14. Basic Resource Scheduling

Question 1

Stateless Resource

Answer 1

• The amount of time to service a given request is independent from the history of the requests that have been served before

Question 2

Preemptive Resource

Answer 2

• A resource that can be temporarily interrupted to serve a different request

Question 3

Scheduling Overhead

Answer 3

• Any extra computation done while scheduling

Question 4

Processor-Bound Applications

Answer 4

• Applications with relatively long jobs and brief interactions with I/O devices

Question 5

I/O-Bound Applications

Answer 5

• Applications with short jobs and relatively long intervals of I/O waiting time

Question 6

Job

Answer 6

• An interval of execution that can be entirely conducted on the processor

Question 7

Task

Answer 7

• A sequence of jobs

Question 8

Scheduler Invocation

Answer 8

• Describes when the scheduler is invoked

Question 9

Scheduling Policy

Answer 9

• Describes the function according to which a job is selected to run

Question 10

Response Time (Scheduling)

Answer 10

• Process-centric
• The time between job release and completion

Question 11

Fairness (Scheduling)

Answer 11

• Process-centric
• The difference between the quality of service provided to different classes of jobs

Question 12

Utilization (Scheduling)

Answer 12

• System-centric
• The utilization of the resource with the considered scheduler

Question 13

Throughput (Scheduling)

Answer 13

• System-centric
• The rate at which requests are completed

Question 14

Complexity (Scheduling)

Answer 14

• System-centric
• The difficulty of correctly implementing and analyzing a scheduling algorithm

Question 15

First Come First Served (FCFS); First In First Out (FIFO)

Answer 15

• Invocation: once the currently running job has been completed (non-preemptive)
• Policy: select the job that has been waiting the longest in the queue

Question 16

Limitation of Any Non-Preemptive Scheduler

Answer 16

• Once a long job is given control of the processor, all the other jobs need to wait a long time before having the chance to execute

Question 17

Round-Robin Scheduler

Answer 17

• Invocation: at the expiration of a fixed time interval q (quantum) or if the currently running request completes (preemptive)
• Policy: selects the job waiting the longest since the time time it was processed in the quantum

Question 18

Slowdown (Scheduling)

Answer 18

• Response_time / requested_time

Question 19

When is the schedule produced by RR the same as the one produced by FIFO?

Answer 19

• When q is greater than or equal to the longest job in the system

Question 20

When is RR not fair?

Answer 20

• For I/O-bound tasks