A heterogeneous memory system is implemented using a low-latency near memory (NM) and a high-latency far memory (FM). Pages in the memory system include NM blocks stored in the NM and FM blocks stored in the FM. A page is assigned to a region in the memory system based on the proportion of NM blocks in the page. When accessing a block, the block address is used to determine a region of the memory system, and a block offset is used to determine whether the block is stored in NM or FM. The memory system may observe memory accesses to determine the access statistics of the page and the block. Based on a page's hotness and access density, the page may be migrated to a different region. Based on a block's hotness, the block may be migrated between NM and FM allocated to the page.