A real-time system must execute functionally correct computations in a timely manner. In order to guarantee that all tasks accepted in the system will meet their timing requirements, an admission control algorithm must be used to only accept tasks whose requirements can be satisfied. Rate-monotonic scheduling (RMS) is arguably the best known scheduling policy for periodic real-time tasks on uniprocessors. We propose a new and efficient admission control for rate-monotonic scheduling on a uniprocessor and analyze its performance. This admission control is then modified to provide an admission control mechanism for multiprocessor systems. Experimental results indicate that this new admission control for multiprocessor systems achieves a processor utilization of up to 96% for a large number of tasks and has a low computational complexity. The proposed admission control is also used to derive a new and better multiprocessor schedulability bound for RMS with provisions for periodic servers and for RMS with tolerance to transient faults.
['Sylvain Lauzac', 'Rami G. Melhem', 'Daniel Mossé']
An efficient RMS admission control and its application to multiprocessor scheduling