How do you have a hard realtime system when the amount of work needed to be done in a period of time is not deterministic? How can you even prove the bounds of the amount of work?
The way I understand it is a hard realtime system does not solve that problem but does ensure the process with too much work does not prevent any other process from meeting its obligations. In other words, the failure to meet demand is isolated & prevented from cascading into other tasks.
Of course, if the process that is overloaded is the process responsible for keeping the system from crashing into the Sun, this doesn't quite fix the problem.
