OS quiz 3

The __________ class is intended for application that will only consume processor time when no other threads are ready to execute. A) idle user B) time-sharing C) bottom-half kernel D) real-time

idle user

A thread is considered to be _________ if the ratio of its voluntary sleep time versus its runtime is below a certain threshold.

interactive

Processes at _________ priority levels are guaranteed to be selected to run before any time-sharing process but must defer to real-time processes. A) kernel B) time-shared C) real time D) load sharing

kernel

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

long term

This is a decision whether to add a new process to the set of processes that are currently active: A) short-term scheduling B) long-term scheduling C) medium-term scheduling D) I/O scheduling

long-term scheduling

A disadvantage of static assignment is that one processor can be idle, with an empty queue, while another processor has a backlog.

true

A loosely coupled or distributed multiprocessor consists of a collection of relatively autonomous systems, with each processor having its own main memory and I/O channels.

true

A typical use of independent parallelism is in a time-sharing system.

true

Linux provided a real-time scheduling capability coupled with a scheduler for non-real-time processes that made use of the traditional UNIX scheduling algorithm.

true

One of the more promising methods of resolving multitask scheduling conflicts for periodic tasks is rate monotonic scheduling.

true

One useful measure of the ability of an operating system to function deterministically is the maximum delay from the arrival of a high-priority device interrupt to when servicing begins.

true

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

turnaround time

In the case of the __________ policy, the scheduler always chooses the process that has the shortest expected remaining processing time. A) SRT B) FCFS C) SPN D) HRRN

SRT

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

True

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

True

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

True

Static table-driven scheduling is applicable to tasks that are periodic.

True

The key to multiprogramming is scheduling.

True

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.

True

The operating system, and in particular the scheduler, is perhaps the most important component of a real-time system.

True

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

True

A __________ is one that must meet its deadline, otherwise it will cause unacceptable damage or a fatal error to the system. A) periodic task B) soft real-time task C) hard real-time task D) aperiodic task

hard real-time task

__________ occurs when circumstances within the system force a higher-priority task to wait for a lower-priority task.

Priority inversion

__________ is the time required to execute the task to completion. A) Processing time B) Priority C) Resource requirements D) Ready time

Processing time

•Processor utilization equation

Processor utilization p : tr/ts = 1/1-p turn around time / service time = 1/1-p

The simplest scheduling policy is __________ .

FCFS

__________ considers the execution history of a related group of processes along with the individual execution history of each process in making scheduling decisions. A) TAT B) HRRN C) FSS D) FCFS

FSS

The strategy that schedules processes based on their group affiliation is generally referred to as _________ . A) shortest process next B) fair share scheduling C) queuing analysis D) simulation modeling

Fair Share Scheduling

Because of the potential disadvantages, load sharing is not one of the commonly used schemes in current multiprocessors.

False

FCFS performs much better for short processes than long ones.

False

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

False

In most traditional multiprocessor systems processes are dedicated to processors.

False

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

False

Real-time tasks are not handled any differently than non-real-time tasks in the priority queues.

False

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.

False

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.

False

The decision as to which process' pending I/O request shall be handled by an available I/O device: A) long-term scheduling B) short-term scheduling C) I/O scheduling D) medium-term scheduling

I/O scheduling

Processes at _________ priority levels are guaranteed to be selected to run before any kernel or time-sharing process.

Real time

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.

Shortest Process Next (SPN)

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

Shortest Remaining Time (SRT)

__________ perform static analysis of feasible schedules of dispatching with the result of the analysis being a schedule that determines, at run time, when a task must begin execution. A) Static priority-driven preemptive approaches B) Static table-driven approaches C) Dynamic planning-based approaches D) Dynamic best effort approaches

Static table-driven approaches

The operating system must make _________ types of scheduling decisions with respect to the execution of processes. A) six B) four C) five D) three

Three

__________ is the lowest-priority process, intended for user applications other than real-time applications. A) Kernel B) Variable priority C) Real time D) Time-shared

Time-shared

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.

True

An application can be implemented as a set of threads, which cooperate and execute concurrently in the same address space.

True

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

True

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.

True

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

True

In the real-time-priority class, all threads have a fixed priority that never changes and all of the active threads at a given priority level are in a round-robin queue.

True

An _________ has a deadline by which it must finish or start, or it may have a constraint on both start and finish time.

aperiodic task

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

bands

The __________ specifies the instants in time at which the selection function is exercised. A) decision mode B) medium-term scheduling C) ready state D) TAT

decision mode

The _________ approach is the opposite of the load-sharing approach and provides implicit scheduling defined by the assignment of threads to processors.

dedicated processor assignment

An operating system is __________ to the extent that it performs operations at fixed, predetermined times or within predetermined time intervals.

deterministic

No feasibility analysis is performed with __________ approache, and the system tries to meet all deadlines and aborts any started process whose deadline is missed.

dynamic best effort

Linux uses _________ , in which threads are moved for a queue for one processor to a queue for another processor.

dynamic load balancing

With the __________ approach the number of threads in a process can be altered during the course of execution. A) dynamic scheduling B) load sharing C) gang scheduling D) dedicated processor assignment

dynamic scheduling

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

exponential averaging

_________ is a characteristic that refers to the ability of a system to fail in such a way s to preserve as much capability and data as possible.

fail-soft operation

User control is generally much broader in an ordinary operating system than in a real-time operating system.

false

With independent parallelism there is an explicit synchronization among processes.

false

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

feedback

An example of __________ is an I/O processor. A) loosely coupled or distributed multiprocessor B) tightly coupled multiprocessor C) cluster multiprocessing D) functionally specialized processors

functionally specialized processors

The __________ approach is a set of related threads scheduled to run on a set of processors at the same time, on a one-to-one basis. A) dynamic scheduling B) load sharing C) gang scheduling D) dedicated processor assignment

gang scheduling

__________ is useful for medium-grained to fine-grained parallel applications whose performance severely degrades when any part of the application is not running while other parts are ready to run.

gang scheduling

A good way of characterizing multiprocessors and placing them in context with other architectures is to consider the synchronization __________ , or frequency of synchronization, between processes in a system.

granularity

Typically, there will need to be rather a high degree of coordination and interaction among the threads of an application, leading to a __________ level of synchronization. A) independent grain B) medium grain C) course grain D) fine grain

medium grain

__________ scheduling is part of the swapping function.

medium term

This is a decision whether to add a process to those that are at least partially in main memory and therefore available for execution: A) long-term scheduling B) I/O scheduling C) short-term scheduling D) medium-term scheduling

medium-term scheduling

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.

multilevel feedback

In a __________ architecture, the kernel can execute on any processor, and each processor does self-scheduling from the pool of available processes.

peer

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

performance related

Which of the following scheduling policies allow the O/S to interrupt the currently running process and move it to the Ready state? A) FIFO B) FCFS C) non-preemptive D) preemptive

preemptive

In the __________ approach, a priority is associated with each resource. A) priority ceiling B) unbounded priority inversion C) priority inversion D) priority inheritance

priority ceiling

The basic idea of _________ is that a lower-priority task inherits the priority of any higher-priority task pending on a resource they share. A) priority ceiling B) priority inversion C) unbounded priority inversion D) priority inheritance

priority inheritance

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.

processor scheduling

For __________ scheduling, the highest-priority task is the one with the shortest period, the second highest-priority task is the one with the second shortest period, and so on.

rate monotonic

__________ is the time at which task becomes ready for execution.

ready time

__________ computing is defined as that type of computing in which the correctness of the system depends not only on the logical result of the computation but also on the time at which the results are produced.

real-time

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

response time

The _________ determines which process, among ready processes, is selected next for execution. A) decision mode B) selection function C) TAT D) long-term scheduler

selection function

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

short term

The decision as to which available process will be executed by the processor: A) long-term scheduling B) I/O scheduling C) medium-term scheduling D) short-term scheduling

short-term scheduling

A _________ has an associated deadline that is desirable but not mandatory. A) hard real-time task B) periodic task C) soft real-time task D) a periodic task

soft real-time task

A risk with _________ is the possibility of starvation for longer processes, as long as there is a steady supply of shorter processes. A) SRT B) SPN C) FIFO D) FCFS

spn

The traditional UNIX scheduler divides processes into fixed bands of priority levels, with the highest priority band being the _________ . A) user process band B) swapper band C) file manipulation band D) utilization band

swapper band

Typically, the swapping-in function for processes is based on the need to manage __________ . A) the degree of multiprogramming B) I/O requirements C) process priorities D) virtual memory

the degree of multiprogramming

The multiprocessor system which consists of a set or processors that share a common main memory and are under the integrated control of an operating system is a _________ . A) tightly coupled multiprocessor B) cluster C) loosely coupled or distributed multiprocessor D) functionally specialized processors

tightly coupled multiprocessor

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

time slicing

Response time in an interactive system is an example of: A) user-oriented criteria for long-term scheduling policies B) system-oriented criteria for short-term scheduling policies C) system-oriented criteria for long-term scheduling policies D) user-oriented criteria for short-term scheduling policies

user-oriented criteria for short-term scheduling policies

With coarse and __________ grained parallelism, there is synchronization among processes, but at a very gross level. A) medium B) fine C) independent D) very course

very course