Chap 6 Flashcards
Deadlock is permanent because none of the events is ever triggered.
TRUE
All deadlocks involve conflicting needs for resources by two or more processes.
TRUE
Interrupts, signals, messages, and information in I/O buffers are all examples of reusable resources.
FALSE
A useful tool in characterizing the allocation of resources to processes is the resource allocation graph.
TRUE
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.
TRUE
An indirect method of deadlock prevention is to prevent the occurrence of a circular wait.
FALSE
If access to a resource requires mutual exclusion then mutual exclusion must be supported by the OS.
TRUE
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.
TRUE
Deadlock avoidance requires knowledge of future process resource requests.
TRUE
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.
FALSE
An atomic operation executes without interruption and without interference.
TRUE
Deadlock avoidance is more restrictive than deadlock prevention.
FALSE
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.
TRUE
A signal is similar to a hardware interrupt but does not employ priorities.
TRUE
A mutex is used to ensure that only one thread at a time can access the resource protected by the mutex.
TRUE
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.
deadlocked
Examples of _______ include processors, I/O channels, main and secondary memory, devices, and data structures such as files, databases, and semaphores.
reusable resources
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.
mutual exclusion
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 __________.
circular wait
Once the processes have progressed into the _________, those processes will deadlock.
fatal region
The strategy of deadlock __________ is to design a system in such a way that the possibility of deadlock is excluded.
prevention
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.
hold and wait
The fastest form of interprocess communication provided in UNIX is _____________.
shared memory
The ____________ condition can be prevented by defining a linear ordering of resource types.
circular wait
Requested resources are granted to processes whenever possible with ____________.
deadlock detection
One of the most significant contributions of UNIX to the development of operating systems is the ___________.
pipe
A _________ is a software mechanism that informs a process of the occurrence of asynchronous events.
signal
The most common technique used for protecting a critical section in Linux is the ____________.
spinlock
The __________ allows multiple threads to have simultaneous read-only access to an object protected by the lock.
readers/writer lock
The ___________ is useful in sending a signal to a thread indicating that a particular event has occurred.
event object
_________ can be defined as the permanent blocking of a set of processes that either compete for system resources or communicate with each other.
deadlock
A ______ resource is one that can be safely used by only one process at a time and is not depleted by that use.
reusable
A ________ resource is one that can be created and destroyed.
consumable
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.
resource allocation graph
Three conditions of policy must be present for a deadlock to be possible: mutual exclusion, no preemption, and ________.
hold and wait
Three general approaches exist for dealing with deadlock: prevent, avoid, and ______.
detect
_________ allows the three necessary conditions but makes judicious choices to assure that the deadlock point is never reached.
avoidance
The strategy of resource allocation denial is referred to as the ___________.
banker’s algorithm
The ________ of the system reflects the current allocation of resources to processes.
state
________ strategies are very conservative and solve the problem of deadlock by limiting access to resources and by imposing restrictions on processes.
prevention
Inspired by the concept of co-routines, a ________ is a circular buffer allowing two processes to communicate on the producer-consumer model.
pipe
Two types of atomic operations are defined in Linux: integer operations and _______________.
bitmap operations
Linux provides three types of semaphore facilities in the kernel: binary semaphores, counting semaphores, and ________.
reader-writer semaphores
an executable entity within a process is a _________ object.
thread
A program invocation, including the address space and resources required to run the program is a ______ object.
process
