Chapter 6

Question 1

What is a Short-Term scheduler?

Answer 1

It selects from among the processes in ready queue, and allocates the CPU to one of them.

Question 2

When CPU scheduling may take place?

Answer 2

1. Switches from running to waiting state
2. Switches from running to ready state.
3. Switches from waiting to ready
4. Terminates

Question 3

Scheduling under 1 and 4 is?

Answer 3

Nonpreemtive

Question 4

When is scheduling preemptive?

Answer 4

When scheduling is not 1 and 4

Question 5

What is a Dispatcher?

Answer 5

Dispatches module gives control of the CPU to the process selected by the short-term scheduler

Question 6

What involves Dispatcher?

Answer 6

Switching context
Switching to user mode
Jumping to the proper location in the user program to restart that program

Question 7

What is Dispatch Latency?

Answer 7

Time it takes for the dispatcher to stop one process and start another one

Question 8

List Scheduling Criteria?

Answer 8

CPU Utilization
Throughput
Turnaround time
Waiting time
Response time

Question 9

What is CPU Utilization?

Answer 9

Keep the CPU as busy as possible

Question 10

What is Throughput?

Answer 10

of processes that complete their execution per time unit

Question 11

What is Turnaround Time?

Answer 11

Amount of time to execute a particular process

Question 12

What is Waiting Time?

Answer 12

Amount of time a process has been waiting in the ready queue

Question 13

What is Response Time?

Answer 13

Amount of time it takes from when a request was submitted until the first response is produced, not output.

Question 14

Scheduling Algorithm Optimization Criteria?

Answer 14

Max CPU utilization
Max throughput
Min turnaround time
Min waiting time
Min response time

Question 15

What is FCFS Scheduling?

Answer 15

First-Come, First Served

Question 16

What is Convoy effect?

Answer 16

Short process behind long process

Question 17

What is SJF?

Answer 17

Shortest Job First Scheduling

Associate with each process the length of its next CPU burst

Question 18

Priority Scheduling?

Answer 18

A priority number is associated with each process
The cpu is allocated to the process with the highest priority
Smallest int = highest priority

Question 19

What is the problem in Priority Scheduling?

Answer 19

Starvation - low priority processes may never execute

Question 20

What is Solution in priority scheduling?

Answer 20

Aging - as time progresses increase the priority of the process

Question 21

What is Round Robin?

Answer 21

Each process gets a small unit of CPU time. After the time has elapsed, the process is preempted and added to the end of the ready queue.

Question 22

Multilevel Queue?

Answer 22

Ready queue is partitioned into seperate queues

Question 23

Queues in Multilevel?

Answer 23

foreground (interactive) -RR

background (batch) - FCFS

Question 24

Highest to Lowest Priority?

Answer 24

System Processes
Interactive Processes
Interactive Processes
Interactive Editing Processes
Batch Processes
Student Processes

Question 25

Multilevel-feedback-queue scheduler is defined by?

Answer 25

Number of queues
Scheduling algorithms for each queue
Method for Upgrade process
Method for Demote process
Method used to determine which queue a process will enter when that process needs a service.

Question 26

Real - Time Scheduling?

Answer 26

Hard real-time systems

Soft real-time computing

Question 27

Hard real-time systems?

Answer 27

Required to complete a critical task within a guaranteed amount of time

Question 28

Soft real-time computing?

Answer 28

Requires that critical processes receive priority over less fortunate ones

Question 29

What is Analytic Evaluation?

Answer 29

Takes a particular predetermined workload and defines the performance of each algorithm for that workload.