Matakuliah
Tahun
Versi
: H0344/Organisasi dan Arsitektur Komputer
: 2005
: 1/1
Pertemuan 13
Operating System 1
1
Learning Outcomes
Pada akhir pertemuan ini, diharapkan mahasiswa
akan mampu :
• Menghubungkan prinsip-prinsip
scheduling proses komputasi
2
Outline Materi
• Overview
• Scheduling
3
Overview
An operating system is a program that controls the execution
of application programs and acts as an interface between the
user of a computer and the computer hardware.
It can be thought of as having two objectives:
• Convenience
• Efficiency
4
Overview
Layers and views of computer system
End user
Programmer
Application program
Operating
system
designer
Utilities
Operating system
Computer hardware
5
Overview
The operating system typically provides services in the
following areas:
• Program creation
• Program execution
• Access to I/O devices
• Control access to files
• System access
• Error detection and response
• Accounting
6
Overview
The operating system as resource manager
Computer system
Operating
system
software
I/O devices
Printers,
keyboards,
digital camera,
etc
I/O controller
I/O controller
Programs
and data
I/O controller
Processor
Processor
OS
Program
Data
7
Overview
Memory layout for a resident monitor
Interrupt
processing
Device
drivers
Monitor
Job
sequencing
Control language
interpreter
Boundary
User
program
area
8
Overview
Multiprogramming
batch systems
Run
Run
Wait
Wait
time
(a) Uniprogramming
Program A
Run
Program B
Wait
Run
Run
A
Run
B
Run
Wait
Wait
Wait
Run
A
Wait
Run
Wait
Run
B
Wait
time
(a) Multiprogramming with two program
Program A
Run
Program B
Wait
Program C
Run
Wait
Run
A
Run
Wait
Run
B
Run
Wait
Run
Run
C
Wait
Wait
Wait
Run
A
Run
B
Wait
Run
Wait
Run
C
Wait
time
(a) Multiprogramming with three program
9
Overview
Batch multiprogramming versus time sharing
Batch multiprogramming
Time sharing
Principal objective
Maximize processor use
Minimize response time
Source of directives
to operating system
Job control language
commands provided with
the job
Command entered at
the terminal
10
Scheduling
Type of scheduling
Long term scheduling
The decision to add to the pool of processes to be executed
Medium term scheduling
The decision to add to the number of processes that are
partially or fully in main memory
Short term scheduling
The decision as to which available process will be executes
by the processor
I/O scheduling
The decision as to which process’s pending I/O request shall
be handled by an available I/O device
11
Scheduling
Five state process model
New
Admit
Dispatch
Ready
Running
Release
Exit
Timeout
Event occurs
Event wait
Blocked
12
Scheduling
Identifier
State
Process control block
Priority
Program counter
Memory pointer
Context data
I/O status information
Accounting
information
13
Scheduling
Example
Operating system
Operating system
Operating system
In control
Service handler
Service handler
Scheduler
Interrupt handler
A “Running”
Scheduler
Interrupt handler
Service handler
Scheduler
Interrupt handler
A “Waiting”
A “Waiting”
B “Ready”
B “Running”
In control
B “Ready”
In control
Other partition
Other partition
Other partition
14
Scheduling
Key elements of an operating system for multiprogramming
Operating system
Service call
from process
Interrupt from
process
Interrupt from
I/O
Service call
handler
(code)
Interrupt
handler
(code)
Longterm
queue
Shortterm
queue
I/O
queue
Short-term
scheduler
(code)
Pass control to
process
15
Scheduling
Queuing diagram representation of processor scheduling
Long term queue
Short term queue
End
Processor
I/O1 occurs
I/O1 queue
I/O2 occurs
I/O2 queue
I/On occurs
I/On queue
16