Efficient on-line schedulability tests for priority driven real-time systems

Abstract

Many computer systems, such as those for open system envir onmentsor multimedia servic es, ne edan efcient schedulability test for on-line admission control of new jobs. A lthough various p olynomial time schedulability tests have been propose d, they often fail to decide the schedulability of the system precisely when the system is heavily loade d. This paper presents e cient on-line sche dulability tests which are are shown to be more p r ecise and e cient than any existing polynomialtime schedulability tests. Moreover, our proposed t e s t s can be u s e d for the multiframe model where a task may have di erent computation times in di erent periods. We show the performance of the prop ose dsche dulability tests in several simulation experiments.

Comprehensive Comparison of Schedulability Tests for Uniprocessor Rate-Monotonic Scheduling

“…Because the number of roots could be much less than the number of tasks, and the size of its harmonic base, it is expected that the Root condition improves the acceptance ratio of the LL and HC conditions. This can be observed in Corollaries 2, 3 and 4 [16].…”

“…-Closed-form period-aware conditions: Period Oriented (PO) [14], Conditions based on Harmonic Chains [15][16][17] and CRMB [18].…”

“…Kuo et al [16] developed the Root condition and demonstrated that a task set can be feasibly scheduled as long as the utilization of the task set is no larger than…”

“…, where R is the number of roots in the task set. The concept of root is defined next [16]. In order to explain the concept of root, we will use the example described in the previous subsection:…”