Chap 9

Question 1

In a multiprogramming system multiple processes exist concurrently in main memory.

Answer 1

TRUE

Question 2

The key to multiprogramming is scheduling.

Answer 2

TRUE

Question 3

The medium-term scheduler is invoked whenever an event occurs that may lead to the blocking of the current process or that may provide an opportunity to preempt a currently running process in favor of another.

Answer 3

FALSE

Question 4

Scheduling affects the performance of the system because it determines which processes will wait and which will progress.

Answer 4

TRUE

Question 5

The main objective of long-term scheduling is to allocate processor time in such a way as to optimize one or more aspects of system behavior

Answer 5

FALSE

Question 6

In most interactive operating systems adequate response time is the critical requirement.

Answer 6

TRUE

Question 7

One problem with a pure priority scheduling scheme is that lower-priority processes may suffer starvation.

Answer 7

TRUE

Question 8

First-come-first-serve (FCFS) performs much better for short processes than long ones.

Answer 8

FALSE

Question 9

Round robin is particularly effective in a general-purpose time-sharing system or transaction processing system.

Answer 9

TRUE

Question 10

The objective of a fair-share scheduler is to monitor usage to give fewer resources to users who have had more than their fair share, and more to those who have had less than their fair share.

Answer 10

TRUE

Question 11

The traditional UNIX scheduler employs multilevel feedback user round robin within each of the priority queues.

Answer 11

TRUE

Question 12

First-come-first-serve (FCFS) is a simple scheduling policy that tends to favor I/O-bound processes over processor-bound processes.

Answer 12

FALSE

Question 13

In the Highest Response Ratio Next (HRRN) scheduling policy, longer jobs are favored because they yield a larger ratio from the smaller denominator in the equation.

Answer 13

FALSE

Question 14

A disadvantage of simulation is that results for a given run only apply to that particular collection of processes under that particular set of assumptions.

Answer 14

TRUE

Question 15

In fair share scheduling each user is assigned a weighting of some sort that defines that user’s share of system resources as a fraction of the total usage of those resources.

Answer 15

TRUE

Question 16

The decision as to which available process will be executed by the processor: _______________

Answer 16

short term scheduling

Question 17

The __________ determines which process, among ready processes, is selected next for execution.

Answer 17

selection function

Question 18

Which scheduling policy allows the OS to interrupt the currently running process and move it to the Ready state?

Answer 18

preemptive

Question 19

The __________ specifies the instants in time at which the selection function is exercised.

Answer 19

decision mode

Question 20

The traditional UNIX scheduler divides processes into fixed bands of priority levels, with the highest priority band being the _________.

Answer 20

swapper band

Question 21

This is a decision whether to add a new process to the set of processes that are currently active:

Answer 21

long term scheduling

Question 22

A risk with __________ is the possibility of starvation for longer processes, as long as there is a steady supply of shorter processes.

Answer 22

SPN

Question 23

The decision as to which process’ pending I/O request shall be handled by an available I/O device:

Answer 23

I/O scheduling

Question 24

In the case of the _________ policy, the scheduler always chooses the process that has the shortest expected remaining processing time.

Answer 24

SRT (Shortest Remaining Time)

Question 25

This is a decision on whether to add a process to those that are at least partially in the main memory and therefore available for execution.

Answer 25

medium-term scheduling

Question 26

Response time in an interactive system is an example of:

Answer 26

user-oriented criteria for short-term policies

Question 27

__________ considers the execution history of a related group of processes along with the individual execution history of each process in making scheduling decisions.

Answer 27

FSS

Question 28

The operating system must make ________ types of scheduling decisions with respect to the execution of processes.

Answer 28

3

Question 29

Typically, the swapping-in function for processes is based on the need to manage ___________.

Answer 29

degree of multiprogramming

Question 30

The strategy that schedules processes based on their group affiliation is generally referred to as ___________.

Answer 30

fair share scheduling

Question 31

The aim of ________ is to assign processes to be executed by the processor or processors over time, in a way that meets system objectives, such as response time, throughput, and processor efficiency.

Answer 31

processor scheduling

Question 32

The __________ scheduler determines which programs are admitted to the system for processing.

Answer 32

long term

Question 33

_________ is the elapsed time between the submission of a request until the response begins to appear as output.

Answer 33

response time

Question 34

The simplest scheduling policy is __________.

Answer 34

first come first served

Question 35

__________ scheduling is part of the swapping function.

Answer 35

medium term

Question 36

In terms of the queuing model, _________ is the total time that the item spends in the system (waiting time plus service time).

Answer 36

turnaround time

Question 37

Giving each process a slice of time before being preempted is a technique known as __________.

Answer 37

time slicing

Question 38

A common technique for predicting a future value on the basis of a time series of past values is __________.

Answer 38

exponential averaging

Question 39

The ___________ scheduler executes most frequently and makes the fine-grained decision of which process to execute next.

Answer 39

short term

Question 40

The _________ approach means that the operating system allocates the processor to a process and when the process blocks or is preempted, feeds it back into one of several priority queues.

Answer 40

multilevel feedback

Question 41

The need to know or estimate required processing times for each process, the starvation of longer processes, and the lack of preemption are all difficulties with the __________ scheduling technique.

Answer 41

Shortest Process Next (SPN)

Question 42

Response time and throughput are examples of __________ criteria for short-term scheduling.

Answer 42

performance-based

Question 43

_________ is a scheduling policy in which the process with the shortest expected processing time is select next, and if a shorter process becomes ready in the system, the currently running process is preempted.

Answer 43

Shortest Remaining Time (SRT)

Question 44

The traditional UNIX scheduler, such as those used in SVR3 and 4.3 BSD UNIX systems, divides processes into fixed ________ of priority levels.

Answer 44

bands

Question 45

A scheduling mechanism that requires no prior knowledge of process length yet can nevertheless favor shorter jobs, is known as the _________ scheduling mechanism.

Answer 45

feedback