A Safety Scheduling Mechanism of High Assurance Real Time Operating System

To buildup the safety of real time operating system, after status quo of existing scheduling mechanism analyzed, brought forward a kind of novel safety scheduling mechanism based on Maximum Criticality First (MCF). MCF is a hybrid priorities real time scheduling algorithm which consisting of three parts, the first two parts are the assignment of the importance and user priority, which is done statically, the second part is the assignment of the dynamic priority based on minimum laxity first scheduling algorithm. MCF synthesizes the strongpoint of the fixed priority scheduling algorithm and the dynamic priority scheduling algorithm. By this way, MCF not only takes full advantage of resources such as CPU, also make critical task not suffer from other non critical tasks at transient overload. The safety of real time operating system is improved with MCF.