Operating Systems Chapter 5 Process Deadlocks

अब Quizwiz के साथ अपने होमवर्क और परीक्षाओं को एस करें!

Restricted Banker's Algorithm

If process p requests

process vertex

corresponds to a process and is represented by a circle.

Banker's algorithm approach

each process must first declare the max number of resources needed when the process is created.

Deadlock prevention or avoidance

ensures that the system never becomes deadlocked

solid edge

from a process vertex represents a request by this process to use on instance of the resource. From a resource vertex to a process vertex represents an assignment (or allocation) of an instance of this resource to the process.

segmented edge

from a process vertex to a resource vertex represents a future request by this process to use on instance of the resource. Also known as "claim edge"

Resource Allocation Graph

is a directed graph with two types of vertices and several types of edges. Absence of a cycle in the graph implies there is no deadlock

Deadlock

is a situation where two or more processes are waiting indefinitely for an event that can be caused only by one of the waiting processes.

Deadlock prevention

-Make all resource sharable (not possible in general) - Do not allow a process holding some resources to request and wait for other resources (disallows hold and wait condition for a deadlock to exist). First way to Implement this by requiring each process to request all needed resources at the beginning. Second way is to require each process to request resources only when it has none. -Allow preemption: When requesting a resource, a process must give the resources that its holding and request them again later -Linearly order the resources to prevent a circular wait.

Conditions for deadlock

-Non-sharable resources -No preemption (resources are released voluntarily by processes) -Circular waiting: process 0 waiting for recourse held by process 1, process 1 waiting for resource held by process 2,..., process n waiting for recourse held by process 0.

Deadlock Avoidance

Banker's algorithm approach

Deadlock detection or recovery

allows deadlocks to occur while running a detection algorithm regular or on-demand and then recovers from the detached deadlock

resource vertex

represented graphically by a rectangle, for each resource type has dots in it each corresponding to one resource instance of this type.


संबंधित स्टडी सेट्स

Chapter Exam 1- Insurance Life Policies

View Set

Supply Chain Management Principles Learning Block 2 - Practice Questions

View Set

Info Sec Final (from quizzes) FINISH

View Set

BAS 282: Marketing Services: Homework

View Set