An apparatus and method for implementing a shared unified cache. For example, one embodiment of a processor comprises: a plurality of processor cores grouped into modules, wherein each module has at least two processor cores grouped therein; a plurality of level 1 (L1) caches, each L1 cache directly accessible by one of the processor cores; a level 2 (L2) cache associated with each module, the L2 cache directly accessible by each of the processor cores associated with its respective module; a shared unified cache to store data and/or instructions for each of the processor cores in each of the modules; and a cache management module to manage the cache lines in the shared unified cache using a first cache line eviction policy favoring cache lines which are shared across two or more modules and which are accessed relatively more frequently from the modules.