A system is set forth that includes a processor, one or more memory storage units, and software code stored in the one or more memory storage units. The software code is executable by the processor to generate a plurality of adaptive partitions that are each associated with one or more process threads. Each of the plurality of adaptive partitions has a corresponding processor time budget. One or more of the process threads are designated as critical threads. Each adaptive partition associated with a critical thread is assigned a corresponding critical time budget. The software code also includes a scheduling system that is executable by the processor for selectively allocating the processor to run the process threads based, at least in part, on the processor time budgets of the respective adaptive partitions. The scheduling system may allocate the processor to run a critical thread based on the available critical time budget of the associated adaptive partition even when the processor time budget of the associated adaptive partition has been exhausted. In one example, the scheduling system functions so that it only bills the critical time budget of an adaptive partition for time used to run an associated critical thread when the processor is overloaded and the critical time budget for the adaptive partition is concurrently exhausted. Methods of implementing such a system are also set forth.