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OS > Midterm > Flashcards

Midterm Flashcards

1
Q

What does the operating system do?

A

The OS abstracts the internal computer architecture and the OS manages and transparently handles all of the HW resources.

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2
Q

‘Top Down’ view is associated with?

A

Abstraction (provides a clean and abstract set of resources

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3
Q

‘Bottom-up’ view is associated with?

A

Management (Mangages HW resources)

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4
Q

What does the Disk Driver do?

A

Deals with the hardware and provides an interface to read and write disk blocks

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5
Q

The OS interacts with the device via

A

Device Driver

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6
Q

What is multiplexing

A

Sharing resources in two different ways: in time and in space

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7
Q

What was Generation 0 called

A

Mechanical Era

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8
Q

What’s Generation 1

A

(1945-55) which consisted of the Electromechanical Relays & Vacuum Tubes Era

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9
Q

What’s Generation 2

A

(1955-65) which consisted of the Transistors & Batch Systems Era

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10
Q

What’s Generation 3

A

(1965-1980s) which brought solid-state IC revolution and Multiprogramming

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11
Q

What’s Generation 4

A

(1980-1990) which brought “Personal” Computers.

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12
Q

What’s Generation 5

A

(1990-Present) which brought Mobile Computers

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13
Q

Which generation was the ENIAC created

A

Generation 1

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14
Q

Where was the transistor invented?

A

AT&T’s Bell Labs.(Generation 2)

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15
Q

Leading to the first class of general-purpose computers known as

A

Mainframe

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16
Q

Mainframe?

A

Is a computer system that is primarily used by large organizations or institutions for bulk data processing and large-scale transactions

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17
Q

What was the batch system analogous to

A

Pipelining

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18
Q

Job input (Generation 2)

A

Each user’s “job” was specified by a set of input punch cards

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19
Q

What did the punch cards represent

A

The cards represented the user’s ‘program’

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20
Q

With the 360 what did it bring fourth

A

Multiprogramming,Dynamic Address Translation (DAT),Out-of-Order Instruction Execution

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21
Q

Time-sharing

A

allows the mainframe to be ‘multiplexed’ so that multiple users could issue commands interactively while the system mostly sat idle

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22
Q

The principal components of any computer system consist of

A

CPU, cache memories + MMU, Memory Subsystem (aka primary storage, I/O Devices, long term secondary storage, bus structure

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23
Q

I/O is composed of?

A

a physical device and a device controller

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24
Q

bus structure is?

A

connect all the computer’s subsystems.

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25
Q

What’s the brain of the Comptuer

A

CPU

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26
Q

What does the CPU do

A

F-D-X Fetch Decode Xecute in cycles

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27
Q

Two predominant types of instruction encoding and sets?

A

RISC & CISC

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28
Q

The Program Counter (PC) is?

A

A register, which points to the next instruction to be fetched

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29
Q

Stack Pointer (SP) ?

A

points to the top-of-stack

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30
Q

Frame Pointer (FP)

A

An additional register dedicated for accessing elements within the current frame. Works with Stack pointer

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31
Q

Register file (RF)

A

A set of temporary working (main) registers

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32
Q

RF + SP + PC = ??

A

Execution Context

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33
Q

Program Status Word (PSW)

A

This register contains the condition code bits, which are set by comparison instructions

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34
Q

Execution Context

A

the internal data by which the OS is able to supervise and control the process

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35
Q

Spooling?

A

Whenever a running job finished, the operating system could load a new job from the disk into the now-empty partition and run it is called what?

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36
Q

Has unrestricted access to all computing resources

A

Kernal Mode

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37
Q

Has very restricted access to computing resources

A

User Mode

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38
Q

SMT(Simultaneous Multithreating/Hyperthreading does parrelism

A

No actually it just looks like it

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39
Q

TRAP instructions are

A

The operating system calls functions

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40
Q

Voluntary switches between User and Kernal modes occur…

A

often occur as a result of executing a special instruction called a ‘TRAP’ instruction.

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41
Q

Involuntary changes in operating mode occur as a result of either

A

synchronous (aka exceptions) or asynchronous (aka Interrupts) events,

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42
Q

What type event is the I/0 interupt

A

Async

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43
Q

the time it takes the ‘head’ to slide towards the track containing the data

A

Seek Time

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44
Q

The time for the ‘head’ to find its way to the beginning of the desired sector

A

Latency

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45
Q

The amount of digital data that’s moved from one place to another in a given time

A

Transfer Rate

46
Q

This counts the time from when the data is requested until its fully ‘retrieved’

A

Access Time

47
Q

this is much FASTER overall access times and more energy-efficient than a HDD

A

Solid State Drive

48
Q

This is component that the CPU actually interacts with

A

Device Controller

49
Q

How does the Device controller interact with the CPU

A

As interface between the computer system (operating system) and I/O devices

50
Q

Like a ‘communication system’ that transfers data between system components and subsystems inside a computer

A

Bus

51
Q

address bus + data bus + control bus = ??

A

computer system

52
Q

is a program in execution?

A

Process

53
Q

Allows processes to communicate or ‘sync up’

A

Interprocess Communication (IPC)

54
Q

this determines the method of how files can be structured, represented, stored and retrieved UI

A

File System

55
Q

Makes up Terminal

A

I/O + Shell

56
Q

How applications ask the OS to do things in its behalf

A

A ‘system-call’ Interface (I/F)

57
Q

ALL memory segments/chunks/regions which the process ‘owns’ and that it can read/write from/to

A

Address space

58
Q

(interrupts and halts) the current proces

A

Preempts

59
Q

A finite amount of time in which it is allowed to run

A

time quantum

60
Q

The part of the OS responsible for making these decisions

A

OS scheduler

61
Q

The OS maintains a list of all ‘ready processes’ in a special data structure

A

Process Table

62
Q

INIT and has a PID of

A

1

63
Q

Is the ‘view’ that each process has about its address space

A

Virtual memory

64
Q

an abstraction of data and/or devices, as well as its representation and device-dependent details

A

File

65
Q

UID

A

User ID

66
Q

UID is

A

a person who has access to a system

67
Q

GID stands for

A

Group ID

68
Q

GID is

A

A collection of files that are associated with each other

69
Q

PPID stands for

A

Parent Process ID

70
Q

What does a process always have

A

PPID and PID

71
Q

PID is

A

Process ID

72
Q

$ cat < myfile.txt | sort > myfile_sortex.txt is an example of

A

command pipeline

73
Q

consists of a series of ‘wrapper functions’ (written in C) that contain architecture-dependent assembly

A

System-call interface (SCI).

74
Q

This kernel runs the entire OS as a single program in kernel mode in a singe address space

A

monolithic kernel.

75
Q

this kernel attempts to place as little as possible in the kernel

A

microkernel

76
Q

The microkernel

A

pushes as much as it can out into ‘userland’.

77
Q

The layer kernel

A

breaks up the operating system into different layers and retains much more control on the system

78
Q

This model distinguishes between two types of process client processes and server processes.

A

Client-server Model

79
Q

This kernel allocates direct H/W resources to programs. Manages allocated resources to prevent conflicts

A

Exokernel

80
Q

What does fork() do

A

Create a new process

81
Q

When a child process terminates normally it becomes a

A

Zombie

82
Q

single sequential flow of activities being executed in a processis called?

A

Thread

83
Q

switching from one program to another

A

Context Switch

84
Q

What is N:1 Implementation

A

Single kernel thread is available to work on behalf of each user process

85
Q

What is 1:1 Implementation

A

One user-space thread assigned Kernel resource

86
Q

What is N:M Implementation

A

Each kernel resource can be associated with multiple user-level threads

87
Q

Scheduler Activations is an example of

A

is an example of “many-to-many” N:M (Hybrid) kernel-mapping implementation.

88
Q

Scheduler Activation is

A

provide kernel-level thread functionality with user-level thread flexibility and performance

89
Q

The signal that is given to the thread library From kernel-space to user-space

A

Upcall

90
Q

The arrival of a message causes the system to create a new thread to handle the message is called

A

Pop Up Thread

91
Q

create_global()

A

Creates a global variable that will be stored by way of a ‘pointer’ in the heap

92
Q

set_global()

A

To set its value.

93
Q

thread-local globals

A

‘global’ variables whose ‘scope’ is limited to the thread.

94
Q

read_global()

A

To obtain the pointer of the global var

95
Q

multiple invocations of the procedure can safely be carried out is this type of function

A

Reentrant

96
Q

when only ONE line of execution can be within the procedure is this type of function

A

Non-reentrant

97
Q

A situation that can occur when a low-priority task is holding a resource such as a semaphore for which a higher-priority task is waiting

A

priority inversion problem

98
Q

‘integer variable’ to count the number of pending ‘wake-ups’ for future use

A

semaphore

99
Q

a synchronization mechanism that has two states ‘locked’ (1) or ‘unlocked’ (0)

A

mutex

100
Q

This method of interprocess communication uses two primitives, send and receive

A

Message Passing

101
Q

A block at the end of a phase to make all processes wait until all processes are done

A

Barrier

102
Q

This type of resource can be ‘forcibly’ taken away from the process with no ill effects

A

Preemptible

103
Q

This type of resource CANNOT be taken away safely w/o causing some potential failure.

A

Non-preemptible

104
Q

This is when no process can can operate due to a shared resource not being available

A

Deadlock

105
Q

Conditions for Resource Deadlock

A
  1. Mutal Exclusion
  2. Hold-and-Wait
  3. No-preemption
  4. Circular Wait Condition
106
Q

Do all four conditions for deadlock need to be present for a deadlock to occur

A

If one item is absent, NO resource deadlock is possible.

107
Q

What algorithm just tells you to ignore the problem

A

The Ostrich Algorithm

108
Q

What ways can the OS recover after the detection of a deadlock

A
  1. Preemption
  2. Recovery by voluntarily being ‘nice’
  3. Recovery through ‘Rollback’
  4. Process Killing
109
Q

What is ‘Rollback’

A

‘checkpoint’ mechanism for processes which writes information about a process on a file so that it can
be restarted again

110
Q

When to Look for Deadlocks?

A

Keep an ‘eye’ on CPU utilization and check when it falls below a certain threshold.

111
Q
A

OS (2 decks)

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