Transcript CSCI 3753 Operating Systems Spring 2005

CSCI 3753 Operating Systems
Spring 2005
Professor Rick Han
Department of Computer Science
University of Colorado at Boulder
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
What is an Operating System?
• Windows, Linux
• What is an
application?
Applications
– Powerpoint, Realplayer
• What is hardware?
• An operating system is
a layer of software
between applications
and hardware
Operating System
Hardware
What is an Operating System?
• An operating system is a
layer of software
between many
applications and diverse
hardware that
– helps to better manage
the hardware for an
application
App2
App1
App3
Operating System
• otherwise an application
saving a file to disk
would have to know how
the disk operates
Disk Memory CPU Display Mouse I/O
– helps to share resources
and isolate access to
resources between
multiple applications
What is an Operating System?
• A PC operating
system consists
of multiple
components
– scheduler
– virtual memory
system
– file system
– other...
App2
App1
File
System
App3
VM
Scheduler
OS
“Kernel”
Disk Memory CPU Display Mouse I/O
What is an Operating System?
OS?
App2
App1
Posix, Win32,
Java, C library API
System call API
– 160 in Linux
App3
System Libraries and Tools
(Compilers, Shells, GUIs)
File
System
VM
Scheduler
OS
“Kernel”
Device driver “API”
Note: different OS kernels can
support the same system call API
Disk
Memory CPU
Display Mouse I/O
What is an Operating System?
App1 App2 App3
App1 App2 App3
Networking
Stack
OS
HW
OS
Networking
HW
HW
Networking
Stack
Networking
HW
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
• Distributed
Operating
Systems
– Networked
File System
– OS adds
TCP/IP
Network
Stack
– Device driver
support for
Networking
cards
Operating System Trends
• Hardware has evolved quickly - OS must adjust
– Moore’s Law applies to CPU speed and/or memory
size: doubles every 18 months => exponential!
– But Moore’s Law doesn’t apply to disk access speed
or to battery life
– Diverse devices with high bandwidth requirements
??
Storage Evolution:
Punch card
stores code
1950s-80s
Tape Drive
1950s-80s
Disk Drive
1960s-2000s
Flash Drive
already at 1 GB @ $60
=> OS disk scheduling
obsolete??
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
• Today’s 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!
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
Operating Systems: Key Concepts
• Multiprogramming
– when CPU idle (e.g. blocked on I/O), run
another program => improved CPU
utilization
1. batch mode - running jobs or programs
sequentially, one after the other
2. Time sharing and concurrency - finely
interleaved sharing of CPU
• useful to give impression of interactivity!
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
Operating Systems Research
• Papers are published at premier OS
conferences like:
– ACM SOSP 2005 (Symposium on Operating
Systems Principles) - http://www.sosp20.com/
– USENIX OSDI 2004 (Operating System
Design and Implementation) http://www.usenix.org/events/osdi04/
• Secure Operating Systems
• Wireless Sensor Networks
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
Interne
t
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
Military Applications of Sensor
Nets
• Battlefield monitoring
Basestation
• Sound, heat, metal,
vibration
• Deployed in Vietnam,
Afghanistan, Iraq Wireless sensor network
• REMBASS II, UGS, …
• 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