Recent advances in memory technology, memory hierarchy is becoming diverse with performance-differentiated memory such as high bandwidth memory (HBM) and non-volatile memory (NVM) in modern computer systems. However, the current memory placement has been designed with the assumption that all the memory has the same capabilities based on DRAM. In this letter, we analyze memory placement schemes in state-of-the-art Linux systems to the hardware-assisted tiered memory system. Our analysis is conducted on the real system equipped with Intel's Optane Persistent Memory, enabling tiered memory with DRAM (fast) and Optane (slow) memory. We observe that tiered memory augmented on traditional NUMA form do not exhibit that accessing the local memory provides better performance than that of the remote memory because local Optane memory is slower than remote DRAM. Due to this distinct characteristic, there are several inefficiencies in the commodity operating systems. To make use of tiered memory systems efficiently, this paper explores the design space of practical software solutions, which can be currently applicable in the Linux system.

中文翻译：

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硬件辅助分层存储系统上的内存放置研究

内存技术的最新进展，随着现代计算机系统中性能差异化的内存，如高带宽内存 (HBM) 和非易失性内存 (NVM)，内存层次结构变得多样化。然而，当前的内存布局是在假设所有内存都具有基于 DRAM 的相同功能的情况下设计的。在这封信中，我们分析了最先进的 Linux 系统中的内存放置方案到硬件辅助的分层内存系统。我们的分析是在配备英特尔 Optane Persistent Memory 的真实系统上进行的，该系统支持具有 DRAM（快速）和 Optane（慢速）内存的分层内存。我们观察到，在传统 NUMA 形式上增强的分层内存并没有表现出访问本地内存比远程内存提供更好的性能，因为本地 Optane 内存比远程 DRAM 慢。由于这种独特的特性，商品操作系统存在一些效率低下的问题。为有效利用分层内存系统，本文探讨了目前可适用于Linux系统的实用软件解决方案的设计空间。