A constant-approximate feasibility test for multiprocessor real-time scheduling

We devise the first constant-approximate feasibility test for sporadic multiprocessor real-time scheduling. We give an algorithm that, given a task system and ε > 0, correctly decides either that the task system can be scheduled using the earliest deadline first algorithm on m speed-(2 - 1/m + ε) machines, or that the system is infeasible for m speed-1 machines. The running time of the algorithm is polynomial in the size of the task system and 1/ε. We also provide an improved bound trading off speed for additional machines. Our analysis relies on a new concept for counting the workload of an interval, that might also turn useful for analyzing other types of task systems. © 2008 Springer-Verlag Berlin Heidelberg