Is it OK to modify _TOD_Ticks_per_second?

[Till Straumann]

I'm thinking about synchronizing the system clock
with NTP. One obvious method which avoids leaps
back in time would be letting a feedback loop
control the clock tick rate.

There is no API to set the system clock rate.
Do you think it would be easy to add one to
set _TOD_Ticks_per_second? Or are there silent
assumptions that the clock rate never changes
(even by small amounts)?

-- Till