A Cache Fill and Migration Policy for STT-RAM-Based Multi-Level Hybrid Cache in 3D CMPs

Recently, in 3D Chip-Multiprocessors (CMPs), a hybrid cache architecture of SRAM and Non-Volatile Memory (NVM) is generally used to exploit high density and low leakage power of NVM and a low write overhead of SRAM. The conventional access policy does not consider the hybrid cache and cannot make good use of the characteristics of both NVM and SRAM technology. This paper proposes a Cache Fill and Migration policy (CFM) for multi-level hybrid cache. In CFM, data access was optimized in three aspects: Cache fill, cache eviction, and dirty data migration. The CFM reduces unnecessary cache fill, write operations to NVM, and optimizes the victim cache line selection in cache eviction. The results of experiments show that the CFM can improve performance by 24.1% and reduce power consumption by 18% when compared to conventional writeback access policy.