Linux内核默认工作者线程的处理

最新推荐文章于 2024-07-08 09:32:06 发布

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最新推荐文章于 2024-07-08 09:32:06 发布

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本文详细解析了Linux内核中工作队列机制的核心组件worker_thread()函数。该函数通过无限循环实现任务的状态标记、等待队列管理和调度等功能，确保延迟工作能够被正确执行。

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摘至：http://www.makelinux.net/books/lkd2/ch07lev1sec4

Let's look at the heart of worker_thread(), simplified:

for (;;) {
        set_task_state(current, TASK_INTERRUPTIBLE);
        add_wait_queue(&cwq->more_work, &wait);

        if (list_empty(&cwq->worklist))
                schedule();
        else
                set_task_state(current, TASK_RUNNING);
        remove_wait_queue(&cwq->more_work, &wait);

        if (!list_empty(&cwq->worklist))
                run_workqueue(cwq);
}

This function performs the following functions, in an infinite loop:

The thread marks itself sleeping (the task's state is set to TASK_INTERRUPTIBLE) and adds itself to a wait queue.
If the linked list of work is empty, the thread calls schedule() and goes to sleep.
If the list is not empty, the thread does not go to sleep. Instead, it marks itself TASK_RUNNING and removes itself from the wait queue.
If the list is nonempty, the thread calls run_workqueue() to perform the deferred work.