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Investigation and Comparison of Software-based Fault-tolerant Techniques for Embedded OS

Mohammadi Makrani, Hossein | 2014

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 46154 (19)
  4. University: Sharif University of Technology
  5. Department: Computer Engineering
  6. Advisor(s): Miremadi, Ghassem
  7. Abstract:
  8. Embedded systems are employed as crucial control components in safety-critical and real-time areas such as medical devices, automobile, and aviation. To maintaining the dependability of such applications, several fault tolerance techniques have been proposed in the recent decades.In the recent years, the improvements in the performance of hardware devices lead to excessive attentions to software fault tolerance techniques. The software fault tolerance techniques can be implemented at the application code or operating system of an embedded system. Applying the fault tolerance techniques in operating system allow the designers to develop their application without worrying about the dependability of the whole system. Thus operating system approaches are more used in embedded systems. But, the implementation of fault tolerance techniques at the operating systems may have side effects, such as impact on real-time behavior of the embedded operating system or resource restriction. Thus many constraints (especially form performance point of view) should be considered in selecting a recovery technique.Considering the above discussion, the goal of Fault tolerance techniques which are presented in this study is to recover from the transient and permanent errors that take place inside the embedded operating system extensions. The common characteristic of these methods is that, they do not impose any modification on the base architecture of operating systems. Investigated recovery techniques are micro rebooting, recovery block, N-Version Programming(NVP), micro extension, and transactional extension. From the software point of view, Embedded Linux is selected as a target embedded operating system in this study. From the hardware point of view, the modified operating system is executed on an ARM Cortex A9 CPU which emulated by QEMU. It is noteworthy that the investigated techniques are generic and not architecture specific, so the results can be regenerated by any other configuration.To investigate the characteristics of each technique, a total of 5000 software errors are ignited. The simulation results show that the recovery time is decreased40.6 (ms) by one technique and the others increased it up to308.2 (ms). Also the performance overhead varies between 1.6% and 57.8% depending on the techniques
  9. Keywords:
  10. Recovery ; Efficiency ; Software Fault Tolerance ; Embedded Operating System

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