Adaptive partition scheduler


Adaptive partition schedulers are a relatively new type of partition scheduler, which in turn is a kind of scheduling algorithm, pioneered with the most recent version of the QNX operating system. Adaptive partitioning, or AP, allows the real-time system designer to request that a percentage of processing resources be reserved for a particular partition. The operating system's priority-driven pre-emptive scheduler will behave in the same way that a non-AP system would until the system is overloaded. During overload, the AP scheduler enforces hard limits on total run-time for the subsystems within a partition, as dictated by the allocated percentage of processor bandwidth for the particular partition.
If the system is not overloaded, a partition that is allocated 10% of the processor bandwidth, can, in fact, use more than 10%, as it will borrow from the spare budget of other partitions. This is very useful for the non real-time subsystems that experience variable load, since these subsystems can make use of spare budget from hard real-time partitions in order to make more forward progress than they would in a fixed partition scheduler such as , but without impacting the hard real-time subsystems' deadlines.
QNX Neutrino 6.3.2 and newer versions have this feature.