Deck 10: Multiprocessor and Real-Time Scheduling

Question 1

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

Answer 1

D

Question 2

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.

Answer 2

True

Question 3

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

Answer 3

C

Question 4

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.

Question 5

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

Question 6

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.

Question 7

With independent parallelism there is an explicit synchronization among processes.

Question 8

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

Question 9

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

Question 10

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

Question 11

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

Question 12

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

Question 13

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

Question 14

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

Question 15

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

Question 16

In most traditional multiprocessor systems processes are dedicated to processors.

Question 17

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.

Question 18

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

Question 19

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

Question 20

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

Question 21

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

Question 22

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

Question 23

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.

Question 24

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

Question 25

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

Question 26

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

Question 27

__________ is the time required to execute the task to completion.

A) Processing time
B) Priority
C) Resource requirements
D) Ready time

Question 28

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

Question 29

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

Question 30

_________ 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.

Question 31

__________ 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

Question 32

__________ 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

Question 33

In the __________ approach, a priority is associated with each resource.

A) priority ceiling
B) unbounded priority inversion
C) priority inversion
D) priority inheritance

Question 34

__________ 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.

Question 35

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

Question 36

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

Question 37

__________ 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.

Question 38

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

Question 39

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

Question 40

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) aperiodic task

Question 41

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

Question 42

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

Question 43

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

Question 44

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.

Question 45

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