1. Lecture 2: Introduction to Operating Systems
Joe McCarthy
CSS 430: Operating Systems - Introduction

2. CSS 430: Operating Systems - Introduction
Outline
Questions from last time?
Updates
Introduction to Operating Systems (Ch 1)
Overview & History
Process management
Memory Management
File System Management
Informal Linux Lab orientation (UW1-320)
CSS 430: Operating Systems - Introduction

3. CSS 430: Operating Systems - Introduction
Updates
Updated syllabus page (
Shared Discussion Board (Sections A & B)
Slides posted from last time (“Overview” link)
Will merge/create class homepage by Monday
Shifted MW evening office hours:
Old: 5:00-5:30pm, UW2-317
New: 7:45-8:15pm, UW1-220 (and/or UW2-317)
Best to ahead of time
Chapter 2, Assignment 1: next time
“Program 1” via “Homework Assignments” on main CSS 430 page
CSS 430: Operating Systems - Introduction

4. Chapter 1: Introduction
What Operating Systems Do
Computer-System Organization
Computer-System Architecture
Operating-System Structure
Operating-System Operations
Process Management
Memory Management
Storage Management
Protection and Security
Distributed Systems
Special-Purpose Systems
Computing Environments
Open-Source Operating Systems
Material derived, in part, from Operating Systems Concepts with Java, 8th Ed. © 2009 Silberschatz, Galvin & Gagne
CSS 430: Operating Systems - Introduction

5. What is a computer system?
CSS 430: Operating Systems - Introduction

6. What is a computer system?
CSS 430: Operating Systems - Introduction

7. What is an Operating System?
CSS 430: Operating Systems - Introduction

8. What is an Operating System?
OS is a resource allocator
Manages resources efficiently & efficiency, resolves conflicts
OS is a control program
Controls execution of programs, operations of devices
No universally accepted definition
“Everything a vendor ships when you order an operating system”
CSS 430: Operating Systems - Introduction

9. What is an Operating System?
OS is a resource allocator
Manages resources efficiently & efficiency, resolves conflicts
OS is a control program
Controls execution of programs, operations of devices
No universally accepted definition
“Everything a vendor ships when you order an operating system”
Kernel vs. system program vs. application program?
CSS 430: Operating Systems - Introduction

10. What is an Operating System?
OS is a resource allocator
Manages resources efficiently & efficiency, resolves conflicts
OS is a control program
Controls execution of programs, operations of devices
No universally accepted definition
“Everything a vendor ships when you order an operating system”
Kernel: “The one program running at all times on the computer”
Everything else is either a system program (ships with the OS) or an application program
CSS 430: Operating Systems - Introduction

11. What is an Operating System?
OS is a resource allocator
Manages resources efficiently & efficiency, resolves conflicts
OS is a control program
Controls execution of programs, operations of devices
No universally accepted definition
“Everything a vendor ships when you order an operating system”
Kernel: “The one program running at all times on the computer”
Everything else is either a system program (ships with the OS) or an application program
Bootstrap program?
CSS 430: Operating Systems - Introduction

12. What is an Operating System?
OS is a resource allocator
Manages resources efficiently & efficiency, resolves conflicts
OS is a control program
Controls execution of programs, operations of devices
No universally accepted definition
“Everything a vendor ships when you order an operating system”
Kernel: “The one program running at all times on the computer”
Everything else is either a system program (ships with the OS) or an application program
Bootstrap program is loaded at power-up or reboot
Typically stored in firmware (ROM or EEPROM)
Initializes all aspects of system, loads OS kernel and starts execution
CSS 430: Operating Systems - Introduction

13. What is an Operating System?
OS is a resource allocator
Manages resources efficiently & efficiency, resolves conflicts
OS is a control program
Controls execution of programs, operations of devices
No universally accepted definition
“Everything a vendor ships when you order an operating system”
Kernel: “The one program running at all times on the computer”
Everything else is either a system program (ships with the OS) or an application program
Bootstrap program is loaded at power-up or reboot
Typically stored in firmware (ROM or EEPROM)
Initializes all aspects of system, loads OS kernel and starts execution
OS desiderata?
CSS 430: Operating Systems - Introduction

14. What is an Operating System?
OS is a resource allocator
Manages resources efficiently & efficiency, resolves conflicts
OS is a control program
Controls execution of programs, operations of devices
No universally accepted definition
“Everything a vendor ships when you order an operating system”
Kernel: “The one program running at all times on the computer”
Everything else is either a system program (ships with the OS) or an application program
Bootstrap program is loaded at power-up or reboot
Typically stored in firmware (ROM or EEPROM)
Initializes all aspects of system, loads OS kernel and starts execution
OS desiderata: effective, efficient, easy-to-use
CSS 430: Operating Systems - Introduction

15. Computer System Components
CSS 430: Operating Systems - Introduction

16. CSS 430: Operating Systems - Introduction
Computer Hardware
CSS 430: Operating Systems - Introduction

17. Computer system operation
CPU & I/O devices can execute concurrently
Each device controller
is in charge of a particular device type
has a local buffer
CPU moves data from/to main memory to/from local buffers
Device I/O is from the device to local buffer of controller
Device controller informs CPU that it has finished its operation by causing an interrupt
CSS 430: Operating Systems - Introduction

18. Interrupt handling: motivation
“…on a fully saturated 100 Mb/s Ethernet link with an average packet size of 512 bytes, the network adapter may generate over 20,000 interrupts per second.
If each interrupt takes 15μsec, over 30% of the processor time may be devoted to interrupt handling.”
Profiling Interrupt Handler Performance through Kernel Instrumentation
Branden Moore, Thomas Slabach, Lambert Schaelicke
Proceedings of the 21 st IEEE International Conference on Computer Design, 2003
CSS 430: Operating Systems - Introduction

19. CSS 430: Operating Systems - Introduction
Interrupt handling
CSS 430: Operating Systems - Introduction

20. CSS 430: Operating Systems - Introduction
Interrupt handling
CSS 430: Operating Systems - Introduction

21. Brief history of Operating Systems
Batch systems
Multiprogramming
Time-sharing
Multiprocessing
Multi-computer systems
CSS 430: Operating Systems - Introduction

22. CSS 430: Operating Systems - Introduction
Batch Systems
Job: program + the data + control info
Programmers pass their jobs to an operator
The operator batches together jobs
OS transfers control from one job to another
Job output is sent back to the programmer
IBM 1402
IBM 1403
CSS 430: Operating Systems - Introduction

23. CSS 430: Operating Systems - Introduction
Multiprogramming
Several jobs are kept in main memory a same time
OS picks one of them to execute
The job may have to wait for a slow I/O operation to complete
OS picks & executes another job
OS Requirements:
Job scheduling
Memory management
IBM System/360
CSS 430: Operating Systems - Introduction

24. CSS 430: Operating Systems - Introduction
Timesharing
Timesharing (multitasking): CPU switches jobs frequently so that multiple users can interact with their jobs while they is running (interactive computing)
Response time should be < 1 second
Each user has at least one program executing in memory process
If several jobs ready to run at the same time  CPU scheduling
If processes don’t fit in memory, swapping moves them in and out to run
Virtual memory allows execution of processes not completely in memory
CSS 430: Operating Systems - Introduction

25. Multiprocessing Multiple CPUs, shared memory (asymmetric or symmetric)
CSS 430: Operating Systems - Introduction

26. Multiprocessing Multiple CPUs, shared memory (asymmetric or symmetric)
Advantage(s)?
CSS 430: Operating Systems - Introduction

27. Multiprocessing Multiple CPUs, shared memory (asymmetric or symmetric)
Advantage(s)?
Increased throughput
Economy of scale
Increased reliability
CSS 430: Operating Systems - Introduction

28. Multi-processor vs. Multi-core
CSS 430: Operating Systems - Introduction

29. Multi-processor vs. Multi-core
Multiple CPUs on separate chips
Multiple CPUs on same chip
CSS 430: Operating Systems - Introduction

30. Multi-processor vs. Multi-core
Multiple CPUs on separate chips
Multiple CPUs on same chip
Advantage(s)?
CSS 430: Operating Systems - Introduction

31. Multi-processor vs. Multi-core
Multiple CPUs on separate chips
Multiple CPUs on same chip
Advantage(s)?
More efficient
Faster
Less power
Less heat
CSS 430: Operating Systems - Introduction

32. Multi-computer Systems
Local Area Network (LAN) (shared storage or other peripherals)
Client-Server System (e.g., WWW)
CSS 430: Operating Systems - Introduction

33. CSS 430: Operating Systems - Introduction
How a Computer Works
CSS 430: Operating Systems - Introduction

34. Instruction Execution Cycle
CSS 430: Operating Systems - Introduction

35. Two modes of processing
Why 2 modes?
What causes shifts between modes?
Why would a CPU need a timer?
CSS 430: Operating Systems - Introduction

36. CSS 430: Operating Systems - Introduction
Process Management
Activities an OS must perform?
CSS 430: Operating Systems - Introduction

37. CSS 430: Operating Systems - Introduction
Process Management
Activities an OS must perform:
Creating and deleting user & system processes
Suspending and resuming processes
Providing mechanisms for process synchronization
Providing mechanisms for process communication
Providing mechanisms for deadlock handling
CSS 430: Operating Systems - Introduction

38. CSS 430: Operating Systems - Introduction
Hierarchy of Memory
Variables:
CSS 430: Operating Systems - Introduction

39. CSS 430: Operating Systems - Introduction
Hierarchy of Memory
Variables:
Speed
Cost
Size
Volatility
CSS 430: Operating Systems - Introduction

40. CSS 430: Operating Systems - Introduction
Memory Performance
CSS 430: Operating Systems - Introduction

41. CSS 430: Operating Systems - Introduction

42. CSS 430: Operating Systems - Introduction

43. CSS 430: Operating Systems - Introduction
Memory Management
Activities OS must perform?
CSS 430: Operating Systems - Introduction

44. CSS 430: Operating Systems - Introduction
Memory Management
Activities OS must perform:
Keeping track of which parts of memory are currently being used and by whom
Deciding which processes (or parts thereof) and data to move into and out of memory
Allocating and deallocating memory space as needed
CSS 430: Operating Systems - Introduction

45. File System Management
Activities an OS must perform?
CSS 430: Operating Systems - Introduction

46. File System Management
Activities an OS must perform:
Creating and deleting files & directories
Primitives to manipulate files & directories
Mapping files onto secondary storage
Backup files onto stable (non-volatile) storage media
CSS 430: Operating Systems - Introduction

47. Speaking of file systems …
CSS 430: Operating Systems - Introduction

48. CSS 430: Operating Systems - Introduction
See your UW NetID in that list?
CSS 430: Operating Systems - Introduction

49. CSS 430: Operating Systems - Introduction
Linux overview
Basic commands
Directories: cd, mkdir, ls
Manipulate files: cp, mv
Edit files: vi, pico, emacs
Help: man
Print: lpr -Puw1-320-p1
Compile: g++, javac
Remote login:
More info:
CSS 430: Operating Systems - Introduction

50. CSS 430: Operating Systems - Introduction
For next time
Readings
Chapter 2: Operating System Structures
Assignment 1
CSS 430: Operating Systems - Introduction