CPU_TIME(TIME)不计等待时间

CPU_TIME(TIME)

Returns the CPU time, in seconds, taken by the current process and, possibly, 
all the child processes in all of the threads. A call to CPU_TIME will give the
processor time taken by the process from the start of the program. The time
measured only accounts for the amount of time that the program is actually running, and not the time that a program is suspended or waiting.