Xenomai在不同域中的优先级问题

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最新推荐文章于 2021-05-14 12:26:29 发布

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本文通过两个实例解析了Xenomai实时操作系统中不同优先级线程的调度机制。详细介绍了当线程处于不同域（Xenomai域与Linux域）时，Xenomai调度器如何选择合适的线程进行调度。

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First example:
---------------------
Suppose that at a rescheduling we have the following thread in the ready 
queues
- High Priority -> Linux thread H
- Medium Priority -> Xenomai thread M in PRIMARY domain
- Low Priority -> Xenomai thread L in primary domain

Then, the Xenomai scheduler will select M, and M will be dispatched.

Second example:
--------------------------
- High Priority -> Linux thread H
- Medium Priority -> Xenomai thread M in SECONDARY domain
- Low Priority -> Xenomai thread L in primary domain

Then, the Xenomai scheduler will select M. but M is in secondary mode, 
which means the Linux kernel will be scheduled. The Linux scheduler 
knows H (it's a linux thread), M (it's in secondary mode), and maybe 
about L (if it has been created by UVMs). The Linux scheduler will 
choose H, and H will be scheduled.

比如例一，在Xenomai域中的低优先级的线程M(低于Linux域的线程H)会被调度。

例二，如果线程M进入Linux域后，这里比较关键，不是线程Ｌ被调度，而是在Linux域中的高优先级线程Ｈ被调度。

如果在Xenomai域中有优先级高于线程Ｍ的线程Ｚ，那么Ｚ则会被调度。

参考：

http://www.xenomai.org/pipermail/xenomai/2005-December/001881.html

http://www.xenomai.org/pipermail/xenomai/2005-December/001882.html