优化非易失内存的写活动感知页表管理策略

96 浏览量更新于2024-07-15 收藏 1.37MB PDF 举报

本文探讨了面向非易失性主存储器的写活动感知页表管理（Write-Activity-Aware Page Table Management，简称WAPTM）。非易失性内存技术如相变记忆（Phase Change Memory，PCM）和忆阻器因其低功耗和高密度的优势，被视为嵌入式系统中传统动态随机存取内存（DRAM）的潜在替代。然而，PCM的写入耐久性问题限制了其广泛应用，尤其是在作为频繁访问的主存储器组件时。 WAPTM的核心思想是通过重新设计系统软件和利用硬件对写入活动的识别能力，实现对页表管理的优化。这种方法旨在减少不必要的写入操作，从而降低对非易失性内存如PCM的压力，延长其使用寿命。在文章中，作者提出了一种简单且有效的策略，即在Google Android操作系统中，针对ARM架构实现WAPTM。他们选取真实的Android应用程序进行评估，结果显示WAPTM显著减少了页表中的写入次数，证实了这种策略的有效性和它在保护基于PCM的主存储器寿命方面的潜力。 WAPTM的具体实施包括以下关键步骤： 1. **系统软件调整**：通过对操作系统进行定制或修改，使得在必要时仅更新真正发生变化的数据项，而不是整个页表。这需要操作系统能够识别哪些数据的变化会导致页表索引的改变。 2. **硬件支持**：利用硬件提供的写入活动感知功能，比如在PCM等非易失性存储器中，某些技术可能允许检测到实际的写入事件，而非仅仅依赖于传统的刷新周期。 3. **页表管理算法**：设计智能的页表管理算法，根据实际写入活动动态调整页表布局，减少不必要的数据迁移和刷新操作。 4. **性能与耐用性的权衡**：尽管WAPTM旨在减少写入操作，但必须确保对性能的影响在可接受范围内，同时维持非易失性内存的稳定工作。通过实验证明，WAPTM不仅有助于提高PCM等非易失性存储器的使用效率，而且对于那些追求低功耗、长寿命和高存储密度的嵌入式系统设计具有显著的价值。随着非易失性存储技术的发展和成熟，WAPTM这类解决方案有望在未来内存管理系统中扮演重要角色。

Towards Write-Activity-Aware Page Table Management for Non-volatile Main Memories 34:5

Fig. 2. Architectures of DRAM- and PCM-based embedded systems.

In this work, we assume that hardware features [Lee et al. 2010; Yang et al. 2007; Cho

and Lee 2009] introduced in Section 1 are adopted, such that a bit ﬂip only happens

when the value to be written differs from the original value in the cell.

3.2. PCM-Based Embedded Systems

Current mainstream embedded systems use DRAM as main memory. As shown in Fig-

ure 2(a), the CPU transfers data and instructions to and from DRAM.

While the capac-

ity of DRAM keeps increasing, power consumption and density of DRAM are reaching

their limits [Xie 2011; Qureshi et al. 2009a, 2009b; Lee et al. 2009; Dhiman et al. 2009;

Zhou et al. 2009; Lee et al. 2010; Ferreira et al. 2010]. Emerging non-volatile memo-

ries have attracted extensive studies for replacing DRAM because of features such as

high-density and low-power consumption. Among various non-volatile memories, PCM

is one of the most promising to complement or replace DRAM in embedded systems.

There are already commercial PCM products available in the market [Micron 2012],

making it possible to build PCM-based embedded systems. As shown in Figure 2(b), a

PCM-based embedded system features PCM as its main memory. Software then needs

to manage and interact with PCM, instead DRAM.

3.3. Page Table Mapping

Most modern operating systems access and manage memory under the concept of

virtual memory [Silberschatz et al. 2008], which partitions the memory into ﬁxed-

sized blocks (page frames). The virtual memory is divided into pages, each of which

ﬁts exactly into one page frame. Logical addresses are translated into physical ones by

looking up per-process page tables, which are stored in multiple memory page frames.

Figure 3 presents a two-level page table design, in which a logical address is divided

into offsets in the Page Global Directory (PGD), page table, and page frame. A register

stores the base address of the PGD. Each PGD entry points to a page table which

consists of PTEs. A PTE stores the physical address of a page frame and ﬂag bits to

indicate page properties and states. For example, a 32bit ARM processor [ARM Limited

2005] uses the most signiﬁcant 20 bits to specify the address of a page frame and the

remaining bits to record properties such as whether the page is present in memory.

To access part of a page, the PGD base address is ﬁrst obtained from the register

(e.g, CR3 in Intel x86 architecture) [Intel Corporation 2013]. By adding the global

directory offset obtained from the logical address, the base address of the page table

Caching is omitted in Figure 2 for brevity.

ACM Transactions on Embedded Computing Systems, Vol. 14, No. 2, Article 34, Publication date: February 2015.

剩余22页未读，继续阅读

weixin_38590790

粉丝: 4
资源: 940

优化非易失内存的写活动感知页表管理策略

主存储器空间的分配和回收

行业文档-设计装置-存储器写辅助.zip

段页式存储器管理 段页式存储器管理 段页式存储器管理

什么是虚拟存储器？虚拟存储器有哪些特征？ 在请求式分页系统中，页表应增加哪些数据项？每项的作用是什么？ 直接写在下面，不需要附件。

简述虚拟存储器的工作原理

简要叙述页式虚拟存储器的地址翻译过程，虚地址、实地址的结构如何，页表及页表项的结构如何？。

分页存储管理属于哪一类内存管理方法

80286的内部结构、系统配置及存储器管理

计算机组成原理存储器实现

最新资源

段页式存储器管理段页式存储器管理段页式存储器管理

什么是虚拟存储器？虚拟存储器有哪些特征？在请求式分页系统中，页表应增加哪些数据项？每项的作用是什么？直接写在下面，不需要附件。