BACKGROUND Malicious code, known as malware, which includes viruses, worms, adware, etc., may attack core components of the operating system to compromise key applications, including critical applications that operate in the operating system kernel,…

A processor including a virtualization system of the processor with a memory virtualization support system to map a reference to guest-physical memory made by guest software executable on a virtual machine which in turn is executable on a host machin…

BACKGROUND Many computer systems utilize virtualized memory for security, stability and/or other purposes. In various virtualized-memory systems, a virtual machine monitor ("VMM") may control direct use of memory and/or computer processors in a…

A system and method for accessing memory are provided. The system comprises a lookup buffer for storing one or more page table entries, wherein each of the one or more page table entries comprises at least a virtual page number and a physical page nu…

原文作者:Gustavo Duarte 原文地址:http://duartes.org/gustavo/blog/post/what-your-computer-does-while-you-wait Page Cache, the Affair Between Memory and Files 工作于内存和文件之间的页缓存 Previously we looked at how the kernel manages virtual memory for a user process, but…

原文标题:Page Cache, the Affair Between Memory and Files 原文地址:http://duartes.org/gustavo/blog/ [注:本人水平有限,只好挑一些国外高手的精彩文章翻译一下.一来自己复习,二来与大家分享.] 上次我们考察了内核如何为一个用户进程管理虚拟内存,但是没有涉及文件及I/O.这次我们的讨论将涵盖非常重要且常被误解的文件与内存间关系的问题,以及它对系统性能的影响. 提到文件,操作系统必须解决两个重要的问题.首先是硬盘驱动器的…

To translate a virtual address into a physical one, the CPU must take the contents of each level field, convert it into an offset into the physical page containing the Page Table and read the PFN of the next level of Page Table. This is repeated thre…

逻辑地址与物理地址的转化 页表是由页表项(PTE)组成的数组.512个PTE构成一个页表页(Page-table page). PTE中包含了物理页码(PPN physical page number)以及一些标志,来控制物理空间块的读写访问权限. 物理地址与虚拟地址的映射为三层树形结构,每一层存储下一层页表页的地址,最后一层存储物理地址的PTE. (个人理解:计算机中的物理地址被逻辑性理解成了页面+偏移量,其本质没发生变化,依旧是某一内存单元的编号) ​ 图 PTE的格式 代码解析 walk函…

BACKGROUND Advances in semi-conductor processing and logic design have permitted an increase in the amount of logic that may be present on integrated circuit devices. As a result, computer system configurations have evolved from a single or multiple…

Previously we looked at how the kernel manages virtual memory for a user process, but files and I/O were left out. This post covers the important and often misunderstood relationship between files and memory and its consequences for performance. Two…