Linux源码阅读笔记08-进程调度API系统调用案例分析

kthread_create_on_node

kthread_create_on_node函数功能：指定存储节点创建新内核线程。源码如下：

操作实战

#include <linux/module.h>
#include <linux/pid.h>
#include <linux/sched.h>
#include <linux/kthread.h>
#include <linux/wait.h>int MyThreadFunc(void* argc) {printk("MyThreadFunc\n");printk("MyThreadFuncPID: %d\n", current->pid);printk("Exit MyThreadFunc\n");return 0;
}static int __init KthreadCreateOnNodeInit(void) {struct task_struct* pts = NULL;printk("KthreadCreateOnNodeInit\n");pts = kthread_create_on_node(MyThreadFunc, NULL, -1, "ktconode.c");printk("New thread PID: %d\n", pts->pid);wake_up_process(pts);printk("Curretn thread PID: %d\n", current->pid);return 0;
}static void __exit KthreadCreateOnNodeExit(void) {printk("Exit kernel: KthreadCreateOnNodeExit\n");
}MODULE_LICENSE("GPL");
module_init(KthreadCreateOnNodeInit);
module_exit(KthreadCreateOnNodeExit);

wake_up_process

wake_up_process函数功能：唤醒处于睡眠状态的进程，状态转换为RUNNING状态，让CPU重新调度处理。

• 唤醒成功返回1
• 唤醒失败（该线程已经是RUNNING状态）返回0

源代码如下：

操作实战

#include <linux/kthread.h>
#include <linux/sched.h>
#include <linux/wait.h>
#include <linux/module.h>
#include <linux/pid.h>
#include <linux/list.h>
#include <linux/delay.h>struct task_struct* pts_thread = NULL;int MyThreadFunc(void* argc) {int iData = -1;printk("MyThreadFunc\n");printk("MyThreadFunc PID: %d\n", current->pid);//查看父进程状态printk("初始化函数状态为: %ld\n", pts_thread->state);iData = wake_up_process(pts_thread);printk("wake_up_process之后父进程状态: %ld\n", pts_thread->state);printk("wake_up_process返回结果为: %d\n", iData);printk("Exit MyThreadFunc\n");return 0;
}static int __init WakeUpProcessInit(void) {int res = 1; // 保存wake_up_process结果char cName[] = "wakeup.c%s";struct task_struct* pResult = NULL;long time_out;wait_queue_head_t head;wait_queue_entry_t data;printk("WakeUpProcessInit\n");//指定节点，创建新的内核线程pResult = kthread_create_on_node(MyThreadFunc, NULL, -1, cName);printk("New thread PID: %d\n", pResult->pid);printk("Current thread PID: %d\n", current->pid);init_waitqueue_head(&head);init_waitqueue_entry(&data, current);add_wait_queue(&head, &data);pts_thread = current;res = wake_up_process(pResult);printk("wake_up_process唤醒新线程之后的结果为: %d\n", res);time_out = schedule_timeout_uninterruptible(2000*10);res = wake_up_process(current);printk("唤醒当前线程的结果为: %d\n", res);printk("调用sched_timeout_uninterruptible返回结果为: %ld\n", time_out);printk("Exit WakeUpProcessInit\n");return 0;
}static void __exit WakeUpProcessExit(void) {printk("Exit WakeUpProcessExit\n");
}module_init(WakeUpProcessInit);
module_exit(WakeUpProcessExit);