5 rt-thread关于CPU使用率的计算

发布于 2021-07-12 14:27:21 浏览：1440 订阅该版

看到rtt关于cpu使用率统计的代码，代码如下：
```c
static void cpu_usage_idle_hook(void)
{
    rt_tick_t tick;
    rt_uint32_t count;
    volatile rt_uint32_t loop;

if (total_count == 0)
    {
        /* get total count */
        rt_enter_critical();
        tick = rt_tick_get();
        while(rt_tick_get() - tick < CPU_USAGE_CALC_TICK)
        {
            total_count ++;
            loop = 0;

while (loop < CPU_USAGE_LOOP) loop ++;
        }
        rt_exit_critical();
    }

count = 0;
    /* get CPU usage */
    tick = rt_tick_get();
    while (rt_tick_get() - tick < CPU_USAGE_CALC_TICK)
    {
        count ++;
        loop  = 0;
        while (loop < CPU_USAGE_LOOP) loop ++;
    }

/* calculate major and minor */
    if (count < total_count)
    {
        count = total_count - count;
        cpu_usage_major = (count * 100) / total_count;
        cpu_usage_minor = ((count * 100) % total_count) * 100 / total_count;
    }
    else
    {
        total_count = count;

/* no CPU usage */
        cpu_usage_major = 0;
        cpu_usage_minor = 0;
    }
}
```
关于total_count在系统不调度情况下的累加值作为以后计算cpu使用率的基准，但是在计算这个值得时候，这行代码有什么用呢?
```c
    loop = 0;
    while (loop < CPU_USAGE_LOOP) loop ++;
```