Aperiodic servers


There are several textbook options for aperiodic tasks

The most easy to model: polling server
It behaves like a periodic task, which serves aperiodic activities
Definitely, it requires preemption and a real scheduler

The most easy to implement: background server
A process that uses all otherwise-unused CPU time
Again, it must be preempted by "real" jobs.
We might accept to special-case it (see above)