Efficient feasibility analysis for real-time systems with EDF scheduling

This paper presents new fast exact feasibility tests for uniprocessor real-time systems using preemptive EDF (earliest deadline first) scheduling. Task sets which are accepted by previously described sufficient tests are evaluated in nearly the same time as with the old tests by the new algorithms. Many task sets are not accepted by the earlier tests despite them being feasible. These task sets are evaluated by the new algorithms a lot faster than with known exact feasibility tests. Therefore, it is possible to use them for many applications for which only sufficient test are suitable. Additionally this paper shows that the best previous known sufficient test, the best known feasibility bound and the best known approximation algorithm can be derived from these new tests. As a result, this leads to an integrated schedulability theory for EDF.