Silberschatz - Operating System Concepts 9th-cap7

Silberschatz - Operating System Concepts 9th-cap7

1. Deadlocks

   • Normal utilization resource sequence
     • 1.Request
     • 2.Use
     • 3.Release
   • Characterization
     • Mutual exclusion
     • Hold and wait
     • No preemption
     • Circular wait
     • graphically described:
       • Resource-allocation graph
   • Methods for handling
     • prevention
       • mutual exclusion
       • hold and wait
       • no preemption
       • circular wait
     • avoidance
       • safe state
       • resource-allocation graph algoritm
       • Banker's Algoritm
         • safety algoritm
         • Resource-Request algorithm
   • Detection
     • Single instance of each resource type
       • wait-for graph
     • multiple instance of each resource type
       • available structure
       • allocation structure
       • request structure
     • Detection-algorithm
   • Recovery
     • Process termination
       • Abort all deadlocked processes
       • Abort one process at a time until deadlock cycle is eliminated
     • Resource preemption
       • select a victim
       • rollback
       • starvation