Operating System Overview

Август 6, 2022

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Operating System Overview

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2. Outline Major achievements The process Memory management Information protection and security Scheduling and resource management System
3. Major Achievements There have been 5 major advances in the development of OSs: Processes Memory management
4. Outline Major achievements The process Memory management Information protection and security Scheduling and resource management System
5. Process This term was first used by the designers of Multics in the 1960s Definitions A
6. Difficulties with Designing System Software Problems in timing and synchronization that contributed to the development of
7. Difficulties with Designing System Software Problems in timing and synchronization that contributed to the development of
8. Difficulties with Designing System Software Problems in timing and synchronization that contributed to the development of
9. Difficulties with Designing System Software The principal tool available to system programmers in developing the early
10. Difficulties with Designing System Software The design turned out to be remarkably difficult many jobs in
11. Difficulties with Designing System Software Vulnerability to subtle programming errors Effects of these errors could be
12. Difficulties with Designing System Software Improper synchronization - a routine must be suspended awaiting an event
13. Difficulties with Designing System Software Nondeterminate program operation the results of a particular program depend on
14. Process Systematic way to monitor and control the various programs executing on the processor is needed
15. Process The execution context, or process state is the internal data by which the OS is
16. Process The context includes all the information that the OS needs to manage the process the
17. Typical process implementation Two processes A and B exist in the portions of main memory A
18. Typical process implementation The process index register contains the index into the process currently controlling the
19. Typical process implementation The base register is the starting address of the region in the memory
20. Process Process is realized as a data structure Process can be executing or awaiting execution The
21. Outline Major achievements The process Memory management Information protection and security Scheduling and resource management System
22. Memory Management Storage management responsibilities: Process isolation Automatic allocation and management Support of modular programming Protection
23. Virtual Memory OS meets these requirements with virtual memory and file system facilities. File system implements
24. Paging Processes vary in size If the processor switches among a number of processes, it is
25. Virtual Memory
26. Virtual Memory Addressing
27. Outline Major achievements The process Memory management Information protection and security Scheduling and resource management System
28. Information Protection and Security Availability Concerned with protecting the system against interruption Confidentiality Assuring that users
29. Information Protection and Security Data integrity Protection of data from unauthorized modification Authenticity Concerned with the
30. Outline Major achievements The process Memory management Information protection and security Scheduling and resource management System
31. Scheduling and Resource Management Fairness Give equal and fair access to resources Differential responsiveness Discriminate among
32. Scheduling and Resource Management Efficiency Maximize throughput, minimize response time, and accommodate as many uses as
33. Key Elements of an Operating System
34. Outline Major achievements The process Memory management Information protection and security Scheduling and resource management System
35. System Structure View the system as a series of levels Each level performs a related subset
36. Levels Level 1 Electronic circuits Objects are registers, memory cells, and logic gates Operations are clearing
37. Levels Level 3 Adds the concept of a procedure or subroutine, plus call/return operations Level 4
38. Concepts Related to Multiprogramming Level 5 Process as a program in execution Suspend and resume processes
39. Concepts Related to Multiprogramming Level 7 Creates logical address space for processes Organizes virtual address space
40. Deal with External Objects Level 8 Communication of information and messages between processes Level 9 Supports
41. Deal with External Objects Level 11 Responsible for maintaining the association between the external and internal
42. Outline Major achievements The process Memory management Information protection and security Scheduling and resource management System
43. Modern Operating Systems Microkernel architecture Assigns only a few essential functions to the kernel Address spaces
44. Modern Operating Systems Multithreading Process is divided into threads that can run concurrently Thread Dispatchable unit
45. Modern Operating Systems Symmetric multiprocessing (SMP) There are multiple processors These processors share same main memory
46. Multiprogramming and Multiprocessing
47. Modern Operating Systems Distributed operating systems Provides the illusion of a single main memory space and
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Слайд 2

Outline
Major achievements
The process
Memory management
Information protection and security
Scheduling and resource management
System structure
Developments

leading to modern OSs

Слайд 3

Major Achievements
There have been 5 major advances in the development of

OSs:
Processes
Memory management
Information protection and security
Scheduling and resource management
System structure

Слайд 4

Outline
Major achievements
The process
Memory management
Information protection and security
Scheduling and resource management
System structure
Developments

leading to modern OSs

Слайд 5

Process
This term was first used by the designers of Multics in

the 1960s
Definitions
A program in execution
An instance of a program running on a computer
The entity that can be assigned to and executed on a processor
A unit of activity characterized by
a single sequential thread of execution
a current state
an associated set of system resources

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Difficulties with Designing System Software
Problems in timing and synchronization that contributed

to the development of the concept of the process:
Multiprogramming
Key design objective: to keep the processor and I/O devices simultaneously busy to achieve maximum efficiency.
Key mechanism: in response to signals indicating the completion of I/O transactions, the processor is switched among the various programs residing in main memory.

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Difficulties with Designing System Software
Problems in timing and synchronization that contributed

to the development of the concept of the process:
General purpose time-sharing
Key design objective: to be responsive to the needs of the individual user be able to support many users simultaneously
Key mechanism: typical user needs an average 2 seconds of processing time per minute, then close to 30 such users should be able to share the same system without noticeable interference

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Difficulties with Designing System Software
Problems in timing and synchronization that contributed

to the development of the concept of the process:
Real-time transaction processing systems
Key design objective: a number of users are entering queries or updates against a database (example: an airline reservation system)
Key mechanism: response time is very important

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Difficulties with Designing System Software
The principal tool available to system programmers

in developing the early multiprogramming and multiuser interactive systems – interrupt
the activity of any job could be suspended
by a definite event or an I/O completion
the processor would
save some sort of context (PC and other registers)
branch to an interrupt-handling routine
an interrupt-handling routine would
determine the nature of the interrupt
process the interrupt
resume user processing with the interrupted job

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Difficulties with Designing System Software
The design turned out to be remarkably

difficult
many jobs in progress at any one time
each job involved numerous steps to be performed in sequence
=> it became impossible to analyze all of the
possible combinations of sequences of events
The absence of
some systematic means of coordination and cooperation among activities
Programmers used methods based on their understanding of the environment that the OS had to control

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Difficulties with Designing System Software
Vulnerability to subtle programming errors
Effects of these

errors could be observed only when certain relatively rare sequences of actions occurred
These errors were difficult to diagnose they needed to be distinguished from application software errors and hardware errors
Even when the error was detected, it was difficult to determine the cause, because the precise conditions under which the errors appeared were very hard to reproduce
There 4 main causes of such errors

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Difficulties with Designing System Software
Improper synchronization -
a routine must be

suspended awaiting an event elsewhere in the system
a signal from some other routine is required
improper design of the signaling mechanism: lost signals, duplicate signals received
Failed mutual exclusion
multiple programs using shared resources at the same time
mechanism that permits only one routine at a time to perform an update against file

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Difficulties with Designing System Software
Nondeterminate program operation
the results of a particular

program depend on the input to that program
not on the activities of other programs in shared memory (overwriting common memory areas)
the order in which various programs are scheduled may affect the outcome of any particular program
Deadlocks
two or more programs hung up waiting for each other

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Process
Systematic way to monitor and control the various programs executing on

the processor
is needed to tackles these problems
Process consists of three components
an executable program
the associated data needed by the program
variables
work space
buffers, etc.
the execution context of the program

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Process
The execution context, or process state
is the internal data by which

the OS is able to supervise and control the process
This internal information is separated from the process
because the OS has information not permitted to the process

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Process
The context includes all the information that
the OS needs to manage

the process
the processor needs to execute the process properly
The context includes
the contents of the various processor registers (PC, data registers)
information of use to the OS
priority of the process
whether the process is waiting for the completion of a particular I/O event

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Typical process implementation
Two processes A and B exist in the portions

of main memory
A block of memory is allocated to each process, contains
program
data
context
An OS builds and maintains a process list with one entry for each process
a pointer to the location of the block of memory that contains the process
a part or all of the execution context of the process

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Typical process implementation
The process index register contains the index into the

process currently controlling the processor
The program counter points to the next instruction in the process to be executed
The base register and limit register define the region in memory occupied by the process

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Typical process implementation
The base register is the starting address of the

region in the memory
The limit register is the size of the region (in bytes or words)
The program counter and all data references are
interpreted relative to the base register
must not exceed the value in the limit register
this prevents interprocess interference

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Process
Process is realized as a data structure
Process can be executing or

awaiting execution
The entire state of the process at any instant is contained in its context
This structure allows the development of powerful techniques for ensuring coordination and cooperation among processes

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Outline
Major achievements
The process
Memory management
Information protection and security
Scheduling and resource management
System structure
Developments

leading to modern OSs

Слайд 22

Memory Management
Storage management responsibilities:
Process isolation
Automatic allocation and management
Support of modular programming
Protection

and access control
Long-term storage

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Virtual Memory
OS meets these requirements with virtual memory and file system

facilities.
File system implements long-term store
Information stored in named objects called files
Virtual memory allows programs to address memory from a logical point of view, without regard to the amount of main memory physically available

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Paging
Processes vary in size
If the processor switches among a number

of processes, it is difficult to pack them compactly into main memory
Paging systems allow process to be comprised of a number of fixed-size blocks, called pages
Virtual address is a page number and an offset within the page
Each page may be located anywhere in main memory
Real address or physical address is the main memory address

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Virtual Memory

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Virtual Memory Addressing

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Outline
Major achievements
The process
Memory management
Information protection and security
Scheduling and resource management
System structure
Developments

leading to modern OSs

Слайд 28

Information Protection and Security
Availability
Concerned with protecting the system against interruption
Confidentiality
Assuring that

users cannot read data for which access is unauthorized

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Information Protection and Security
Data integrity
Protection of data from unauthorized modification
Authenticity
Concerned with

the proper verification of the identity of users and the validity of messages or data

Слайд 30

Outline
Major achievements
The process
Memory management
Information protection and security
Scheduling and resource management
System structure
Developments

leading to modern OSs

Слайд 31

Scheduling and Resource Management
Fairness
Give equal and fair access to resources
Differential responsiveness
Discriminate

among different classes of jobs

Слайд 32

Scheduling and Resource Management
Efficiency
Maximize throughput, minimize response time, and accommodate as

many uses as possible

Слайд 33

Key Elements of an Operating System

Слайд 34

Outline
Major achievements
The process
Memory management
Information protection and security
Scheduling and resource management
System structure
Developments

leading to modern OSs

Слайд 35

System Structure
View the system as a series of levels
Each level performs

a related subset of functions
Each level relies on the next lower level to perform more primitive functions
This decomposes a problem into a number of more manageable subproblems

Слайд 36

Levels
Level 1
Electronic circuits
Objects are registers, memory cells, and logic gates
Operations are

clearing a register or reading a memory location
Level 2
Processor’s instruction set
Operations such as add, subtract, load, and store

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Levels
Level 3
Adds the concept of a procedure or subroutine, plus call/return

operations
Level 4
Interrupts
Not part of the OS, constitute the processor hardware

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Concepts Related to Multiprogramming
Level 5
Process as a program in execution
Suspend and

resume processes
Level 6
Secondary storage devices
Transfer of blocks of data

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Concepts Related to Multiprogramming
Level 7
Creates logical address space for processes
Organizes virtual

address space into blocks
OS deals with the resources of a single processor

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Deal with External Objects
Level 8
Communication of information and messages between processes
Level

9
Supports long-term storage of named files
Level 10
Provides access to external devices using standardized interfaces

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Deal with External Objects
Level 11
Responsible for maintaining the association between the

external and internal identifiers
Level 12
Provides full-featured facility for the support of processes
Level 13
Provides an interface to the OS for the user
Hypothetical model of an OS:
provides useful descriptive structure
serves as an implementation guideline

Слайд 42

Outline
Major achievements
The process
Memory management
Information protection and security
Scheduling and resource management
System structure
Developments

leading to modern OSs

Слайд 43

Modern Operating Systems
Microkernel architecture
Assigns only a few essential functions to the

kernel
Address spaces
Interprocess communication (IPC)
Basic scheduling

Слайд 44

Modern Operating Systems
Multithreading
Process is divided into threads that can run concurrently
Thread
Dispatchable

unit of work
executes sequentially and is interruptable
Process is a collection of one or more threads

Слайд 45

Modern Operating Systems
Symmetric multiprocessing (SMP)
There are multiple processors
These processors share same

main memory and I/O facilities
All processors can perform the same functions

Слайд 46

Multiprogramming and Multiprocessing

Слайд 47

Modern Operating Systems
Distributed operating systems
Provides the illusion of a single main

memory space and single secondary memory space

Operating System Overview

Содержание

OutlineMajor achievementsThe processMemory managementInformation protection and securityScheduling and resource managementSystem structureDevelopments

Major AchievementsThere have been 5 major advances in the development of

OutlineMajor achievementsThe processMemory managementInformation protection and securityScheduling and resource managementSystem structureDevelopments

ProcessThis term was first used by the designers of Multics in

Difficulties with Designing System SoftwareProblems in timing and synchronization that contributed

Difficulties with Designing System SoftwareProblems in timing and synchronization that contributed

Difficulties with Designing System SoftwareProblems in timing and synchronization that contributed

Difficulties with Designing System SoftwareThe principal tool available to system programmers

Difficulties with Designing System SoftwareThe design turned out to be remarkably

Difficulties with Designing System SoftwareVulnerability to subtle programming errorsEffects of these

Difficulties with Designing System SoftwareImproper synchronization - a routine must be

Difficulties with Designing System SoftwareNondeterminate program operationthe results of a particular

ProcessSystematic way to monitor and control the various programs executing on

ProcessThe execution context, or process stateis the internal data by which

ProcessThe context includes all the information thatthe OS needs to manage

Typical process implementationTwo processes A and B exist in the portions

Typical process implementationThe process index register contains the index into the

Typical process implementationThe base register is the starting address of the

ProcessProcess is realized as a data structureProcess can be executing or

OutlineMajor achievementsThe processMemory managementInformation protection and securityScheduling and resource managementSystem structureDevelopments

Memory ManagementStorage management responsibilities:Process isolationAutomatic allocation and managementSupport of modular programmingProtection

Virtual MemoryOS meets these requirements with virtual memory and file system

PagingProcesses vary in size If the processor switches among a number

Virtual Memory

Virtual Memory Addressing

OutlineMajor achievementsThe processMemory managementInformation protection and securityScheduling and resource managementSystem structureDevelopments

Information Protection and SecurityAvailabilityConcerned with protecting the system against interruptionConfidentialityAssuring that

Information Protection and SecurityData integrityProtection of data from unauthorized modificationAuthenticityConcerned with

OutlineMajor achievementsThe processMemory managementInformation protection and securityScheduling and resource managementSystem structureDevelopments

Scheduling and Resource ManagementFairnessGive equal and fair access to resourcesDifferential responsivenessDiscriminate

Scheduling and Resource ManagementEfficiencyMaximize throughput, minimize response time, and accommodate as

Key Elements of an Operating System

OutlineMajor achievementsThe processMemory managementInformation protection and securityScheduling and resource managementSystem structureDevelopments

System StructureView the system as a series of levelsEach level performs

LevelsLevel 1Electronic circuitsObjects are registers, memory cells, and logic gatesOperations are

LevelsLevel 3Adds the concept of a procedure or subroutine, plus call/return

Concepts Related to MultiprogrammingLevel 5Process as a program in executionSuspend and

Concepts Related to MultiprogrammingLevel 7Creates logical address space for processesOrganizes virtual

Deal with External ObjectsLevel 8Communication of information and messages between processesLevel

Deal with External ObjectsLevel 11Responsible for maintaining the association between the

OutlineMajor achievementsThe processMemory managementInformation protection and securityScheduling and resource managementSystem structureDevelopments

Modern Operating SystemsMicrokernel architectureAssigns only a few essential functions to the

Modern Operating SystemsMultithreadingProcess is divided into threads that can run concurrentlyThreadDispatchable

Modern Operating SystemsSymmetric multiprocessing (SMP)There are multiple processorsThese processors share same

Multiprogramming and Multiprocessing

Modern Operating SystemsDistributed operating systemsProvides the illusion of a single main

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Problems in timing and synchronization that contributed

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Difficulties with Designing System Software
Problems in timing and synchronization that contributed

Difficulties with Designing System Software
The principal tool available to system programmers

Difficulties with Designing System Software
The design turned out to be remarkably

Difficulties with Designing System Software
Vulnerability to subtle programming errors
Effects of these

Difficulties with Designing System Software
Improper synchronization -
a routine must be

Difficulties with Designing System Software
Nondeterminate program operation
the results of a particular

Process
Systematic way to monitor and control the various programs executing on

Process
The execution context, or process state
is the internal data by which

Process
The context includes all the information that
the OS needs to manage

Typical process implementation
Two processes A and B exist in the portions

Typical process implementation
The process index register contains the index into the

Typical process implementation
The base register is the starting address of the

Process
Process is realized as a data structure
Process can be executing or

Outline
Major achievements
The process
Memory management
Information protection and security
Scheduling and resource management
System structure
Developments

Memory Management
Storage management responsibilities:
Process isolation
Automatic allocation and management
Support of modular programming
Protection

Virtual Memory
OS meets these requirements with virtual memory and file system

Paging
Processes vary in size
If the processor switches among a number

Outline
Major achievements
The process
Memory management
Information protection and security
Scheduling and resource management
System structure
Developments

Information Protection and Security
Availability
Concerned with protecting the system against interruption
Confidentiality
Assuring that

Information Protection and Security
Data integrity
Protection of data from unauthorized modification
Authenticity
Concerned with

Outline
Major achievements
The process
Memory management
Information protection and security
Scheduling and resource management
System structure
Developments

Scheduling and Resource Management
Fairness
Give equal and fair access to resources
Differential responsiveness
Discriminate

Scheduling and Resource Management
Efficiency
Maximize throughput, minimize response time, and accommodate as

Outline
Major achievements
The process
Memory management
Information protection and security
Scheduling and resource management
System structure
Developments

System Structure
View the system as a series of levels
Each level performs

Levels
Level 1
Electronic circuits
Objects are registers, memory cells, and logic gates
Operations are

Levels
Level 3
Adds the concept of a procedure or subroutine, plus call/return

Concepts Related to Multiprogramming
Level 5
Process as a program in execution
Suspend and

Concepts Related to Multiprogramming
Level 7
Creates logical address space for processes
Organizes virtual

Deal with External Objects
Level 8
Communication of information and messages between processes
Level

Deal with External Objects
Level 11
Responsible for maintaining the association between the

Outline
Major achievements
The process
Memory management
Information protection and security
Scheduling and resource management
System structure
Developments

Modern Operating Systems
Microkernel architecture
Assigns only a few essential functions to the

Modern Operating Systems
Multithreading
Process is divided into threads that can run concurrently
Thread
Dispatchable

Modern Operating Systems
Symmetric multiprocessing (SMP)
There are multiple processors
These processors share same

Modern Operating Systems
Distributed operating systems
Provides the illusion of a single main