The design of an efficient swap mechanism for hybrid DRAM-NVM systems

Non-Volatile Memory (NVM) is becoming an attractive candidate to be the swap area in embedded systems for its near- DRAM speed, low energy consumption, high density, and byte-addressability. Swapping data from DRAM out to NVM, however, can cause large performance/energy penalty and deplete the lifetime of NVM. Traditional swap mechanisms may need to be re-studied. Even through there are several swap mechanisms proposed for the hybrid DRAMNVM systems, most of them have limited performance without considering the data access features of applications. In this paper, we analyze the data accesses features of different applications. Then, a swap mechanism, called Refinery Swap, is proposed to improve the performance of the system, reduce energy consumption, and increase the lifetime of NVM simultaneously. Refinery Swap presented two algorithms to exploit the data access features of applications and the characteristics of different kinds of memory medias. The swap operations in the system and the writes upon NVM are reduced using Refinery Swap. Extensive experiments are conducted with standard benchmarks. The experimental results show that the lifetime of NVM for the system with Refinery Swap can be 83 times that of Linux Swap. The performance of the system with Refinery Swap can be 17 times that of DR.Swap, the state-of-theart swap mechanism for hybrid memory embedded systems. Moreover, the energy consumption of the system achieves 17 times lower.