realtime:technical_basics
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| - | ======Technical basics: Important aspects for real time====== | ||
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| - | In oder to understand the functionality of an RTOS, you need to know | ||
| - | about both general and Linux specific mechanisms. | ||
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| - | ---- | ||
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| - | <WRAP half column> | ||
| - | ===== Linux specific preemption models ===== | ||
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| - | The mainline Linux kernel implements three different preemption models | ||
| - | for different fields of application like servers or desktop PCs. With | ||
| - | the PREEMPT_RT patch two additional preemption models are available. | ||
| - | The "Fully Preemptible Kernel" model is the one that turns Linux into | ||
| - | an RTOS. | ||
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| - | <WRAP rightalign>[[preemption_models|Read more about preemption models]]</WRAP> | ||
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| - | </WRAP> | ||
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| - | <WRAP half column> | ||
| - | ===== Scheduling - Policy and priority ===== | ||
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| - | The Linux kernel implements several real-time and non real-time | ||
| - | scheduling policies. Depending on the scheduling policy of the tasks | ||
| - | the scheduler decides which task is swapped out and which task is | ||
| - | processed next. | ||
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| - | <WRAP rightalign>[[sched_policy_prio|Read more about policy and priority]]</WRAP> | ||
| - | </WRAP> | ||
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| - | <WRAP half column> | ||
| - | ===== Scheduling - RT throttling ===== | ||
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| - | The RT throttling mechanism prevents a system to hang, if there is a | ||
| - | programming failure in a real-time application. This mechanism makes | ||
| - | it possible to stop such an application. The settings for RT | ||
| - | throttling are exported into the proc filesystem. | ||
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| - | <WRAP rightalign>[[sched_rt_throttling|Read more about RT throttling]]</WRAP> | ||
| - | </WRAP> | ||
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| - | <WRAP half column> | ||
| - | ===== Priority inversion - Priority inheritance ===== | ||
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| - | When a task with high priority is blocked by one with low priority | ||
| - | because of a mutually exclusive resource, a third task with priority | ||
| - | in between the others can run and finish before the task with the | ||
| - | highest priority resumes. This phenomenon is known as priority | ||
| - | inversion. It can be solved by priority inheritance. | ||
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| - | <WRAP rightalign>[[pi|Read more about priority inversion and inheritance]]</WRAP> | ||
| - | </WRAP> | ||
realtime/technical_basics.1466666259.txt.gz ยท Last modified: 2016/06/23 07:17 by anna-maria
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