next up previous
Next: Deadlock Avoidance Up: No Title Previous: Conditions for deadlock to

Deadlock Prevention

Simple really - DENY one of the four necessary conditions!

  1. Make resources sharable (e.g spooling) tex2html_wrap_inline238 no mutual exclusion
  2. Processes MUST request ALL resources at the same time. Either all at start or release all before requesting more tex2html_wrap_inline238 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 tex2html_wrap_inline238 allow preemption - loss of work
  4. Impose an ordering on resource types. Process requests resources in a pre-defined order tex2html_wrap_inline238 no circular wait = this can be over restrictive

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

Omer F Rana
Sat Feb 15 21:34:55 GMT 1997