Chapter 4 - DSpace at Waseda University

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Appendix critical task and non-critical task. Moreover, according to whether CPU is conceded or not when high priority task arrives, it can be divided in to preemptive task and non-preemptive task. Common task concedes CPU to high priority task, which is preemptive task. However, when task is processing critical section, it cannot be prior occupied. Methods of giving priority to task are static priority method and dynamic priority method. Static priority is a method that never changes priority that was assigned from scheduler and dynamic priority means method that changes dynamically according to process that will be occurred. The dynamic priority method can be scheduled more effectively more than static priority. The dynamic priority algorithm mostly used in commercial real-time OS, such as VxWorks or PSOS, are fixed priority scheduling and Earliest Deadline First (EDF) method. Both of algorithms are preemptive scheduling method and they are algorithm that assumes single processor. Firstly, as shown in the name, fixed priority scheduling is a method that gives fixed priority to every task. It was a problem about how to grant fixed priority. In 1973, Liu and Laryland proposed algorithm called rate-monotonic scheduling. This method proposed to grant high priority to task with short period (premise: every task is periodic task and deadline of task is equal to period of task). Due to simplicity of rate-monotonic scheduling and its mathematical characteristic which makes it possible to schedule anytime Utilization Factor (UF) is under 0.67, it was often used for these few decades. EDF is an algorithm that grants higher priority to task that is shorter to deadline. For this reason, it is also called as deadline driven algorithm. This algorithm can be used to schedule not only periodic task but also all other tasks on single processor architecture. It was proved that it is most optimal mathematically. 86
A.4 CABI 87 Appendix CABI is the system which manages CPU resource in Linux. Linux does not restrict the resource consumption for their processes. For example, when malicious application programs are downloaded and executed, the programs may consume a large amount of the CPU capacity easily. For the multimedia applications, more fine grain and CPU reservation control is needed. These requirements such as CPU QoS are increasing even in the Embedded System area. To solve this problem, CABI (CPU Accounting and Blocking Interfaces, currently that change the name to Common resource Accounting and Blocking Interfaces) [50] [51] proposed, a general-purpose resource monitoring and restriction system that prevents the excessive use of the resource capacity of a process or a group of processes. The CABI implemented in the Linux kernel. CABI was designed by the consideration of the following three issues [51] � Simplicity CABI should be simple and generic to be used in a variety of OS services such as security enhancement, class-based accounting, overload monitoring, and processor reservation. � Accuracy CABI should monitor the CPU capacity of each process very accurately for making the execution of application more stable. A fine-grained timer is used to realize the accurate monitoring.
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Analyzing Real-Time Performance Pro
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to propose a solution for the probl
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2.5 Event Log …………………
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6. Conclusions and Future Work 6.1
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List of Figures 2.1 User-space vs.
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5.12: One of the reasons of HRTimer
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Chapter 1 functions or equipped wit
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Chapter 1 huge losses in cost. For
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Chapter 1 1.3 Contribution When dev
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Chapter 2 Background 2.1 Embedded S
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Chapter 2 memory and to manage syst
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Chapter 2 2.3 Embedded Linux An emb
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Chapter 2 � How often CPU accesse
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Chapter 2 2.6 Problem Analysis Figu
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Chapter 2 � To count time accurat
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Chapter 2 board. Its clock signal i
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Chapter 3 hardware such as SoC (Sys
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Chapter 3 free to check memory. How
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Chapter 3 Figure 3.3: Process viewe
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Chapter 3 In Figure 3.4, through Me
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Chapter 3 Figure 3.6: Event logging
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Chapter 4 execution times, and whol
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Page 102 and 103: Bibliography [1] L. Abeni, A. Goel,
Page 104 and 105: Bibliography [21] C. Yuan, N. Lao,
Page 106 and 107: Bibliography [38] Magdalena Balazin
Page 108 and 109: Bibliography [56] Balakrishnan, S.;
Page 110 and 111: Acknowledgements I would firstly li
Page 112 and 113: Publication List 種類別題名
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