Software managed byte-addressable hybrid memory systems consisting of DRAMs and NVMMs offer a lot of flexibility to design efficient large scale data processing applications. Operating systems (OS) play an important role in enabling the applications to realize the integrated benefits of DRAMs' low access latency and NVMMs' large capacity along with its persistent characteristics. In this paper, we comprehensively analyze the performance of conventional OS physical memory management subsystems that were designed only based on the DRAM memory characteristics in the context of modern hybrid byte-addressable memory systems. To study the impact of high access latency and large capacity of NVMMs on physical memory management, we perform an extensive evaluation on Linux with Intel's Optane NVMM. We observe that the core memory management functionalities such as page allocation are negatively impacted by high NVMM media latency, while functionalities such as conventional fragmentation management are rendered inadequate. We also demonstrate that certain traditional memory management functionalities are affected by neither aspects of modern NVMMs. We conclusively motivate the need to overhaul fundamental aspects of traditional OS physical memory management in order to fully exploit terabyte-scale NVMMs.

翻译：由DRAM和非易失性内存（NVMM）组成的软件管理字节可寻址混合内存系统，为设计高效的大规模数据处理应用提供了极大灵活性。操作系统在帮助应用实现DRAM低访问延迟与NVMM大容量及持久特性的协同优势中扮演关键角色。本文系统分析了传统仅基于DRAM内存特性设计的操作系统物理内存管理子系统，在现代混合字节可寻址内存系统背景下的性能表现。为探究NVMM高访问延迟与大容量对物理内存管理的影响，我们基于英特尔Optane NVMM在Linux上进行了广泛评估。研究发现：核心内存管理功能（如页分配）受NVMM高介质延迟的负面影响显著，而传统碎片管理等功能则显露出不足。同时我们也证明，某些传统内存管理功能并未受到现代NVMM两方面特性的影响。最终我们得出结论，为充分挖掘太字节级NVMM的潜力，需对传统操作系统物理内存管理的根本性架构进行重构。