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OS Concepts (Ozbirn) > Chapter 9 (Uniprocessor Scheduling) > Flashcards

Chapter 9 (Uniprocessor Scheduling) Flashcards

1
Q

What does the long-term scheduler do?

A

Decides when to admit a process into the ready queue

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2
Q

What does the medium-term scheduler do?

A

Decides when to swap processes in and out of memory

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3
Q

What does the short-term scheduler do?

A

Decides which ready process to execute next

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4
Q

What two decisions does the long-term scheduler make?

A

Whether to admit a new process to the system

Which process to admit

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5
Q

T/F Medium-term scheduling can further manage the degree of multi programming

A

T

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6
Q

What is short-term scheduling also known as?

A

Dispatcher

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7
Q

What is user-oriented criteria?

A

Things the user sees

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8
Q

What is system-oriented criteria?

A

System concerns

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9
Q

What are some user-oriented performance-related criteria?

A

Turnaround time

Response time

Deadlines

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10
Q

What is a user-oriented other criteria?

A

Predictability

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11
Q

What are some system-oriented performance related criteria?

A

Throughput

Processor utilization

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12
Q

What are some system-oriented other criteria?

A

Fairness

Enforcing priorities

Balancing resources

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13
Q

What is a solution to prevent starving lower priority processes?

A

Aging a lower priority to a higher priority until it can eventually run

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14
Q

What is the selection function?

A

Which process runs next

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15
Q

What is the decision mode?

A

When to run the selection function

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16
Q

What are two approaches for decision mode?

A

Non-preemptive

Preemptive

17
Q

Which scheduling algorithms are preemptive?

A

Round Robin (at timeout)

Feedback (at timeout)

Shortest remaining time (at arrival)

18
Q

Which scheduling algorithms are non-preemptive?

A

First come first serve

Shortest process next

Highest response ratio next

19
Q

What are the selection functions for:

Feedback

SPN

HRRN

RR

SRT

FCFS

A

N/A

min(s)

max((w+s)/s)

constant

min(s-e)

max(w)

20
Q

Which scheduling algorithms have the potential for starvation?

A

SPN

SRT

Feedback

21
Q

What jobs does RR favor?

A

Processor bound

22
Q

What is a virtual RR scheduler?

A

Separate queue for processes returning from I/O and favor them

23
Q

Which scheduling algorithm accounts for the age of a process?

A

HRRN

24
Q

T/F In HRRN, each time a process is picked to execute, the ratio must be computed again for all processes

A

T

25
Q

T/F Multilevel feedback requires a time estimate

A

F

26
Q

What is a variation of multilevel feedback?

A

Assign longer quanta to lower queues

27
Q

What is the key to effective multiprogramming?

A

Scheduling

28
Q

What is the goal of scheduling?

A

Execute processes in such a way as to meet the system objectives, such as response time, throughput, and processes efficiency

OS Concepts (Ozbirn) (12 decks)

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