Deadlock Summary

• Two main strategies : Prevention/Avoidance or Allow to occur and then recover
• Different strategies for different resources
• Internal Resources : Internal data structures (like PCBs (Kernel)), Prevention by resource ordering
• Main Memory : Memory used by a job, Prevention by preemption as requesting job can be swapped out and release memory it was holding
• Job Resources : Dedicated devices such as tape drives, disks. Avoidance since information needed about resource requirements can be known in advance
• Swap Space : Disk Space for paging etc. Avoidance by pre-allocation of maximum requirements, which are usually known in advance
• File Space : Operator recovery by selectively deleting files - temporary file, archived ones etc