Several schedulers may co-exist, assign fixed percentage of CPU-time to each scheduler.
Important schedulers :

  • Round-robin scheduler with priorities (the default scheduler)
  • Real-time scheduler (process needs to be assigned explicitly to this one) (typically FIFO)

Round Robin Scheduler with priorities

  • Maintain tree of processes order by runtime allocated so far
  • Picks next process as one with least runtime allocated so far
  • Inserts new process in ready queue at appropriate place in tree
  • Priorities handled by giving weights to run-times.