Betriebssysteme · Institut für Systemarchitektur · Fakultät Informatik · TU Dresden

13. 06. 2014

Using circular range for a more precise description of period compatibility for rate-monotonic schedulability tests

Dirk Müller

TU Chemnitz

For periodic task sets on a uniprocessor, the optimal fixed-priority scheduling algorithm is rate-monotonic scheduling (RMS). The shorter a task's period, the higher is its priority. For simply-periodic task sets, RMS achieves a utilization bound of 1. But this drops to the famous Liu/Layland bound of ca. 0.69 in the general case. The Burchard test calculates a refined utilization bound based on the period configuration. This test uses linear range of so-called S values for describing period compatibility. It will be shown how a change to circular range can ensure the natural requirement of scale invariance, give higher sensitivity, and -- as a side effect -- simplify the Burchard test formula.
25. Jun 2020
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