Exact speedup factors for linear-time schedulability tests for fixed-priority preemptive and non-preemptive scheduling

详细信息    查看全文

• 作者：Georg von der Brü ; ggen^a ; Jian-Jia Chen^a ; ^{jian-jia.chen@cs.uni-dortmund.de" class="auth_mail" title="E-mail the corresponding author} ; Robert I. Davis^b ; ^c ; Wen-Hung Huang^a
• 关键词：Real-time systems ; Speedup factors ; Fixed-priority real-time scheduling ; Non-preemptive and preemptive scheduling ; Schedulability tests
• 刊名：Information Processing Letters
• 出版年：2017
• 出版时间：January 2017
• 年：2017
• 卷：117
• 期：Complete
• 页码：1-5
• 全文大小：266 K

文摘

In this paper, we investigate the quality of several linear-time schedulability tests for preemptive and non-preemptive fixed-priority scheduling of uniprocessor systems. The metric used to assess the quality of these tests is the resource augmentation bound commonly known as the processor speedup factor. The speedup factor of a schedulability test corresponds to the smallest factor by which the processing speed of a uniprocessor needs to be increased such that any task set that is feasible under an optimal preemptive (non-preemptive) work-conserving scheduling algorithm is guaranteed to be schedulable with preemptive (non-preemptive) fixed priority scheduling if this scheduling test is used, assuming an appropriate priority assignment. We show the surprising result that the exact speedup factors for Deadline Monotonic (DM) priority assignment combined with sufficient linear-time schedulability tests for implicit-, constrained-, and arbitrary-deadline task sets are the same as those obtained for optimal priority assignment policies combined with exact schedulability tests. Thus in terms of the speedup-factors required, there is no penalty in using DM priority assignment and simple linear schedulability tests.