关于UC/OS-II中OS_TaskStat()函数的简单有关问题

关于UC/OS-II中OS_TaskStat()函数的简单问题
函数的核心代码如下：
void OS_TaskStat (void *pdata)
{
  INT32U run;
  INT8S usage;

  while (OSStatRdy == FALSE) {
  OSTimeDly(2 * OS_TICKS_PER_SEC); /* Wait until statistic task is ready */
  }
  for (;;) {
  OS_ENTER_CRITICAL();
  OSIdleCtrRun = OSIdleCtr; /* Obtain the of the idle counter for the past second */
  run = OSIdleCtr;
  OSIdleCtr = 0L; /* Reset the idle counter for the next second */
  OS_EXIT_CRITICAL();
  if (OSIdleCtrMax > 0L) {
  usage = (INT8S)(100L - 100L * run / OSIdleCtrMax);
  if (usage >= 0) { /* Make sure we don't have a negative percentage */
  OSCPUUsage = usage;
  } else {
  OSCPUUsage = 0;
  }
  } else {
  OSCPUUsage = 0;
  }
  OSTaskStatHook(); /* Invoke user definable hook */
  OSTimeDly(OS_TICKS_PER_SEC); /* Accumulate OSIdleCtr for the next second */
  }
}
函数的作用是计算CPU的占用情况，对吧，我知道OSIdleCtrMax是在只有空闲任务时单位时间的计数，而OSIdleCtr应该是当前单位时间内空闲任务计数啊，可是为什么没有体现出这一点。我觉得应该先把OSIdleCtr清零，再延时1秒，这时的OSIdleCtr才可用

------解决方案--------------------
去看看邵贝贝的那本书吧。