22 December 2008

Earliest Deadline First (EDF) Algorithm

  • It is an Optimal dynamic Priority Scheduling Algorithm
  • Priorities are assigned based on the absolute deadlines of the task, earlier the deadline, higher the priority.
  • It is also called as Deadline Monotonic Scheduling (DM).
  • If two tasks have the same deadline, then EDF randomly select  one to execute next.
  • The Schedulability condition for EDF is edf

where U is the processor Utilisation Factor and it never be greater than 1.

In practical, no processor will be utilised for more than 100%.