[chrony-dev] chronyd feature request: aggressive mode

["Gerriet M. Denkmann" <gerrietm@xxxxxxxxxx>]

chronyd does a good job of keeping the time in sync without big changes in the drift (freuquency).

But there are a few situations, where an “aggressive mode” (i.e. drastically increasing the frequency) would be more appropriate:

(1) at start
(2) when there is a big time-error (ntp-time - cpu-time) (e.g. > 2 sec)
(3) (at least on macOS) when the computer wakes up from sleep.

(1) my computer usually runs for months without shut-down or reboot.
So maybe chronyd already does the right thing in this situation.

(2) I have seen rather big frequencies (up to 20-fold of normal drift resulting from a time-error of 45 sec).
So this case also seems to be handled ok. 

(3) On macOS there is usually a time-error of -1 … +2 seconds upon wake up. (rarely more than 2 sec) (this is only true with rtcsync working).
The problem here: when chronyd thinks that all is stable, the next check with ntp might by delayed by up to 17 min (sometime up to 53  min).
And for usual errors < 2 sec, case (2) does not apply. This results in almost an hour (depending of course on the wake-up error) until the time is correct again.
Here I would like to see an “aggressive mode” until the time-error is down to a few msec.

Would this be possible?
Or are there reasons, why this is *not* a good idea?

Gerriet.


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