Deadline-monotonic priority assignment is a priority assignment policy used with fixed-priority pre-emptive scheduling.
With deadline-monotonic priority assignment, tasks are assigned priorities according to their deadlines. The task with the shortest deadline is assigned the highest priority. This priority assignment policy is optimal for a set of periodic or sporadic tasks which comply with the following system model:
If restriction 7 is lifted, then "deadline minus jitter" monotonic priority assignment is optimal.
If restriction 1 is lifted, allowing deadlines greater than periods, then Audsley's optimal priority assignment algorithm may be used to find the optimal priority assignment.
Deadline monotonic priority assignment is not optimal for fixed priority non-pre-emptive scheduling.
A fixed priority assignment policy P is referred to as optimal if no task set exists which is schedulable using a different priority assignment policy which is not also schedulable using priority assignment policy P. Or in other words: Deadline-monotonic priority assignment (DMPA) policy is optimal if any process set, Q, that is schedulable by priority scheme W, is also schedulable by DMPA