CSCI 3753 Operating Systems Spring 2005

1
CSCI 3753 Operating SystemsSpring 2005

• Professor Rick Han
• Department of Computer Science
• University of Colorado at Boulder

2
CSCI 3753 Announcements

• Who am I?
• Review of syllabus
• TA introduces first programming shell assignment
  (similar to lab exercise 2.1) and CSEL logistics
• Introduction to Operating Systems
• Read chapters 1 and 2 in the textbook

3
What is an Operating System?

• Windows, Linux
• What is an application?
• Powerpoint, Realplayer
• What is hardware?
• An operating system is a layer of software
  between applications and hardware

Applications
Operating System
Hardware
4
What is an Operating System?
App2

• An operating system is a layer of software
  between many applications and diverse hardware
  that
• helps to better manage the hardware for an
  application
• otherwise an application saving a file to disk
  would have to know how the disk operates
• helps to share resources and isolate access to
  resources between multiple applications

App3
App1
Operating System
Disk
Memory
CPU
Display
Mouse
I/O
5
What is an Operating System?
App2

• A PC operating system consists of multiple
  components
• scheduler
• virtual memory system
• file system
• other...

App3
App1

OS Kernel
Disk
Memory
CPU
Display
Mouse
I/O
6
What is an Operating System?
App2
App3
App1
System Libraries and Tools (Compilers, Shells,
GUIs)

OS Kernel
Memory
CPU
Disk
Display
Mouse
I/O
Note different OS kernels can support the same
system call API
7
What is an Operating System?

• Distributed Operating Systems
• Networked File System
• OS adds TCP/IP Network Stack
• Device driver support for Networking cards

Network
e.g. Internet, or Ethernet, or WiFi

• Examples
• App1 is a distributed client server app, e.g.
  App1 on left is Web browser, App1 on right is Web
  server

8
Operating System Trends

• Hardware has evolved quickly - OS must adjust
• Moores Law applies to CPU speed and/or memory
  size doubles every 18 months gt exponential!
• But Moores Law doesnt apply to disk access
  speed or to battery life
• Diverse devices with high bandwidth requirements

9
Operating System Trends

• Hardware support for operating systems has
  evolved too
• Mode bit support in CPU
• user mode vs. kernel/supervisor mode
• early PCs did not have this support
• Todays embedded microcontrollers also lack this
  support
• Page faulting hardware and MMU
• Lack of such HW support can allow user programs
  to accidentally or maliciously overwrite OS
  kernel code!

10
Operating System Trends

• Proliferation of OSs on large scale and small
  scale and across features
• Multi-processor OSs - scaling up
• Cell phone OSs - scaling down
• Real-Time OS for Embedded and Multimedia Systems

11
Operating Systems Key Concepts

• Multiprogramming
• when CPU idle (e.g. blocked on I/O), run another
  program gt improved CPU utilization
• batch mode - running jobs or programs
  sequentially, one after the other
• Time sharing and concurrency - finely interleaved
  sharing of CPU
• useful to give impression of interactivity!

12
Operating Systems Key Concepts

• Time-sharing examples
• multiple processes sharing time locally on a CPU
• multiple user terminals remotely sharing
  processing time with a central server
• keystroke delay

13
Operating Systems Research

• Papers are published at premier OS conferences
  like
• ACM SOSP 2005 (Symposium on Operating Systems
  Principles) - http//www.sosp-20.com/
• USENIX OSDI 2004 (Operating System Design and
  Implementation) - http//www.usenix.org/events/osd
  i04/
• Secure Operating Systems
• Wireless Sensor Networks

14
Wireless Sensor Networks

• Groups of sensor nodes connected by a wireless
  networking fabric

• Sensor nodes consist of CPU/memory, radio,
  sensors, and power units
• Monitor environment

• Self-configure into wireless multi-hop network

15
Applications of Wireless Sensor Networks

• Nature
• Wildlife Great Duck Island (Berkeley 2002)

• Habitat San Jacinto Nature Preserve (UCLA)
• Monitor atmosphere (NCAR)

• Home
• Security (commercial)
• Medical - Assistive Technology (BP Visualization
  Center, L3D, Ga Tech)
• Mobile/Robotic WSANs

16
Military Applications of Sensor Nets

• Battlefield monitoring
• Sound, heat, metal, vibration
• Deployed in Vietnam, Afghanistan, Iraq
• REMBASS II, UGS,

Basestation
Wireless sensor network
17

• MANTIS Research Project at University of Colorado
  at Boulder, Dept Computer Science
• Professor Rick Han
• 10 undergraduate and graduate students
• http//mantis.cs.colorado.edu
• Designed the MANTIS OS for micro sensor nodes -
  multithreaded, in C
• Designed the ELF flash file system for micro
  sensor nodes