Article: Improving computation efficiency of schedulability of transaction-based task model for distributed real-time embedded systems Journal: International Journal of Embedded Systems (IJES) 2016 Vol.8 No.4 pp.277 - 292 Abstract: In the transaction-based task model, the system consists of multiple end-to-end transactions; each transaction consists of multiple tasks, with or without explicit precedence constraints; each task has a release offset (with possible release jitter) relative to the transaction start time. The transaction-based task model is especially useful for schedulability analysis in distributed real-time systems. For schedulability analysis of this task model, some authors have developed an exact analysis algorithm with exponential time complexity and a pessimistic tractable analysis algorithm with polynomial time complexity. In this paper, we aim to improve the computation efficiency of the exact analysis algorithm to make it applicable to larger tasksets. We define the concept of dominance relationship between any pair of tasks in the same transaction with higher-priority than the task under analysis. If task τix dominates task τiy in the same transaction, then τiy can be omitted from the WCRT analysis equations to improve computation efficiency. We present effective techniques for determining dominance relationship between tasks. Performance evaluation shows that our technique can generate significant improvements in computation efficiency. Inderscience Publishers - linking academia, business and industry through research

Title: Improving computation efficiency of schedulability of transaction-based task model for distributed real-time embedded systems

Authors: Zonghua Gu; Hong Li; Haibin Cai

Addresses: College of Computer Science, Zhejiang University, Hangzhou 310027, China ' College of Computer Science, Zhejiang University, Hangzhou 310027, China ' Shanghai Key Laboratory of Trustworthy Computing, East China Normal University, Shanghai 200062, China

Abstract: In the transaction-based task model, the system consists of multiple end-to-end transactions; each transaction consists of multiple tasks, with or without explicit precedence constraints; each task has a release offset (with possible release jitter) relative to the transaction start time. The transaction-based task model is especially useful for schedulability analysis in distributed real-time systems. For schedulability analysis of this task model, some authors have developed an exact analysis algorithm with exponential time complexity and a pessimistic tractable analysis algorithm with polynomial time complexity. In this paper, we aim to improve the computation efficiency of the exact analysis algorithm to make it applicable to larger tasksets. We define the concept of dominance relationship between any pair of tasks in the same transaction with higher-priority than the task under analysis. If task τ_ix dominates task τ_iy in the same transaction, then τ_iy can be omitted from the WCRT analysis equations to improve computation efficiency. We present effective techniques for determining dominance relationship between tasks. Performance evaluation shows that our technique can generate significant improvements in computation efficiency.

Keywords: real-time scheduling; schedulability analysis; transaction-based task models; computational efficiency; distributed systems; real-time systems; embedded systems; dominance relationship.

DOI: 10.1504/IJES.2016.077772

International Journal of Embedded Systems, 2016 Vol.8 No.4, pp.277 - 292

Received: 26 May 2014
Accepted: 26 Jul 2014
Published online: 15 Jul 2016 *

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Title: Improving computation efficiency of schedulability of transaction-based task model for distributed real-time embedded systems

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