Deadline scheduling in fault tolerant real time systems

Deadline scheduling means that the task with the earliest required response time is processed (earliest deadline first). In many points this kind of scheduling is superior to fixed priority scheduling. This work investigates the applicability of dynamic deadline scheduling in fault tolerant multicomputer systems with active redundancy and asynchronous scheduling. Tasks are preemptive and are subject to precedence constraints. It is shown that the additional computation resources necessary for fault situations can be reduced by relating the error detection timer to the deadline. If however the usual methods of deadline scheduling are applied deadlines can be missed. A new technique of deadline scheduling meeting all requirements for fault tolerant systems is proposed.