Emerging byte-addressable non-volatile memory (NVM) technologies offer higher density and lower cost than DRAM, at the expense of lower performance and limited write endurance. There have been many studies on hybrid NVM/DRAM memory management in a single physical server. However, it is still an open problem on how to manage hybrid memories efficiently in a distributed environment. This paper proposes Alloy, a memory resource abstraction and data placement strategy for an RDMA-enabled distributed hybrid memory pool (DHMP). Alloy provides simple APIs for applications to utilize DRAM or NVM resource in the DHMP, without being aware of the hardware details of the DHMP. We propose a hotness-aware data placement scheme, which combines hot data migration, data replication and write merging together to improve application performance and reduce the cost of DRAM. We evaluate Alloy with several micro-benchmark workloads and public benchmark workloads. Experimental results show that Alloy can significantly reduce the DRAM usage in the DHMP by up to 95%, while reducing the total memory access time by up to 57% compared with the state-of-the-art approaches.

新兴的字节可寻址非易失性存储器（NVM）技术比DRAM提供更高的密度和更低的成本，但以降低性能和有限的写入耐久性为代价。对于单个物理服务器中的混合NVM / DRAM内存管理，已有许多研究。然而，如何在分布式环境中有效地管理混合存储器仍然是一个悬而未决的问题。本文提出了Alloy，一种用于启用RDMA的分布式混合内存池（DHMP）的内存资源抽象和数据放置策略。合金提供了简单的API应用程序能够利用在DRAM或NVM资源DHMP，而不知道的硬件细节DHMP。我们提出了一种热感知数据放置方案，该方案将热数据迁移，数据复制和写入合并结合在一起，以提高应用程序性能并降低DRAM的成本。我们用几种微基准工作负载和公共基准工作负载评估Alloy。实验结果表明，与最新技术相比，Alloy可以显着减少DHMP中DRAM的使用率达95％，同时将总存储器访问时间减少多达57％。