I'm reading the "Linux Kernel Development" by Robert Love. in the Chapter 11 "Timers and Time Management" he mentioned that:
The kernel defines the value in <asm/param.h>.The tick rate has afrequency of HZ hertz and a period of 1/HZ seconds. For example, bydefault the x86 architecture defines HZ to be 100.Therefore, the timerinterrupt on i386 has a frequency of 100HZ and occurs 100 times persecond (every one-hundredth of a second, which is every 10milliseconds). Other common values for HZ are 250 and 1000,corresponding to periods of 4ms and 1ms, respectively.
I'm thinking that the monitor refresh should be also a timer-based event, but the refresh rate is 60Hz or 120Hz, seems this value can not be divided by 100,250 or 1000.