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BOT-MICS: Bounding time using analytics in mixed-criticality systems

Ranjbar, B ; Sharif University of Technology | 2021

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  1. Type of Document: Article
  2. DOI: 10.1109/TCAD.2021.3127867
  3. Publisher: Institute of Electrical and Electronics Engineers Inc , 2021
  4. Abstract:
  5. An increasing trend for reducing cost, space, and weight leads to modern embedded systems that execute multiple tasks with different criticality levels on a common hardware platform while guaranteeing a safe operation. In such Mixed-Criticality (MC) systems, multiple Worst-Case Execution Times (WCETs) are defined for each task, corresponding to system operation mode to improve the MC system’s timing behavior at run-time. Determining the appropriate WCETs for lower criticality modes is non-trivial. On the one hand, considering a very low WCET for tasks can improve the processor utilization by scheduling more tasks in that mode, on the other hand, using a larger WCET ensures that the mode switches (which causes by task overrunning) are minimized, thereby improving the quality-of-service for all tasks, albeit at the cost of processor utilization. Hitherto, no analytical solutions are proposed to determine WCETs in lower criticality modes. In this regard, we propose a scheme to determine WCETs by Chebyshev theorem, to make a trade-off between the number of scheduled tasks at design-time and the number of dropped low-criticality tasks at run-time as a result of frequent mode switches. To have a tight bound of execution times and mode switching probability, we also propose a distribution analytics-based scheme, in which the mode switching probability is obtained based on the cumulative distribution function. Our experimental results show that our scheme improves the utilization of state-of-the-art MC systems by up to 72.27%, while maintaining 24.28% mode switching probability in the worst-case scenario. Besides, the results of running embedded real-time benchmarks on a real platform show that the distribution-based scheme can improve the utilization by 7.30% while bounding the mode switching probability by 4.85% more, compared to the Chebyshev-based scheme. IEEE
  6. Keywords:
  7. Cost benefit analysis ; Criticality (nuclear fission) ; Distribution functions ; Economic and social effects ; Embedded systems ; Interactive computer systems ; Job analysis ; Quality control ; Quality of service ; Time switches ; Analyse ; Bad-case execution time’ ; Mixed criticalities ; Mode switching probability ; Mode-switching ; Optimisations ; Quality-of-service ; Real - Time system ; Resources utilizations ; Schedulability ; Switching probability ; Systems operation ; Task analysis ; Tight execution time bound ; Time bound ; Worst-case execution time ; Real time systems
  8. Source: IEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems ; 2021 ; 02780070 (ISSN)
  9. URL: https://ieeexplore.ieee.org/document/9612593