Operating Systems Chapter 5

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Questions and Answers

What is a key characteristic of a multilevel queue scheduler?

It schedules processes based solely on their burst time.

It consists of multiple queues with specific scheduling algorithms. (correct)

It requires equal priority for all process types.

It has a single queue for all processes.

In a multilevel queue scheduling system, how are processes prioritized?

Based on a fixed time quantum for each queue.

Based on their arrival time.

With a round-robin approach across all queues.

By assigning separate queues for different priority processes. (correct)

What does a multilevel feedback queue allow that a regular multilevel queue does not?

A single priority level for all processes.

Processes to move between queues based on their behavior. (correct)

Improved throughput by eliminating context switching.

Fixed priority to all processes.

Which of the following is NOT a parameter that defines a multilevel queue scheduler?

Total processing power of the CPU. Signup and view all the answers

Which scheduling algorithm typically assigns processes to the highest-priority queue?

Priority scheduling. Signup and view all the answers

What is the main characteristic of a multilevel-feedback-queue scheduler regarding process management?

It allows processes to move between different queues based on their behavior. Signup and view all the answers

In a multilevel feedback queue system with three queues as defined, what happens to a process in Q0 if it does not finish within 8 milliseconds?

It is moved to Q1 for further processing. Signup and view all the answers

Which scheduling algorithm is used in Q2 of the multilevel-feedback-queue example?

First-Come, First-Served Signup and view all the answers

What determines when a process is upgraded in a multilevel-feedback-queue scheduler?

The process's behavior during its allocation. Signup and view all the answers

In the example of the multilevel-feedback queues, what is the time quantum allocated to a process in Q1?

16 milliseconds Signup and view all the answers

What type of scheduling method is utilized in Q0 of the multilevel-feedback-queue?

Round Robin Signup and view all the answers

How does aging function in a multilevel-feedback-queue scheduler?

It prevents processes from getting starved of CPU time over time. Signup and view all the answers

What is the effect on a process that completes its execution while in Q1?

It is removed from the system. Signup and view all the answers

What is the average waiting time for the processes P1, P2, P3, P4, and P5 using SRT?

4.5 Signup and view all the answers

What is the average turnaround time for the processes in Round Robin scheduling with quantum=2?

5.0 Signup and view all the answers

Which process finishes first in the SRT scheduling for the given processes?

P4 Signup and view all the answers

In Round Robin scheduling, what happens to a process if its burst time exceeds the quantum?

It is placed at the end of the queue. Signup and view all the answers

What is the impact of increasing the quantum in Round Robin scheduling?

Increases context switching overhead. Signup and view all the answers

What will be the total burst time for the processes P1 to P6 in non-preemptive priority scheduling?

18 Signup and view all the answers

For the provided processes using Nonpreemptive Priority Scheduling, which parameter determines the order of execution?

Priority value Signup and view all the answers

Study Notes

Chapter 5: CPU Scheduling

CPU scheduling is a key aspect of operating systems
Different scheduling algorithms have varying characteristics
Objectives include describing various CPU scheduling algorithms, assessing algorithms based on criteria, explaining multiprocessor/multicore scheduling issues, and describing real-time scheduling algorithms
The ready queue may consist of multiple queues
Multilevel queue schedulers are defined by parameters like the number of queues
Scheduling algorithms are used for each queue
Methods determine which queue a process enters when needed
Scheduling among queues is another factor
Priority scheduling can have different priority queues
Processes in higher priority queues are scheduled first
Multilevel queue prioritization is based on process type; real-time processes have highest priority, followed by system, interactive, and finally batch processes
A process can move between queues in a multilevel feedback queue
Number of queues, scheduling algorithms for each, how to upgrade/demote processes, and how to determine which queue a process enters when needed are key parameters for multilevel feedback queues
Aging can be implemented with multilevel feedback queues
Examples include RR (Round Robin) with varying time quanta, and FCFS (First Come First Served)

Question 1

FCFS is used for scheduling processes with arrival and burst times
Average waiting time and average turnaround time need to be calculated

Question 2

SJF (Shortest Job First) is used to schedule processes
Average waiting time and average turnaround time need to be calculated for the processes

Question 3

SRT (Shortest Remaining Time) is used to schedule processes
Average waiting time and average turnaround time need to be calculated

Question 4

RR (Round Robin) is used with a quantum of 2
Average waiting time and average turnaround time need to be calculated

Question 5

Nonpreemptive Priority Scheduling with different priorities is used to schedule processes
Average waiting time and average turnaround time need to be calculated

Question 6

Preemptive Priority Scheduling is used, and priorities and process times are listed
Average waiting time and average turnaround time need to be calculated

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Description

This quiz focuses on CPU scheduling within operating systems, covering various scheduling algorithms and their characteristics. You'll explore the ready queue, multilevel queue schedulers, and priority scheduling. Assess your understanding of real-time processes and queue management through this comprehensive review.

Operating Systems Chapter 5 - CPU Scheduling

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