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Virtual Memory

  • Buddy System Allocator

    • Slab Allocator

  • memory-management unit (MMU)

Slab Allocator

一个Slab有一个或多个连续页，并划分成相同大小的对象

Three possible states:

  • Full: all objects are allocated
  • Partial: some objects are allocated, some are free
  • Empty: all objects are free

Virtual Addresses

Linux特性:

  • kernel使用virtual memory(但并非所有操作系统都一样)
  • 虚拟地址空间被划分，高位被kernel使用，低位被User使用

MMU

负责实现虚拟地址的硬件

File System Interface

File is a contiguous logical address space for storing information

File Attributes

文件系统：路径

Meta-data

Create： - Entry in directory

Open: - return a handler for other operations

read/write: need to maintain a pointer

delete: - Hardlink:maintain a counter

truncate:delete a dile but maintains its attributes

Per-process table: current location pointer, access rights

System-wide table : location on the disk

File Structure

解析者决定文件格式