1. A processor comprising: processor cores including heterogeneous processor cores, the heterogeneous processor cores comprising multiple central processing unit (CPU) cores; and a first cache connected to and shared by a first set of the processor cores; a second cache connected to and shared by a second set of the processor cores, the second cache being connected to the first cache; wherein at least the first set of processor cores and the first cache are integrated on a single integrated die; and wherein the first cache and second cache are kept coherent.