Partitioned multiprocessor scheduling has been widely accepted in academia and industry to statically assign and partition real-time tasks onto identical multiprocessor systems. This paper studies fixed-priority partitioned multiprocessor scheduling for sporadic real-time systems, in which deadline-monotonic scheduling is applied on each processor. Prior to this paper, the best known results are by Fisher, Baruah, and Baker with speedup factors 4−M2 and 3−M1
Nearby in the stack
for arbitrary-deadline and constrained-deadline sporadic real-time task systems, respectively, where
M
is the number of processors. We show that a greedy mapping strategy has a speedup factor
3−M1
when considering task systems with arbitrary deadlines. Such a factor holds for polynomial-time schedulability tests and exponential-time (exact) schedulability tests. Moreover, we also improve the speedup factor to
2.84306
when considering constrained-deadline task systems. We also provide tight examples when the fitting strategy in the mapping stage is arbitrary and
M
is sufficiently large. For both constrained- and arbitrary-deadline task systems, the analytical result surprisingly shows that using exact tests does not gain theoretical benefits (with respect to speedup factors) for an arbitrary fitting strategy.