Deadlock Prevention

Simple really - DENY one of the four necessary conditions!

1. Make resources sharable (e.g spooling) no mutual exclusion
2. Processes MUST request ALL resources at the same time. Either all at start or release all before requesting more no hold and wait for :
   Poor resource utilisation and possible starvation
3. If process requests a resource which is unavailable - it must release all resources it currently holds - and try again later allow preemption - loss of work
4. Impose an ordering on resource types. Process requests resources in a pre-defined order no circular wait = this can be over restrictive

In general therefore, with prevention we get low device utilisation and reduced system throughput