Virtual Memory

Introduction

Virtual memory is a memory management technique that provides an idealized abstraction of the storage resources that are actually available on a given machine.

Address Translation

Key components of address translation:

• Page Tables
  • Page Table Entries (PTEs)
  • Page Table Base Register (PTBR)
  • Translation Lookaside Buffer (TLB)
• Address Spaces
  • Virtual Address Space
  • Physical Address Space

Page Management

Important page management concepts:

• Page Replacement Algorithms
  • FIFO (First In First Out)
  • LRU (Least Recently Used)
  • Clock Algorithm
  • Optimal Page Replacement
• Page Fault Handling
  • Page Fault Interrupt
  • Page Fault Service Routine
  • Page Replacement

Memory Protection

Memory protection mechanisms:

• Page Protection Bits
• Read/Write Permissions
• User/Kernel Mode Separation
• Memory Access Control

Important Concepts