Transcript Ch 3 PowerPoint Slides

Slide 3-1
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Operating Systems: A Modern Perspective, Chapter 3
Slide 3-2
Operating System
Organization
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3
Operating Systems: A Modern Perspective, Chapter 3
Purpose of an OS
Coordinate Use
of the Abstractions
Processes
The Abstractions
Create the Abstractions
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Operating Systems: A Modern Perspective, Chapter 3
Slide 3-3
OS Requirements
• Provide resource abstractions
– Process abstraction of CPU/memory use
• Address space
• Thread abstraction of CPU within address space
– Resource abstraction
• “Anything a process can request that can block the
process if it is unavailable”
• NT uses “object abstraction” to reference resources
– File abstraction of secondary storage use
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Operating Systems: A Modern Perspective, Chapter 3
Slide 3-4
Slide 3-5
DOS -- Resource Abstraction Only
Program
Program
Libraries
Program
OS Services
ROM Routines
Processor(s)
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Main Memory
Operating Systems: A Modern Perspective, Chapter 3
Devices
Slide 3-6
OS Requirements (cont)
• Provide resource abstractions
• Manage resource sharing
–
–
–
–
Time/space-multiplexing
Exclusive use of a resource
Isolation
Managed sharing
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Operating Systems: A Modern Perspective, Chapter 3
Slide 3-7
Abstraction & Sharing
Process
Program
State
Process
Program
State
Process
Program
State
Libraries
OS Services
• Abstraction
• Manage sharing
Processor(s)
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Main Memory
Operating Systems: A Modern Perspective, Chapter 3
ROM Routines
Devices
Slide 3-8
OS Design Constraints
•
•
•
•
•
•
Performance
Protection and security
Correctness
Maintainability
Commercial factors
Standards and open systems
Copyright © 2004 Pearson Education, Inc.
Operating Systems: A Modern Perspective, Chapter 3
Performance
• The OS is an overhead function  should
not use too much of machine’s resources
• Minimum functionality is to implement
abstractions
• Additional function must be traded off
against performance
– DOS: one process
– UNIX: low level file system
Copyright © 2004 Pearson Education, Inc.
Operating Systems: A Modern Perspective, Chapter 3
Slide 3-9
Protection & Security
Slide 3-10
• Multiprogramming  resource sharing
• Therefore, need software-controlled
resource isolation
• Security policy: Sharing strategy chosen by
computer’s owner
• Protection mechanism: Tool to implement a
family of security policies
Copyright © 2004 Pearson Education, Inc.
Operating Systems: A Modern Perspective, Chapter 3
Correctness & Maintainability
Slide 3-11
• Security depends on correct operation of
software  trusted vs untrusted software
• Maintainability relates to ability of software
to be changed
• If either is sufficiently important, can limit
the function of the OS
– Guiding a manned spaceship
– Managing a nuclear reactor
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Operating Systems: A Modern Perspective, Chapter 3
Device Management
Slide 3-12
Device-Independent
Part
Device-Dependent
Part
Device-Dependent
Part
Device
Device
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Device-Dependent
Part
…
Operating Systems: A Modern Perspective, Chapter 3
Device
Process, Thread, and Resource
Management
Thread
Abstraction
Process
Abstraction
Multiprogramming
Generic
Resource
Manager
Other
Primary
Memory
…
Processor
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Operating Systems: A Modern Perspective, Chapter 3
Abstract
Resources
Slide 3-13
Slide 3-14
Memory Management
Isolation &
Sharing
Process
Manager
Block
Allocation
Virtual
Memory
Primary
Memory
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Operating Systems: A Modern Perspective, Chapter 3
Storage
Devices
Exclusive Access to a Resource
Slide 3-15
Processor
Process A
Process B
A’s Protected
Object
Supervisor
Program
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Operating Systems: A Modern Perspective, Chapter 3
Processor Modes
• Mode bit: Supervisor or User mode
• Supervisor mode
– Can execute all machine instructions
– Can reference all memory locations
• User mode
– Can only execute a subset of instructions
– Can only reference a subset of memory
locations
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Operating Systems: A Modern Perspective, Chapter 3
Slide 3-16
Kernels
Slide 3-17
• The part of the OS critical to correct
operation (trusted software)
• Executes in supervisor mode
• The trap instruction is used to switch from
user to supervisor mode, entering the OS
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Operating Systems: A Modern Perspective, Chapter 3
Supervisor and User Memory
User
Process
User
Space
Supervisor
Process
Supervisor
Space
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Operating Systems: A Modern Perspective, Chapter 3
Slide 3-18
Procedure Call and Message Passing
Operating Systems
send(…, A, …);
receive(…, B, …);
call(…);
trap
send/receive
return;
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receive(…A, …);
…
send(…, B, …);
Operating Systems: A Modern Perspective, Chapter 3
Slide 3-19
System Call Using the trap Instruction
Slide 3-20
…
fork();
…
Trap Table
fork() {
…
trap
N_SYS_FORK()
…
}
Kernel
sys_fork()
sys_fork() {
/* system function */
…
return;
}
Copyright © 2004 Pearson Education, Inc.
Operating Systems: A Modern Perspective, Chapter 3
A Thread Performing a System Call
User Space
Kernel Space
Thread
fork();
sys_fork() {
}
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Operating Systems: A Modern Perspective, Chapter 3
Slide 3-21
Basic Operating System
Organization
File
Manager
Process, Thread &
Resource Manager
Processor(s)
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Slide 3-22
Memory
Manager
Device
Manager
Main Memory
Devices
Operating Systems: A Modern Perspective, Chapter 3
Slide 3-23
The UNIX Architecture
Interactive User
Application
…
Programs
OS System Call Interface
Commands
Device Driver
Device Driver
…
Device Driver
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Driver Interface
Libraries
Trap Table
Monolithic Kernel Module
•Process Management
•Memory Management
•File Management
•Device Mgmt Infrastructure
Operating Systems: A Modern Perspective, Chapter 3
Slide 3-24
Microkernel Organization
Process
Process
Process
Libraries
User
Supervisor
Server
Server
Server
Device Drivers
Microkernel
Processor(s)
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Main Memory
Operating Systems: A Modern Perspective, Chapter 3
Devices
Windows NT Organization
T
Process
T
T
T
Process
Slide 3-25
Process
T
T
T
T
Process Management
Memory Management
File Management
Subsystem
Subsystem
Device Mgmt Infrastructure
T
Libraries
Subsystem
User
Supervisor
NT Executive
NT Kernel
Hardware Abstraction Layer
Processor(s)
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Main Memory
Operating Systems: A Modern Perspective, Chapter 3
I/O Subsystem
Devices
Slide 3-26
Monitoring the Kernel
T
Process
Task
Manager
T
T
T
Process
Process
T
T
T
T
T
pview
Libraries
pstat
Subsystem
Subsystem
Subsystem
User
Supervisor
NT Executive
NT Kernel
Hardware Abstraction Layer
Processor(s)
Copyright © 2004 Pearson Education, Inc.
Main Memory
Operating Systems: A Modern Perspective, Chapter 3
I/O Subsystem
Devices