Virtual Memory

Characteristics of Paging and Segmentation

Process Execution

Process Execution (cont.)

Advantages of Partial Loading

Virtual Memory: large as you wish!

Virtual Memory (cont.)

Possibility of trashing

Locality and Virtual Memory

Support Needed for
Virtual Memory

Paging

Paging

Page Table Structure

Address Translation in a Paging System

Sharing Pages

Sharing Pages: a text editor

Translation Lookaside Buffer

Translation Lookaside Buffer

Use of a Translation Lookaside Buffer

TLB: further comments

Page Tables and Virtual Memory

Multilevel Page Tables

Windows NT Virtual Memory

Windows NT Virtual Memory

Windows NT Virtual Memory

The Page Size Issue

The Page Size Issue

The Page Size Issue

The Page Size Issue

Segmentation

Address Translation in a Segmentation System

Segmentation: comments

Sharing in Segmentation Systems

Sharing of Segments: text editor example

Combined Segmentation and Paging

Address Translation in a (simple) combined Segmentation/Paging System

Simple Combined Segmentation and Paging

Operating System Software

Fetch Policy

Placement policy

Replacement Policy

Replacement Policy

Replacement Policy

Basic algorithms for the replacement policy

The LRU Policy

Implementation of the LRU Policy

The FIFO Policy

Comparison of FIFO with LRU

The Clock Policy

The Clock Policy: an example

Comparison of Clock with FIFO and LRU

Comparison of Clock with FIFO and LRU

Page Buffering

Page Buffering

Cleaning Policy

Cleaning Policy

Resident Set Size

Resident Set Size

Replacement Scope

Fixed allocation + Local scope

Fixed allocation + Global scope

Variable allocation + Global scope

Variable allocation + Local scope

The Working Set Strategy

The Working Set Strategy

The Working Set Strategy

The Working Set Strategy

The Page-Fault Frequency Strategy

Load Control

Load Control

Process Suspension