Several emerging technologies for byte-addressable non-volatile memory (NVM) have been considered to replace DRAM as the main memory in computer systems during the last years. The disadvantage of a lower write endurance, compared to DRAM, of NVM technologies like Phase-Change Memory (PCM) or Ferroelectric RAM (FeRAM) has been addressed in the literature. As a solution, in-memory wear-leveling techniques have been proposed, which aim to balance the wear-level over all memory cells to achieve an increased memory lifetime. Generally, to apply such advanced aging-aware wear-leveling techniques proposed in the literature, additional special hardware is introduced into the memory system to provide the necessary information about the cell age and thus enable aging-aware wear-leveling decisions. This paper proposes software-only aging-aware wear-leveling based on common CPU features and does not rely on any additional hardware support from the memory subsystem. Specifically, we exploit the memory management unit (MMU), performance counters, and interrupts to approximate the memory write counts as an aging indicator. Although the software-only approach may lead to slightly worse wear-leveling, it is applicable on commonly available hardware. We achieve page-level coarse-grained wear-leveling by approximating the current cell age through statistical sampling and performing physical memory remapping through the MMU. This method results in non-uniform memory usage patterns within a memory page. Hence, we further propose a fine-grained wear-leveling in the stack region of C / C++ compiled software. By applying both wear-leveling techniques, we achieve up to $78.43\%$ of the ideal memory lifetime, which is a lifetime improvement of more than a factor of $900$ compared to the lifetime without any wear-leveling.

中文翻译：

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SoftWear：非易失性主内存的纯软件内存磨损均衡

在过去的几年中，一些用于字节可寻址非易失性存储器 (NVM) 的新兴技术已被考虑取代 DRAM 作为计算机系统中的主存储器。与 DRAM 相比，NVM 技术（如相变存储器 (PCM) 或铁电 RAM (FeRAM)）的写入耐久性较低的缺点已在文献中得到解决。作为一种解决方案，已经提出了内存磨损均衡技术，旨在平衡所有存储单元的磨损水平，以实现更长的内存寿命。通常，为了应用文献中提出的这种先进的老化感知磨损均衡技术，将额外的特殊硬件引入存储系统，以提供有关单元年龄的必要信息，从而实现老化感知磨损均衡决策。本文提出了基于常见 CPU 特性的纯软件老化感知磨损均衡技术，并且不依赖于来自内存子系统的任何额外硬件支持。具体来说，我们利用内存管理单元 (MMU)、性能计数器和中断来近似内存写入计数作为老化指标。尽管纯软件方法可能会导致磨损均衡稍差，但它适用于常用硬件。我们通过统计采样近似当前单元年龄并通过 MMU 执行物理内存重新映射来实现页面级粗粒度磨损均衡。此方法会导致内存页内的内存使用模式不一致。因此，我们进一步提出了在 C/C++ 编译软件的堆栈区域中的细粒度磨损均衡。通过应用两种磨损均衡技术，