Functions like GetTickCount() need to read the tick count which is updated by the interrupt. Changing the behavior of GetTickCount() would be difficult and woul

Functions like GetTickCount() need to read the tick count which is updated by the interrupt. Changing the behavior of GetTickCount() would be difficult and would likely be less efficient. So, NT can't become completely tickless - there needs to be an interrupt to increment that counter. Realistically there will almost always be some thread that wants to wake up then so the recurring interrupt probably doesn't cost anything.