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12. Hierarchical Page Tables

Hierarchical page tables are introduced as an optimal solution for page table management, helping to efficiently allocate memory for processes. The transition from single to multi-level page tables is essential for efficiently managing large addresses, particularly in 64-bit systems. Further techniques like hashed and inverted page tables are examined as advanced methods to minimize memory usage and enhance performance.

Sections

Hierarchical Page Tables

Hierarchical page tables offer an efficient way to manage memory by organizing page tables in multiple levels.

12.1 Section Overview

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12.1.1 Introduction to Page Table Length Register

This section introduces the concept of the Page Table Length Register (PTLR) and its significance in managing memory via hierarchical page tables.

12.1.2 Segmentation and Separate Page Tables

This section discusses hierarchical page tables, segmentation, and other methods of managing memory address spaces to optimize page table sizes.

12.1.3 Hierarchical Page Tables Overview

This section outlines hierarchical page tables, a method used to effectively reduce the size of page tables in operating systems by utilizing multiple levels of page tables.

12.1.4 Two-Level Page Table Scheme

The Two-Level Page Table Scheme is an efficient way to manage memory in computer systems, enhancing the traditional page table method by introducing multiple levels to minimize the overall size of page tables.

12.1.5 Three-Level Page Table Discussion

This section discusses hierarchical page tables, specifically three-level page tables, and their importance in managing virtual memory efficiently.

Hashed Page Tables

Hashed page tables are used to efficiently manage memory address translation for larger address spaces, particularly in 64-bit systems.

12.2 Section Overview

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12.2.1 Introduction to Hashed Page Tables

This section introduces hashed page tables, a method used to manage page tables for large address spaces efficiently, specifically for 64-bit computers.

12.2.2 Structure of a Hashed Page Table

This section discusses hierarchical page tables and introduces the concept of hashed page tables as a mechanism to manage large address spaces effectively.

12.2.3 Searching in Hashed Page Tables

This section explores hierarchical page tables and hashed page tables, highlighting their mechanisms and advantages over traditional methods.

Inverted Page Table

This section introduces the concept of inverted page tables, which track physical pages instead of virtual pages, reducing memory usage and improving efficiency.

12.3 Section Overview

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12.3.1 Overview of Inverted Page Table

Inverted page tables track physical pages instead of logical pages, reducing memory overhead at the cost of increased lookup time.

12.3.2 Advantages and Disadvantages

This section explores the advantages and disadvantages of various paging techniques, focusing on hierarchical page tables, hashed page tables, and inverted page tables.

12.3.3 Using Hash Tables with Inverted Page Tables

This section discusses the use of hierarchical page tables, specifically focusing on hashed page tables and inverted page tables to optimize memory management in computer systems.

Example of Page Table Calculation

This section covers hierarchical page tables, segmentation, and the mechanics of hashed and inverted page tables used in virtual memory management systems.

12.4 Section Overview

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12.4.1 Setup of the Example Problem

This section discusses hierarchical page tables as a method for reducing the size of page tables in memory management.

12.4.2 Calculating Page Table Sizes

This section outlines methods for reducing page table sizes, including hierarchical and hashed page tables.

12.4.3 Final Calculation of Page Size

This section explains how hierarchical page tables are used to effectively manage page sizes in virtual memory management.

Learning Objectives

  • Hierarchical page tables allow for more efficient memory allocation by reducing the overall size of page tables.

  • Multi-level page tables are crucial for managing large address spaces, especially in modern computing systems.

  • Hash tables and inverted page tables serve to optimize the performance of page table lookups and reduce memory overhead.

Key Concepts

Hierarchical Page Tables

A method of structuring page tables that allows the use of multiple levels to reduce memory usage.

Multilevel Page Tables

A page table organization method where the page number is split into multiple parts, each indexing different levels of page tables.

Hashed Page Tables

A technique that uses a hash function to map virtual page numbers into addresses in a page table, facilitating quicker access.

Inverted Page Table

An organization of the page table that keeps track of physical memory pages instead of logical pages, optimizing memory usage.

Practice Exercises

Total Questions

2

Estimated Time

4 min

Passing Score

70%

Instructions

  • Read each question carefully
  • You can use hints if you need help
  • Complete all questions before submitting