Transcript 1.1. OS Introduction Operating System typesx

Where are being used the OS?
Windows
Mac OS
Linux
• Widespread
• Invisible
OS
Routers,
switches, …
OS
Basic OS
Android OS
OS
OS
OS
Internet of
Things
Raspbian OS
OS
Operating Systems Introduction
This course structure
OS Introduction
Processes, Threads,
Scheduling, Synchronization
Memory management
I/O systems
Interrupts
File Systems
Operating
Systems
Protection and Security
Distributed Processing
Networks
Different OS comparison
Sources:
• Yale university
• UC Berkeley
• JHU
• My experience
Assignments, Project
Exercises, Assignments, Project (C, C++)
WinAPI
Windows OS
Real
Workstation
Linux API
Linux OS
Virtual
Machine
Student’s should complete programming assignments on “Unix and Windows Processes
&Threads programming on C, C++”
Required Textbook:
• Abraham Silberschatz, Galvin, Gagne “Operating System Concepts”, 9th edition. 2012
• Kay A. Robbins, Steven Robbins, Unix Systems Programming, 2003
Recommended Reference Books:
• Herbert Schildt. Windows 95 Programming in C and C++. 1995
• Herbert Schildt. Windows 2000 Programming from the Ground Up. 2000.
Handout Content:
 1.1. What is an Operating System
 1.2. Computer system types and description
o 1.2.1. Mainframe Computer Systems
 1.2.1.1. Batch Systems
 1.2.1.2. Multiprogrammed Systems
 1.2.1.3. Time Sharing Systems
o 1.2.2. Desktop Systems
o 1.2.3. Multiprocessor Systems
 Tandem, Symmetric, Asymmetric multiprocessor systems
o 1.2.4. Distributed Systems
 1.2.4.1. Client Server Systems
 1.2.4.2. Peer-to-Peer Systems
o 1.2.5. Clustered Systems
o 1.2.6. Real Time Systems
o 1.2.7. Handheld Systems
Textbook - Silberschatz, Chapter 1
Operating System Purpose
Run user(s’) program(s)
3 main responsibilities
 To provide an environment for a computer user to execute
programs on computer hardware in a convenient and efficient
manner
 (Shells, Windows, Terminals, Executable files concept).
 To allocate separate resources (memory, processor, disk space, I/O device
usage) of the computer as needed to solve the problem given.
 The allocation process should be as fair and efficient as possible.
 Control the running programs:
 supervision of the execution of user programs to prevent errors
and improper use of the computer
 protection of OS and programs from user programs
 management of the operation and control of I/O devices
 device drivers, file systems
What is an Operating System ?
• a program that manages the computer hardware
• acts as an intermediary between the user applications and the
computer hardware.
• provides certain services to programs and to the users of those
programs in order to make their tasks possible and easier.
User 1
Compiler
User 2
Assembler
User 3
User n
Text editor
Database System
System and application programs
Operating System
Computer Hardware
Abstract view of the components of a computer system.
What is an Operating System ?
User Application
Programs
Trying to use Computing
Resources
Using ready solutions is
possible (is effective)
API to OS for User
Applications
Operating System
Device drivers
Direct usage is possible (but
is not effective)
Control API to Hardware
Computing
Resources
are provided by
Computer Hardware
(CPU, Memory, I/O
devices)
An application programming interface (API) is a set of functions, procedures, methods or classes that
an operating system, library or service provides to support requests made by computer programs.
Operating-Systems are improved. The principles remain
IoT - The same evolution?
• The newest computers repeat the history of old computers starting from the
very simple software and growing to full multiprocessor OS.
• All OS solutions invented tens of years ago are applicable for newest computers.
Early Computer System and OS types. The
trends.
Mainframe Computer
Systems
Desktop Computer
Systems
Operating Systems
Batch Systems
Multiprogrammed
Systems
Time Sharing
Systems
OS improves
•
••
•
•
••
Tasks are collected in queues.
CPU
and runsin
the
parts of
tasks from queue giving equal or
Taskstakes
are collected
queues
(pools)
similar tasks’ batches
appropriate
time
to each of task
in order
to serve
all tasks from
If
CPUtask
is idle
it takes
(next
previous
unfinished)
task’s
Next
from
batchanother
runs when
theorprevious
one
is finished
fully
the
queue. to be busy all the time
some
CPU ispart
dedicated for one task and is often idle
CPU
tasks afterwhen
equalitorispredefined
CPU switches
switches between
between queue
tasks (programs)
idle and
intervals
time
usually is of
busy
alland
the usually
time. is never idle.
• User interaction with the programs is possible
Mainframe Computer Systems
Batch Systems
Batch of Tasks (Jobs)
CPU
Input
Task #1
Input
Calculation
Output
Save Result
Task #2
Input
Calculation
Output
Save Result
Task #3
Read
Calculation
Output
Save Result
Output
Read
Save
Disksidle. Why ? …
Disadvantage: In this execution environment, the CPU is often
Tapes
Because the speeds of the mechanical I/O devices are intrinsically slower than are those of
electronic devices.
System Evaluation Criteria
 CPU utilization (maximize – keep the CPU as busy as
possible) – the time the CPU is busy during some time period
 Throughput (maximize) - # of processes that complete their
execution per time unit
 Turnaround time (minimize)– amount of time to execute a
particular process
Batch System Evaluation
Task 1
Sec
CPU time. Calculations.
I/O time. Input from the HDD
CPU time. Calculations.
1
2
2
Task 2
Sec
CPU time. Calculations.
I/O time. Input from the HDD
CPU time. Calculations.
I/O time. Print on Printer.
2
1
1
2
Task 3
Sec
CPU time. Calculations.
I/O time. Output to HDD.
CPU time. Calculations.
1
2
1
Overall time for
all 3 tasks to
finish
Through
put
Task1
Turnaround
time
Task2
Turnaround
time
Taks3
Turnaround
time
Average Turnaround
time for all tasks
CPU utilization
15
3/15
5
11
15
(15+11+5)/3 =10.3
8/15 ~53%
Computer System types and description
Mainframe Computer Systems
 were very huge and expensive.
 The expensive system requires the most effective usage
of expensive resources - especially the processor.
 That was why the main purpose of the MainFrame OS was
to utilize the processor by all means.
 Thus appear the Multiprogrammed OS.
Computer System types and description
Mainframe Computer Systems
Multiprogrammed Systems
Advantage: Multiprogramming increases CPU utilization by organizing jobs so that the CPU
CPU
always has one to execute. How ? …
CPU Scheduling
Input
Task #1
Read
Calculation
Output
Output
Read
Task #2
Save
Input
Jobs in
Disadvantage:
Multiprogrammed,
batched systems provided an environment where the
W
Calculation
memory
various system
devices) were utilized
Disks
Outputresources (for example, CPU, memory, peripheral
effectively, but it did not provide for user interaction with the Tapes
computer system.
Task #3
Job Scheduling
Job pool
Read Wait
ontasks
Disk resources
Problems:Calculation
Job and CPU scheduling, Memory management , different
W
protectionOutput
issues should be taken in
account
to keep the system effective.
Memory
management
Time
Resource Protection
MultiProgrammed System Evaluation
Task 1
Sec
CPU time. Calculations.
I/O time. Input from the HDD
CPU time. Calculations.
1
2
2
Resource Usage Table
Multiprogrammed System
The resource is dedicated if it’s free
Average
CPU utilization
and ifTurnaround
there is a request
Overall time for
Through
all 3 tasks to
put
Task 2
finish
Task1
Task2
Taks3
Turnaround
Turnaround Turnaround time for all tasks
Sec time
Seconds
time
time CPU
HDD
Printer
15
5
3/15
CPU time. Calculations.
I/O time. Input from the HDD
CPU time. Calculations.
I/O time. Print on Printer.
2
1
1
2
Task 3
Sec
CPU time. Calculations.
I/O time. Output to HDD.
CPU time. Calculations.
11
15
(15+11+5)/3 =10.3
1
2
3
4
5
6
7
8
9
10
1
2
1
T1
T2
T2
T3
T1
T1
T2
T3
T1
T1
T2
T3
T3
CPU
8/15
~53%
queue
T2,T3
T3
T3
T1
T2
T2
T3
T2
T2
Overall time
for all 3 tasks
to finish
Throug
hput
Task1
Turnaround
time
Task2
Turnaround
time
Task3
Turnaround
time
Average
Turnaround time
for all tasks
CPU
utilization
9
3/9
6
9
8
(6+9+8)/3=7.67
8/9~89%
Multitasking (time sharing) Systems
The CPU executes multiple jobs by switching among them, but the switches occur
Advantage: Users can interact with each program while it is running. How ? …
so frequently that the users can interact with each program while it is running.
Time
Processes in Physical Memory
CPU
Process #1
Input
Calculation
Input
Output
Calculation
Output
Save Result
CPU time sharing
Process concurrent execution
Input
Process #2
Input
Calculation
Output
Save Result
Output
Process #3
Read
Calculation
Output
Physical
Save Result
Memory
Read
Save
Disadvantage: Time-sharing operating systems are even more complex
Disks systems.
(difficult, expensive) than multiprogrammed operating
Users
Security
File system
Virtual
Problems: Job and CPU scheduling, Memory management,
User and
Paging
Security management,
Protection issues should be Memory
taken in account to
Memory management
and protection
keep the system
effective.
Time Sharing System Evaluation
Task 1
Sec
CPU time. Calculations.
I/O time. Input from the HDD
CPU time. Calculations.
1
2
2
Task 2
Sec
CPU time. Calculations.
I/O time. Input from the HDD
CPU time. Calculations.
I/O time. Print on Printer.
2
1
1
2
Task 3
Sec
CPU time. Calculations.
I/O time. Output to HDD.
CPU time. Calculations.
• For external devices if the task takes the resource it
keeps the resource until completing the operation
with it.
Resource Usage Table
Seconds CPU
1
2
3
4
5
6
7
8
9
10
1
2
1
T1
T2
T3
T2
T1
T3
T1
T2
HDD
Printer CPU
queue
HDD
queue
T2,T3
T3
T2
T1
T1
T1
T3
T3
T2
T2
T1
T2
T2
T2
Overall time
for all 3 tasks
to finish
Throug Task1
hput
Turnaround
time
Task2
Turnaround
time
Task3
Turnaround
time
Average
Turnaround time
for all tasks
10
3/10
10
6
(7+10+6)/3 =7.67 8/10 ~80%
7
CPU
utilization
Evaluation of the systems by Criteria
Seconds
Task 1
Sec
CPU time. Calculations.
I/O time. Input from the HDD
CPU time. Calculations.
1
2
2
Task 2
Sec
CPU time. Calculations.
I/O time. Input from the HDD
CPU time. Calculations.
I/O time. Print on Printer.
2
1
1
2
Task 3
Sec
CPU time. Calculations.
I/O time. Output to HDD.
CPU time. Calculations.
Batch
Multiprog
rammed
Time
Sharing
Seco
nds
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
CP
U
T1
HD
D
1
2
3
4
5
6
7
8
9
Print
er
T1
T1
T1
T1
T2
T2
Seconds
T2
1
2
3
4
5
6
7
8
9
10
T2
T2
T2
T3
T3
T3
T3
1
2
1
CPU
T1
T2
T2
T3
T1
T1
T2
T3
CPU
T1
T2
T3
T2
T1
T3
T1
T2
HDD
Printer
CPU queue
T2,T3
T3
T3
T1
T2
T2
T3
T1
T1
T2
T3
T3
T2
T2
HDD
Printer
T1
T1
T3
T3
T2
CPU
queue
T2,T3
T3
T2
T1
HDD
queue
T2
T1
T2
T2
T2
Overall time
for all 3
tasks to
finish
15
Throu
ghput
Task1
Turnaroun
d time
Task2
Turnaroun
d time
Task3
Turnaroun
d time
Average
Turnaround time
for all tasks
CPU
utilization
3/15
5
11
15
(15+11+5)/3=10.3
8/15 ~53%
9
3/9
6
9
8
(6+9+8)/3=7.67
8/9~89%
10
3/10
7
10
6
(7+10+6)/3=7.67
8/10~80%