Chap 6

Question 1

Deadlock is permanent because none of the events is ever triggered.

Answer 1

TRUE

Question 2

All deadlocks involve conflicting needs for resources by two or more processes.

Answer 2

TRUE

Question 3

Interrupts, signals, messages, and information in I/O buffers are all examples of reusable resources.

Answer 3

FALSE

Question 4

A useful tool in characterizing the allocation of resources to processes is the resource allocation graph.

Answer 4

TRUE

Question 5

For deadlock to occur, there must not only be a fatal region, but also a sequence of resource requests that has led into the fatal region.

Answer 5

TRUE

Question 6

An indirect method of deadlock prevention is to prevent the occurrence of a circular wait.

Answer 6

FALSE

Question 7

If access to a resource requires mutual exclusion then mutual exclusion must be supported by the OS.

Answer 7

TRUE

Question 8

The OS may preempt the second process and require it to release its resources if a process requests a resource that is currently held by another process.

Answer 8

TRUE

Question 9

Deadlock avoidance requires knowledge of future process resource requests.

Answer 9

TRUE

Question 10

An unsafe state is one in which there is at least one sequence of resource allocations to processes that does not result in a deadlock.

Answer 10

FALSE

Question 11

An atomic operation executes without interruption and without interference.

Answer 11

TRUE

Question 12

Deadlock avoidance is more restrictive than deadlock prevention.

Answer 12

FALSE

Question 13

The dining philosopher’s problem can be representative of problems dealing with the coordination of shared resources which may occur when an application includes concurrent threads of execution.

Answer 13

TRUE

Question 14

A signal is similar to a hardware interrupt but does not employ priorities.

Answer 14

TRUE

Question 15

A mutex is used to ensure that only one thread at a time can access the resource protected by the mutex.

Answer 15

TRUE

Question 16

A set of processes is _________ when each process in the set is blocked awaiting an event that can only be triggered by another blocked process in the set.

Answer 16

deadlocked

Question 17

Examples of _______ include processors, I/O channels, main and secondary memory, devices, and data structures such as files, databases, and semaphores.

Answer 17

reusable resources

Question 18

With _______ only one process may use a resource at a time and no process may access a resource unit that has been allocated to another process.

Answer 18

mutual exclusion

Question 19

A closed chain of processes exists, such that each process holds at least one resource needed by the next process in the chain is the condition of __________.

Answer 19

circular wait

Question 20

Once the processes have progressed into the _________, those processes will deadlock.

Answer 20

fatal region

Question 21

The strategy of deadlock __________ is to design a system in such a way that the possibility of deadlock is excluded.

Answer 21

prevention

Question 22

The __________ condition can be prevented by requiring that a process request all of its required resources at one time and blocking the process until all requests can be granted simultaneously.

Answer 22

hold and wait

Question 23

The fastest form of interprocess communication provided in UNIX is _____________.

Answer 23

shared memory

Question 24

The ____________ condition can be prevented by defining a linear ordering of resource types.

Answer 24

circular wait

Question 25

Requested resources are granted to processes whenever possible with ____________.

Answer 25

deadlock detection

Question 26

One of the most significant contributions of UNIX to the development of operating systems is the ___________.

Answer 26

pipe

Question 27

A _________ is a software mechanism that informs a process of the occurrence of asynchronous events.

Answer 27

signal

Question 28

The most common technique used for protecting a critical section in Linux is the ____________.

Answer 28

spinlock

Question 29

The __________ allows multiple threads to have simultaneous read-only access to an object protected by the lock.

Answer 29

readers/writer lock

Question 30

The ___________ is useful in sending a signal to a thread indicating that a particular event has occurred.

Answer 30

event object

Question 31

_________ can be defined as the permanent blocking of a set of processes that either compete for system resources or communicate with each other.

Answer 31

deadlock

Question 32

A ______ resource is one that can be safely used by only one process at a time and is not depleted by that use.

Answer 32

reusable

Question 33

A ________ resource is one that can be created and destroyed.

Answer 33

consumable

Question 34

The ________ is a directed graph that depicts a state of the system of resources and processes, with each process and each resource represented by a node.

Answer 34

resource allocation graph

Question 35

Three conditions of policy must be present for a deadlock to be possible: mutual exclusion, no preemption, and ________.

Answer 35

hold and wait

Question 36

Three general approaches exist for dealing with deadlock: prevent, avoid, and ______.

Answer 36

detect

Question 37

_________ allows the three necessary conditions but makes judicious choices to assure that the deadlock point is never reached.

Answer 37

avoidance

Question 38

The strategy of resource allocation denial is referred to as the ___________.

Answer 38

banker's algorithm

Question 39

The ________ of the system reflects the current allocation of resources to processes.

Answer 39

state

Question 40

________ strategies are very conservative and solve the problem of deadlock by limiting access to resources and by imposing restrictions on processes.

Answer 40

prevention

Question 41

Inspired by the concept of co-routines, a ________ is a circular buffer allowing two processes to communicate on the producer-consumer model.

Answer 41

pipe

Question 42

Two types of atomic operations are defined in Linux: integer operations and _______________.

Answer 42

bitmap operations

Question 43

Linux provides three types of semaphore facilities in the kernel: binary semaphores, counting semaphores, and ________.

Answer 43

reader-writer semaphores

Question 44

an executable entity within a process is a _________ object.

Answer 44

thread

Question 45

A program invocation, including the address space and resources required to run the program is a ______ object.

Answer 45

process