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Unformatted text preview: ation Need Available
P0 0 1 0
P1 3 0 2
P2 3 0 1
P3 2 1 1
P4 0 0 2
Executing safety algorithm shows that sequence < P1, P3,
P4, P0, P2> satisfies safety requirement.
Can request for (3,3,0) by P4 be granted?
Can request for (0,2,0) by P0 be granted?
Can Deadlock Detection Allow system to enter deadlock state
Allow Detection algorithm Recovery scheme Deadlocks Single Instance of Each Resource
Type Maintain wait-for graph
Maintain wait-for Nodes are processes.
Pi → Pj if Pi is waiting for Pj.
is Deadlocks Periodically invoke an algorithm that searches for a
cycle in the graph. If there is a cycle, there exists a
An algorithm to detect a cycle in a graph requires an
order of n2 operations, where n is the number of
vertices in the graph.
vertices Resource-Allocation Graph and
Wait-for Resource-Allocation Graph Corresponding wait-for graph Deadlocks Several Instances of a Resource
Type Available: A vector of length m indicates the number of
available resources of each type.
available Allocation: An...
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- Fall '13