L2 cache controller with slice directory and unified cache structure

Abstract

A cache memory logically partitions a cache array having a single access/command port into at least two slices, and uses a first cache directory to access the first cache array slice while using a second cache directory to access the second cache array slice, but accesses from the cache directories are managed using a single cache arbiter which controls the single access/command port. In the illustrative embodiment, each cache directory has its own directory arbiter to handle conflicting internal requests, and the directory arbiters communicate with the cache arbiter. An address tag associated with a load request is transmitted from the processor core with a designated bit that associates the address tag with only one of the cache array slices whose corresponding directory determines whether the address tag matches a currently valid cache entry. The cache array may be arranged with rows and columns of cache sectors wherein a given cache line is spread across sectors in different rows and columns, with at least one portion of the given cache line being located in a first column having a first latency and another portion of the given cache line being located in a second column having a second latency greater than the first latency. The cache array outputs different sectors of the given cache line in successive clock cycles based on the latency of a given sector.