replacement
policy based on other types of transactions.