Operating Systems Hadi Salimi Computer Engineering Department Iran - - PDF document
Operating Systems Hadi Salimi Computer Engineering Department Iran University of Science and Technology y gy Tehran, Iran hsalimi@iust.ac.ir Spring 2009 Course motivation and goals Course motivation and goals Programming computer
Hadi Salimi Computer Engineering Department Iran University of Science and Technology y gy Tehran, Iran hsalimi@iust.ac.ir Spring 2009
Programming computer hardware
Operating systems provide a layer Operating systems provide a layer
Understanding operating system
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Introduction and Overview Introduction and Overview Processes and threads Operating system structures Operating system structures Memory management Scheduling Scheduling Input/Output File Systems
y
Security
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Andrew S. Tanenbaum. “Operating Systems design
and implementation”, 3nd ed., Prentice Hall, 2006.
Abraham Silberschatz, Galvin, and Gagne. “Operating Abraham Silberschatz, Galvin, and Gagne. Operating
Systems Concepts”, 7nd ed., John Wiley and Sons, 2005 Willi St lli “O ti S t ” 4 d d
William Stallings. “Operating Systems”, 4nd ed.,
Prentice Hall, 2001.
Andrew S. Tanenbaum. “Modern Operating Systems”,
p g y , 2nd ed., Prentice Hall, 2001.
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What is an operating system? Operating systems history The zoo of modern operating systems Review of computer hardware Operating system concepts System calls Operating system structure
U i t f t th ti t
User interface to the operating system Anatomy of a system call
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IBSYS (IBM 7090)
OS/360 (IBM 360)
MACH OS/360 (IBM 360) TSS/360 (360 mod 67) Michigan Terminal Apollo DOMAIN Unix (System V & BSD) Apple Mac (v 1– v 9)
System
CP/CMS & VM 370 MULTICS (GE 645) Apple Mac (v. 1
MS-DOS Windows NT, 2000, XP
( )
Alto (Xerox PARC) Pilot (Xerox STAR) CP/M Novell Netware Linux FreeBSD CP/M IRIX Solaris FreeBSD PalmOS PocketPC
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MVS VxWorks VxWorks
)
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An Operating System is a program that acts as
an intermediary/interface between a user of a computer and the computer hardware.
It is an extended machine
Hides the messy details which must be performed
Hides the messy details which must be performed Presents user with a virtual machine, easier to use
It is a resource manager
Each program gets time with the resource
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Each program gets space on the resource
The Operating System controls the machine controls the machine
Compiler Debugger
User Application
OS Kernel
Hard
Video Game
Application Operating System ware
Editor
App. Hardware
…
Terminal emulator
Browser
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Static View of System Components
User 1 User 2 User 3 User 4 User n
… Compiler Editor Database Calculator WP Operating System Operating System Hardware
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End User Programmer
Application Programs
Operating- System Designer
O e ti S te Utilities Computer Hardware Operating-System
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First generation: 1945 – 1955
V b Pl b d
Vacuum tubes, Plug boards
Second generation: 1955 – 1965
Transistors, Batch systems
Third generation: 1965 – 1980
Integrated circuits, Multiprogramming
Fourth generation: 1980 – present Fourth generation: 1980 – present
Large scale integration, Personal
computers
Next generation: ???
Next generation: ???
Systems connected by high-speed
networks? Wid t?
13 Wide area resource management?
Run one job at a time
Enter it into the computer (might require rewiring!) Run it
Record the results
Record the results
Problem: lots of wasted computer time!
Computer was idle during first and last steps
Computer was idle during first and last steps
Computers were very expensive!
Goal: make better use of an expensive
commodity: computer time
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Bring cards to 1401 Read cards onto input tape Put input tape on 7094 Perform the computation, writing results to output tape Put output tape on 1401 which prints output
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Put output tape on 1401, which prints output
Structure of a typical 2nd generation job Structure of a typical 2nd generation job
$END
Data for program
$RUN $LOAD
FORTRAN program
$FORTRAN $JOB, 10,6610802, JANE DOE 16
Multiple jobs in memory
P d f
Protected from one
another
Operating system
Job 3 protected from each job as well
Resources (time
Job 1 Job 2 Memory Operating
Resources (time,
hardware) split between jobs Still t i t ti Job 1 partitions Operating system
Still not interactive
User submits job Computer runs it 17 User gets results minutes
(hours, days) later
Job 1 Operat Main C
Task 1 Task 2
Job 2 Job 3 ing System n Memory CPU
Resource utilization Resource utilization
Multiprogramming, multitasking, and multiple users. Time sharing.
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Response time.
Multiprogramming allowed several jobs to be
active at one time
Initially used for batch systems
Cheaper hardware terminals interactive use
Cheaper hardware terminals → interactive use
Computer use got much cheaper and easier
No more “priesthood” No more priesthood Quick turnaround meant quick fixes for problems
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Mainframe operating systems: MVS Server operating systems: FreeBSD, Solaris Multiprocessor operating systems: Cellular IRIX Personal computer operating systems: XP, Linux PDA operating systems: PalmOS, PocketPC Real-time/embedded operating systems: VxWorks,
QNX Smart card operating s stems
Smart card operating systems
⇒Some operating systems can fit into more than one
category
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category
Computer block diagram
Components of a simple personal
CPU internals
Memory Storage pyramid Disk drive structure Anatomy of a device request
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Structure of a large Pentium system
Control Unit Input Unit Output Unit Computer CPU
Monitor Printer
ALU Control Unit
Keyboard Mouse Scanner
Input Unit Output Unit CPU Registers Bank
Modem Modem
Cache Memory
Main Memory ROM RAM
Secondary Memory HD FD CD Flash
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Tertiary Memory Tape
MAR - Memory Address Register
address for next read or write
MBR - Memory Buffer Register
data to be written into memory data to be written into memory receives data read from memory
I/OAR - I/O Address
specifies a particular I/O device
I/OBR - I/O Buffer
exchange of data between an I/O exchange of data between an I/O
module and the processor
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Outside Outside world
Hard drive controller Video controller USB controller Network controller controller controller controller controller CPU
Computer internals (inside the “box”)
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Memory
( )
Execute
Execute unit Fetch unit Decode unit Execute unit Execute unit Holding buffer Fetch unit Decode unit Execute unit Fetch unit Decode unit
(a) A three-stage Pipelined CPU (b) A Superscalar CPU
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Address
0x0002ffff
Address
0x0002ffff
User 2 program and data
0x00027fff 0x0002b000 0x0002ffff Limit
User 2 data User 1 data
Limit2 Base2 0x00029000 0x0002bfff 0x0002ffff 0x0002d000
User 1 program and data
0x0001dfff 0x00023000 0x00027fff Base Limit
User program
Base1 Limit1
2
0x0001dfff 0x00023000 0x00024fff
Operating system
0x0001dfff 0x00000000
Operating system
0x0001dfff 0x00000000
Single base/limit pair: set for each process
T b /li it i t f f d t
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Two base/limit registers: one for program, one for data
Access latency Capacity
y 1 ns 2–5 ns < 1 KB 1 MB Registers Cache (SRAM)
Better
50 ns 5 ms 1 GB 200 GB ( ) Main memory (DRAM) Magnetic disk 50 sec > 1 TB Magnetic tape
Goal: really large memory with very low latency
Better
y g y y y
Latencies are smaller at the top of the hierarchy Capacities are larger at the bottom of the hierarchy
Solution: move data between levels to create illusion of
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large memory with low latency
sector head
Data stored on surfaces
U f
sector platter
Up to two surfaces per
platter
One or more platters per
di k
cylinder platter track
disk
Data in concentric tracks
Tracks broken into sectors
cylinder surfaces
256B-1KB per sector
Cylinder: corresponding
tracks on all surfaces
spindle surfaces
Data read and written by
heads
Actuator moves heads 28
spindle actuator
Heads move in unison
Instruction Interrupt controller CPU 5 Disk controller 3 2 Instructionn Instructionn+1 1: Interrupt 6 1 4 Operating system Interrupt handler 3: Return
Left: sequence as seen by hardware
Request sent to controller, then to disk
Disk responds signals disk controller which tells interrupt
p 2: Process interrupt
Disk responds, signals disk controller which tells interrupt
controller
Interrupt controller notifies CPU
Ri ht i t t h dli ( ft i t f i )
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Right: interrupt handling (software point of view)
Process Management Memory Management File Management I/O Management Process Scheduler Inter Process Communication Network Unit
C d I t t
Command Interpreter Security Management
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program can use
program counter & stack pointer)
A
pointer)
processes in a process table
B C D
processes
relationships
E F G
processes: B, C, and D
E d F
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processes: E and F
G
Processes have three
t
0x7f f f f f f f
segments
Text: program code Data: program data
Stack 0x7f f f f f f f
Statically declared
variables
Areas allocated by
malloc() or new (heap) malloc() or new (heap)
Stack
Automatic variables Procedure call information
Data Data
Address space growth
Text: doesn’t grow Data: grows “up”
Text
32 Data: grows up Stack: grows “down”
0x00000000
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(a) A Potential deadlock (b) An Actual deadlock
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File system for a university department
Before mounting,
files on floppy are inaccessible
After mounting floppy on b,
files on floppy are part of file hierarchy
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files on floppy are part of file hierarchy
Processes may want to exchange information with each
th
Many ways to do this, including
Network Pipe (special file): A writes into pipe, and B reads from it
Process Process
A B
Pipe
Two processes connected by a pipe
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Two processes connected by a pipe
Monolithic system Layered system Virtual machine Exokernel Client/Server
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Main Main procedure Service Procedures Utility Procedures
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Simple structuring model for a monolithic system
Applicatio ns ns
User space Kernel space
System call interface
Kernel space MM = Memory Manager PS P S h d l MM PS IPC FS Kernel PS = Processor Scheduler IPC = Inter Process Communication MM PS IPC FS I/O Net
…
FS = File System I/O = Input/Output manager Net = Network manager
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Net = Network manager
User
Layer 5
User Application
User space
Layer 4
Message Interpreter
Har
I/O Management
Kernel space
Layer 3 Layer 2
P S h d li Memory Management
rdware
Layer 1
Structure of the THE operating system
Process Scheduling
Layer 0
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Structure of the THE operating system
App1 App2 App3 VM/370 CMS (VMW) Linux pp1 pp2 pp3 CMS (VMW) CMS (VMW) Windows NT FreeBSD I/O instructions System calls Calls to simulate I/O Bare hardware VM/370 Calls to simulate I/O “Real” I/O instructions
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Same as Virtual machine Assign one virtual computer to any user Allocate sub set of resource to any virtual
machine
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Cli t P T i l Cli t Fil M
Microkernel Client process Process server Terminal server Client process File server Memory server
…
User mode Kernel mode e e
Client obtains service by sending messages to server The client-server model
Processes (clients and OS servers) don’t share memory
C i ti i i
sending messages to server processes
Communication via message-passing Separation reduces risk of “byzantine” failures
Examples include Mach, QNX, early versions of Windows
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NT
Applicatio ns ns System call interface
User space Process Scheduler File System Device manager
…
Micro Kernel Kernel space IPC Memory Management Synchronization
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Memory Management Synchronization
The client-server model in a distributed The client server model in a distributed system
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Programs want the OS to perform a service
Access a file Create a process
Others
Others…
Accomplished by system call
Program passes relevant information to OS
Program passes relevant information to OS
OS performs the service if
The OS is able to do so The service is permitted for this program at this time The service is permitted for this program at this time
OS checks information passed to make sure it’s OK
Don’t want programs reading data into other programs’
!
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memory!
Applications Applications Applications
User space K l
Applications Applications Applications System call interface
Kernel space MM PS IPC FS MM PS IPC FS I/O Net
…
OS Component
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System call:
d(fd b ff l th)
0xffffffff Library
read(fd,buffer,length)
Program pushes
arguments, calls library
Return to caller Trap to kernel (read call)
Library sets up trap, calls
OS
OS handles system call
Trap to kernel Trap code in register User space 2 3 8
OS handles system call Control returns to library Library returns to user
Increment SP Call read Push arguments 1 4 7 9
program
There are 9 steps in
making the system call
Push arguments Dispatch Sys call Kernel space 1 5 6 User code
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making the system call
Dispatch y handler space (OS) 0
Call Description
fd = open(name how) Open a file for reading and/or writing fd = open(name,how) Open a file for reading and/or writing s = close(fd) Close an open file n = read(fd,buffer,size) Read data from a file into a buffer n = write(fd,buffer,size) Write data from a buffer into a file s = lseek(fd,offset,whence) Move the “current” pointer for a file s = stat(name,&buffer) Get a file’s status information (in buffer) ( , ) ( ) MINIX System calls
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Call Description
pid = fork() Create a child process identical to the parent parent pid=waitpid(pid,&statloc,options) Wait for a child to terminate s = execve(name,argv,environp) Replace a process’ core image exit(status) Terminate process execution and return status s = chdir(dirname) Change the working directory s = chmod(name,mode) Change a file’s protection bits s = kill(pid,signal) Send a signal to a process seconds = time(&seconds) Get the elapsed time since 1 Jan 1970 MINIX S t ll
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( ) p MINIX System calls
while (TRUE) { /* repeat forever */ while (TRUE) { / repeat forever / type_prompt( ) ; /* display prompt */ read_command (command, parameters); /* input from terminal */ if (fork() != 0) { /* fork off child process */ /* Parent code */ waitpid( -1, &status, 0); /* wait for child to exit */ } else { /* Child code */ execve (command, parameters, 0); /* execute command */ } }
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Some UNIX and Win32 API calls
How does a batch operating system differ from
lti d ti t ? a multiprogrammed operating system?
Why is multiprogramming useful? Why are multiprogrammed systems much more Why are multiprogrammed systems much more
difficult to implement than are batch systems?
What is timesharing? How does it differ from
g multiprogramming?
What is an online system?
What is a real time s stem?
What is a real-time system? Which systems try to maximize throughput?
Which ones try to minimize response time?
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Which ones try to minimize response time?
What type of operating system would you use What type of operating system would you use
For editing a letter? For controlling a chemical reaction? For processing payroll? In a cellphone? In a toy? For surfing the web? For air traffic control?
F i tifi i l ti ?
For a scientific simulation? To play MP3?
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What connects the processor to memory? What are the components of the storage
hierarchy?
What is between the processor and I/O
devices? What are the components of a disk?
What are the components of a disk? What is an interrupt?
Why are interrupts useful?
Why are interrupts useful? What happens to program execution when an
interrupt occurs?
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interrupt occurs?
Does it differ if the operating system is
monolithic or a microkernel?
What are the steps involved when the operating
t i lithi ? system is monolithic?
What additional steps happen in case of a
microkernel? microkernel?
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