Maintaining a system clock that can be read by any user program requires only that the operating system read a physical device (keeping physical time) and then write the time into a globally readable variable. Suppose the time to read the physical clock and to update the variable is 100 microseconds. What percentage of the total CPU time is spent maintaining a clock that is accurate to the millisecond resolution (that is, the clock always reflects the correct time to the closest millisecond)? The 100 microsecond resolution? The 10 microsecond resolution? Explain your rationale.