Einführung

Real Time Scheduling Algorithms → Rate Montonic(RM)

Rate Montonic (RM) scheduling from Liu und Layland (1973) is probably the most well-known scheduling algorithm for independent periodic tasks. Rate monotonic scheduling is based on the following assumption:

The right hand side is about 0.7 for large n:

Equation 1:

Equation 1 requires that some of the computing power of the processor is not used in order to make sure that all requests are honored in time. If the above six RM-assumptions are met, all deadlines will be met.

RM scheduling is a preemptive scheduling policy with fixed priorities. The priority of tasks is a monotonically decreasing function of their period. In other words, tasks with a short period will get a high priority and tasks with a long period will be assigned a low priority. During the scheduling the tasks will be executed according to their priorities. That means, the currently executed task will be interrupted, if its period is longer than the period of a new arriving task.

 
Introduction > Real Time Scheduling Algorithms > Rate Montonic(RM)

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