ABSTRACT
This chapter defines a schedulability test for either RMS or Earliest Deadline First (EDF) based on very simple calculations over the tasks period and execution time. It considers single-processor systems. The chapter shows how to compute the least upper bound Ulub of the processor utilization for Rate Monotonic (RM). It suggests that the utilization limit below which the task set is definitely schedulable will be greater in EDF scheduling compared to RM. The chapter presents two simple schedulability tests based on the processor utilization for RM and EDF scheduling algorithms. With respect to the sufficient schedulability test for the RM algorithm, the corresponding test for the EDF algorithm is conceptually simpler, and there is no "grey area" of uncertainty. The major advantage of such tests is simplicity: it is possible to execute at run-time a schedulability acceptance test whenever a new task is dynamically added in a running system.
