15天入门RT-THREAD学习-第四天(空闲任务及其钩子函数)

发布于 2018-05-21 09:10:57 浏览：2089 订阅该版

1、前期疑问解答
2、空闲任务必要性探讨
main
{
	while(1)
	{
		led;
		key;
		nrf;
		display;
		;	
	}
}
空闲任务的目的是在没有应用线程运行时让CPU有事可做
3、空闲任务优先级
空闲任务的优先级是最低的
空闲任务的优先级为RT_THREAD_PRIORITY_MAX - 1
如果需要使用空闲任务钩子函数时需要调整空闲任务的堆栈大小
4、空闲任务钩子函数的使用场合
空闲钩子函数就是空闲任务在运行时调用的函数
空闲钩子函数通常用于：
A\执行低优先级的任务、或后台任务或者需要不停处理的功能
B\测试系统的处理裕量（如CPU的使用率）
要使用空闲钩子函数必须将宏RT_USING_IDLE_HOOK设置为1
5、cpu使用率统计的实现原理
   cpu使用率 = 100 - cpu空闲率
   
作业：
1、修改系统滴答时钟，观察系统滴答时钟频率对CPU使用率的影响
------------------------------------------------
#define RT_TICK_PER_SECOND 100
 \ | /
- RT -     Thread Operating System
 / | \     3.0.4 build May 21 2018
 2006 - 2018 Copyright by rt-thread team
msh >c
cpu_usage_init
msh >cpu_usage_init
msh >cpu usage: 0.0%
cpu usage: 0.0%
cpu usage: 0.0%
cpu usage: 0.0%
cpu usage: 0.0%
cpu usage: 0.1%
cpu usage: 0.1%
cpu usage: 0.0%
cpu usage: 0.0%

-------------------------------------------------
#define RT_TICK_PER_SECOND 500
 \ | /
- RT -     Thread Operating System
 / | \     3.0.4 build May 21 2018
 2006 - 2018 Copyright by rt-thread team
msh >c
cpu_usage_init
msh >cpu_usage_init
msh >cpu usage: 0.0%
cpu usage: 0.7%
cpu usage: 0.7%
cpu usage: 0.7%
cpu usage: 0.7%
cpu usage: 0.7%
cpu usage: 0.0%
cpu usage: 0.0%
cpu usage: 0.0%
cpu usage: 0.7%
cpu usage: 0.7%
cpu usage: 0.7%
cpu usage: 0.7%
cpu usage: 0.7%

-------------------------------------------------
#define RT_TICK_PER_SECOND 1000
 \ | /
- RT -     Thread Operating System
 / | \     3.0.4 build May 21 2018
 2006 - 2018 Copyright by rt-thread team
msh >c
cpu_usage_init
msh >cpu_usage_init
msh >cpu usage: 0.0%
cpu usage: 0.0%
cpu usage: 0.15%
cpu usage: 0.0%
cpu usage: 0.0%
cpu usage: 0.0%
cpu usage: 0.0%
cpu usage: 0.15%
cpu usage: 0.0%
cpu usage: 0.0%
cpu usage: 0.0%
cpu usage: 0.0%
2、将使用率修改为float或double看看CPU使用的变化
static float  cpu_usage_major = 0, cpu_usage_minor = 0;
-------------------------------------------------
#define RT_TICK_PER_SECOND 100
CPU使用率打印线程中rt_thread_delay(40);
 \ | /
- RT -     Thread Operating System
 / | \     3.0.4 build May 21 2018
 2006 - 2018 Copyright by rt-thread team
msh >c
cpu_usage_init
msh >cpu_usage_init
msh >cpu usage: 0.0%
cpu usage: 0.0%
cpu usage: 0.0%
cpu usage: 0.0%
cpu usage: 0.15644000%
cpu usage: 0.15644000%
cpu usage: 0.15644000%
cpu usage: 0.15644000%
cpu usage: 0.15644000%
cpu usage: 0.0%

-------------------------------------------------
#define RT_TICK_PER_SECOND 500
CPU使用率打印线程中rt_thread_delay(50);
 \ | /
- RT -     Thread Operating System
 / | \     3.0.4 build May 21 2018
 2006 - 2018 Copyright by rt-thread team
msh >c
cpu_usage_init
msh >cpu_usage_init
msh >cpu usage: 0.0%
\cpu usage: 0.0%
cpu usage: 0.78000%
cpu usage: 0.0%
cpu usage: 0.78000%
cpu usage: 0.78000%
cpu usage: 0.78000%
cpu usage: 0.78000%
cpu usage: 0.0%
cpu usage: 0.78000%

2 个回答

liaoxu02 2018-05-31

这家伙很懒，什么也没写！

coolbor 2018-06-01

这家伙很懒，什么也没写！

>你好，能把你将使用率修改为float或double看看CPU使用率的代码给我参考一下吗？ ...

---

#define RT_TICK_PER_SECOND 100
static double  cpu_usage_major = 0, cpu_usage_minor = 0;
运行结果：

```

\ | /
- RT -     Thread Operating System
 / | \     3.0.4 build May 30 2018
 2006 - 2018 Copyright by rt-thread team
msh >cpu
cpu_usage_init
msh >cpu_usage_init
msh >cpu usage: 0.0%
cpu usage: 0.0%
cpu usage: 0.4693366%
cpu usage: 0.4693366%
cpu usage: 0.3128911%
cpu usage: 0.4693366%
cpu usage: 0.4693366%
cpu usage: 0.3128911%
cpu usage: 0.3128911%

```

---------------------------------------------------------------------------------------------------
#define RT_TICK_PER_SECOND 100
static float  cpu_usage_major = 0, cpu_usage_minor = 0;
运行结果：

```
 \ | /
- RT -     Thread Operating System
 / | \     3.0.4 build May 30 2018
 2006 - 2018 Copyright by rt-thread team
msh >cpu
cpu_usage_init
msh >cpu_usage_init
msh >cpu usage: 0.0%
cpu usage: 0.1564455%
cpu usage: 0.1564455%
cpu usage: 0.1564455%
cpu usage: 0.1564455%
cpu usage: 0.1564455%
cpu usage: 0.1564455%
cpu usage: 0.1564455%
cpu usage: 0.1564455%
cpu usage: 0.1564455%
```