Semi-Slack Scheduling Arbitrary Activation Patterns in Mixed-Criticality Systems

This paper proposes a semi-slack scheduling framework for mixed-criticality systems with arbitrary task activation patterns. In particular, based on the schedulability test of arbitrary task activation model, we present a tight slack-reclaim scheme that can adaptively make use of system slack to improve the quality of service to low critical tasks. This scheme works at the moment that low critical tasks are supposed to be degraded by the offline schedulability test, while at other moments the system is scheduled by the earliest deadline first with virtual deadlines. The semi-slack scheduling scheme is first discussed in uniprocessor and later extended to multiprocessor. Extensive simulation results demonstrate that compared with some state-of-the-art scheduling approaches, the proposed semi-slack scheduling scheme efficiently reduces deadline misses of low critical tasks without jeopardizing the guarantee to critical tasks.