Re: Bug report: `maxslewrate` violation by chrony
Miroslav Lichvar <[email protected]>
| Newsgroups | gmane.comp.time.chrony.user |
|---|---|
| Message-ID | <Y48Bm7xENSV60nkw@localhost> |
On Mon, Dec 05, 2022 at 05:14:10PM -0800, Adam Snaider wrote: > Hi folks, > > I wanted to report a bug. We use chrony for time synchronization and we > have a strict requirement that forces us to limit the slew rate to no more > than 250ppm. We noticed that in some conditions, chrony exceeds this limit > by >10x. I've collected an strace that shows chrony is indeed the culprit > as it is calling the clock_adjtime syscall with the tick and frequency set > to 9980 and -140765 which corresponds to roughly -2002ppm. The values passed to clock_adjtime() correct both the estimated frequency error (drift) and phase error (slew). What frequency do you see reported in the tracking log when this happens? If I understand your test correctly, you are simulating an unstable clock, which could be measured as a large frequency offset. If you need to limit the sum of the two, you will need to set also the maxdrift option. -- Miroslav Lichvar -- To unsubscribe email chrony-users-request-kWFZVVI9zxvPqho9SqqRMmD2FQJk+8+b@public.gmane.org with "unsubscribe" in the subject. For help email chrony-users-request-kWFZVVI9zxvPqho9SqqRMmD2FQJk+8+b@public.gmane.org with "help" in the subject. Trouble? Email [email protected]