An apparatus and method for implementing a heterogeneous memory subsystem is described. For example, one embodiment of a processor comprises: memory mapping logic to subdivide a system memory space into a plurality of memory chunks and to map the memory chunks across a first memory and a second memory, the first memory having a first set of memory access characteristics and the second memory having a second set of memory access characteristics different from the first set of memory access characteristics; and dynamic remapping logic to swap memory chunks between the first and second memories based, at least in part, on a detected frequency with which the memory chunks are accessed.