Linux Internals

Table of Contents

1. Introduction and History

Course Objectives

Introducing the other influence in this course

History

1955

1966

1969 to 1970

Assembler/ compilers / hardware architecture

1971 - 1973

1973 - 1974

1974 - 1975

1976 - 1978

1979

1980

1977 to 1983

1989

1992 to 1998

This is the story of Linux

An Introduction to Linux

The story of BSD

1994 1.0 release

The Operations of a Unix/Linux System

In Libraries Level

Kernel

Memory

2. Booting

What the kernel does when it starts up

Booting

Switch On

3. Logging in

Reading the Man pages - A review

init

RUNLEVELS

BOOTING

CHANGING RUNLEVELS

TELINIT(Older technology look at "init q")

BOOTFLAGS

INTERFACE

SIGNALS

Run Level versus programs

Default run level to go to as defined in /etc/inittab

Example Debian /etc/rcS.d/ directory

Getty and gettdefs

Terminal Emulation

Terminfo (Some Extracts from stated reference material)

Terminfo Compiler (tic)

Save disk space

TERM

Multiple Virtual Terminals

Some tips

In Summary

4. The Kernel versus Process Management

The Kernel

Overview of kernel/process control, resources

Executing a process

Process Management

Shell Command line parsing

Command Execution and Process Creation

Process Properties

Process Life Cycle

The state of a process

Scheduler

Linux Multitasking

Task States

Time-slicing

Timer

Task switching

When does switching occur?

5. Memory Management

The Buffer Cache

The Directory Cache

Paging and swapping

Introduction

Swap Space

Swapping

Paging

The working sets

Implementation of swapping and paging in different systems

Virtual memory

6. Drivers

Introduction to drivers

Driver Types

Driver Implementations

Driver Management

Listing currently loaded modules

Loading Modules

Unloading modules

Other module management commands

Device Drivers

7. System Tuning

Performance Tuning

A machine is a finite resource

System Model - Sleep Queue

Scheduling, Priority Calculation and the nice value.

The algorithm

Scheduling code - From the process table perspective

More detail on scheduling

Performance Criteria

Limiting the memory usage

Times

Top (Some extracts are from the man pages)

Sar (Some extracts are from the man pages)

Vmstat (Some extracts are from the man pages)

Iostat (Some extracts are from the man pages)

ps (Some extracts are from the man pages)

8. Tips and Tricks

Why recompile the kernel at all?

To prepare

Using "config"

Creating dependencies and re-compiling the kernel

Edit LILO config file

General Information on hard disk partitions

Generic Unix filesystem properties

Generic Unix filesystem enhancements

Free Blocks bitmap

Block Groups

Extents

Datablock pre-allocation

Filesystems

Why use filesystems?

Filesystem support inside the kernel

A logical division

Attaching a filesystem (mount)

Filesystems other than Linux filesystems and some utilities

A filesystem Structure

The Virtual Filesystem

The Ext2 and Ext3 Filesystems

File System Checking

Performing a filesystem check

Lost+found directory

The proc filesystem

Exercise:

The System Logger - syslogd

How does syslogd work

Why use a log file to record happenings on systems?

Let's look at the .conf file

Setting up the loghost

Inter-Process Communication

Signals

A. Referances

Simone Demblon reference material

Online sources for recommended reading

Index