High resource usage of the Program System

The resource usage of the program system is too high-Linux general technology-Linux programming and kernel information. The following is a detailed description. 15:38:31% usr % sys % wio % idle (-u)
15:38:32 0 0 100
15:38:33 0 0 100
15:38:34 0 4 58 38
15:38:35 0 1 99 0
15:38:36 0 4 25 71
15:38:37 0 0 100
15:38:38 0 11 0 89
15:38:39 0 1 0 99
15:38:40 0 0 100
15:38:41 0 4 32 64
15:38:42 0 0 100 0
15:38:43 0 0 100 0
15:38:44 0 2 48 50
15:38:45 0 0 100
15:38:46 0 12 0 88

Program:

Timer
{
Fun; // time-to-call Function
Interval; // interval
Remain; // remaining time
}
Signal (SIGALARM, TimFun)
Alarm (1)

Timer Tim [MAX];
TimFun ()
{
For (I = 0; I <MAX; I ++)
{
Tim . Remain --;
If (Tim. Remain <= 0)
{
Run (Tim. Fun); // call the function regularly
Tim. Remain = Tim. Interval // Reset
}
Signal (SIGALARM, TimFun );
Alarm (1 );
}


What is the main cause of high resource usage !! (It should not be the Tim function called.. The reason for fun, because after using another method to call all the fun, the endless loop + sleep in fun won't have such a high resource usage)