Transcript Slides for week 1 - Computing Science

CMPT 300 Day: Operating System
Instructor: Senqiang Zhou
TA: Rong Ge
{szhoua, rge}@cs.sfu.ca
What Is This Course About?
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Office Hours & Places
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Instructor:
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Time: Tue. 10:00-12:00
Fri. 14:00-15:00
Place: MTF109 North - CSIL Linux Study Area
E-MAIL List: [email protected]
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Wed 11:00-12:00
TA:
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Time: Mon. 14:30-15:30
Place: ASB 9911
ACS SFU account desk at Strand Hall
Course web-page:
 http://www.cs.sfu.ca/CC/300/szhoua/
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Grading
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Four assignments count for 20%.
One term project counts for 15%.
One 1-hour mid-term exam counts for
20%.
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Covers Ch 1 to Ch 3 .
One 3-hour final exam counts for 45%.
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Covers Ch1 to Ch 6.
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Pre-requisites
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C/C++:
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Basic hardware knowledge:
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Necessary for term project
Necessary to understand the codes in
textbook
CPU, memory, bus, hard disk, I/O devices
Basic data structures:
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Queue, stack, etc.
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Chapter 1
Introduction
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Outline
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Definitions of operating system
History of operating systems
Categories of operating systems
Computer hardware review
Operating system concepts
System calls
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Why Do We Need OS?
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Many resources
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Many tasks
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Hardware: processors, memory, disks, printers,
keyboard, monitors, network interfaces, …
Software: compilers, office tools, browsers,
games, …
Programming, surfing web, handling emails,
solving equations, playing music, …
Many users
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Share the resources: fairness Vs. Efficiency
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A Computer Without OS
Consider a daily task: read data from
diskette
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Basic commands: 13 parameters
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Controller chips
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Disk address, #blocks to read, #blocks per
track….
23 status and error field
Do you want to program the hardware
directly?
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A simpler interface is needed!
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The Benefits of OS
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Hide the tedious details
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Provide a variety of services: system calls
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They are out of the user’s interest
E.g., to access data, only need to specify the file
name.
A set of procedures
an be called by programs using special
instructions.
A simple interface
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Present key features to programmer
Meet requirements from many programs
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OS As A Virtual Machine
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Virtual machine/extended machine
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Hide the underlying hardware
Access hardware through a set of system
calls
Trade-off
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Higher efficiency in program development
and system management
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More important with complex software
Less efficiency in program execution
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Less important with faster machine
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OS As A Resource Manager
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Multiplexing (sharing) resources
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In time
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In space
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Users/programs get parts of resources
Main memory, disk, etc.
Protecting resources
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Users/programs take turns using resources
CPU, printers, etc.
E.g., user’s memory space
Issues about a good manager
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Fairness, efficiency, safety, …
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What Is An Operating System?
Provide
user
programs
with a
simpler
interface
Banking
system
Airline
reservation
Web browser
Compilers
Editors
Command
interpreter
Operating system
User
programs
System
programs
Machine language
Micro-architecture
Hardware
Physical devices
Manage
resources
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Outline
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What is an operating system?
History of operating systems
Categories of operating systems
Computer hardware review
Operating system concepts
System calls
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History of Operating Systems
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OS and architecture of computers
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Computer evolves  so does OS
To provide better service  OS has impact
on computer design
Keep evolving through years (1944-)
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Four generations so far during 60 years
Speed, volume, storage, interface…
Most important: price keeps dropping
How many generations for car industry?
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The First Generation Computer
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Vacuum tubes and plug-boards
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Applications:
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Straightforward numerical calculations
Absolutely no game!
Scenario
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1944-1955
Huge volumes, slow speed, low stability, expensive!
Single group of people designed, built, programmed,
operated and maintained a machine
All in absolute machine language: no assembly language
No operating system
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People did all the tasks.
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The Second Generation OS
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Transistors and batch systems
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1955-1965
Applications
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Scientific and engineering calculation
Programming Language: FORTRAN
IBM 1401
IBM 7094
Read batch
of jobs onto
tape
Cards from
programmers
Input tape
Do computing
IBM 1401
Print out
Output
tape
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Ancestor of Today’s OS
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Batch system
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Load next job
A typical input job: series of commands
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Read a job from tape  run the job 
write output onto a output tape
$JOB$FORTRAN$LOAD$RUN
Examples:
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FMS, IBSYS
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The Third Generation OS
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Features: ICs and multiprogramming
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1965-1980
Applications
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Numerical calculations in science &
engineering
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Word-oriented, large-scale scientific computers
Massive commercial data processing
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Character-oriented, commercial computers
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Key Advances in 3rd Gen OS
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Multiprogramming
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Spooling
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Run job 2 while
job 1 waiting for I/O
Keep CPU busy
Job 3
Job 2
Job 1
OS
Memory
partitions
Read jobs from cards to disk asap
Load new jobs from disk whenever old job done
Time sharing
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CPU is allocated in turn
Different from multiprogramming
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Milestones
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IBM OS/360
M.I.T. CTSS
M.I.T. MULTICS
Ken Thompson UNIX
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AT&T UNIX System V
UC Berkeley UNIX BSD
IEEE POSIX
Andrew S. Tanenbaum MINIX
Linus Torvalds Linux
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The Fourth Generation OS
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Personal computers
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1980-now
VLSI circuits
Cheap: an individual has her own computer
Milestones
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Kildall CP/M for Intel 8080, Z80
MS-DOS/BASIC for IBM PC
Engelbart GUI
MS Windows, Windows NT
UNIX X Windows
Network & distributed operating systems
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Outline
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What is an operating system?
History of operating systems
Categories of operating systems
Computer hardware review
Operating system concepts
System calls
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Categories of OS
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Mainframe operating systems
Server operating systems
Multiprocessor operating systems
Personal computer operating systems
Real-time operating systems
Embedded operating systems
Smart card operating systems
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Mainframe Operating Systems
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Characters of mainframe computers
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Features of OS
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Strong I/O capability, e.g., 1000 disks, TB
space
High-end servers: web server, B2B server
Batch (background)
Transaction processing (interactive)
Timesharing
Example: IBM OS/390
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Server Operating Systems
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Hardware platforms
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Services
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Very large personal computers or
workstations
Printing
File accessing
Web
Examples
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UNIX, Windows 2000, Linux
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Multiprocessor Operating Systems
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Multiple CPUs within a single system
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Parallel computers:
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Multi-computers:
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Local memory, connected via LAN, tightly coupled
Multiprocessors:
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Local memory, connected via WAN, loosely coupled
share memory, connected via BUS
Features of OS
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Variations of the server operating systems
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Special features for communication and connectivity
between CPUs
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Personal Computer OS
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User friendly interface
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Easy to manipulate
Abundant application software: word
processing, spreadsheets, internet access,
game…
Examples
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Windows 98, Windows 2000
Macintosh operating system
Linux
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Outline
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What is an operating system?
History of operating systems
Categories of operating systems
Computer hardware review
Operating system concepts
System calls
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Components of A Computer
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CPU
System bus: connect all components
Memory
Monitor
Keyboard
Video
controller
Keyboard
controller
Floppy
disk
driver
Hard
disk
driver
Floppy
disk
controller
Hard disk
controller
Bus
I/O Devices
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CPU (Processor)
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Basic model
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Fetching instruction  decoding  executing
Different CPUs have different instruction sets.
Registers
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Program counter: pointer to next instruction
PSW: program status word
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Condition code bit, the mode (kernel or user), etc.
Stack pointer: point to the top of current stack
General registers: hold temporary results
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Working Modes
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Two modes in CPU
Kernel mode: full capability
 User mode: I/O, memory protection
instructions are disallowed.
System calls: get OS service for user
program, switch to kernel mode by TRAP
instruction.
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User Program
System Call
User mode
User Program
OS
Service Done
Kernel mode
User mode
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Memory Hierarchy
Reason: Trade off between speed and Cost
Typical access
time
Typical capacity
1 nsec
Register
<1 KB
2 nsec
Cache
1 MB
10 nsec
Main memory
10 msec
Magnetic disk
5-100 GB
100 sec
Magnetic tape
20-100 GB
RAM
64MB-1G
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Memory Management
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Hold multiple programs in main memory
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Improve CPU utilization. Why?
Problems
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Protection
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Program A is not allowed to fetch data within program B
Protect kernel from users’ programs
Relocation
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Each program starts from logical address 0
How to load and allocate them into main memory?
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Base/Limit Registers
0xFFFFFFF
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Base register
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Record the size of program + data
Limit of addresses
Limit
User
program
and data
Virtual address  physical address
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User
program
and data
Limit register
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Point to the start of a program
Its content is added to every program
address
Base
Base = 4096, limit = 6114
Virtual addr = 2000  physical addr
= 2000+4096=6096 < limit, legal!
MMU: memory management unit
Operating
system
0
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Split Program and Data
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Why: multiple users
may run a same
program
Registers
when
running
program 1
How: base/limit
Limit-2
registers for program
Base-2
and data, respectively
Limit-1
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Overhead of switching:
Base-1
context switch
Registers
when
running
program 2
Limit-2
User-2
data
Base-2
User-1
data
User
program
Limit-1
Base-1
Operating
system
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