a package named 'adjtimex' has hit the untested repo. i thought it may be of some use to people with older hardware. at any rate it looked interesting. here is a quick snip from its readme
You probably already know that your computer has two clocks - the "real
time clock" (RTC) that runs all the time, and the system clock that runs
only while the computer is on. The system clock has much better
precision (approximately 1 usec), but the RTC probably has better
long-term stability. adjtimex can be used to approximately correct the
system clock for drift.
The handiest reference clock is the RTC.
shows the time, the difference between the two clocks, the first
difference (how much the system clock has gained or lost relative to
the RTC since the last check), and two kernel time parameters: tick
and frequency offset. After the first two comparisons, it also prints
suggested values of tick and frequency offset that will adjust the
system clock to approximately agree with the RTC. Of course, the RTC
may have a systematic error of its own. clock(8) uses the file
/etc/adjtime to record the drift rate and the time since the RTC was
last set. adjtimex also consults this file and applies the correction
to the times from the RTC.