[ntp:questions] ntpd -x option

Matthias Fuchs matthias.fuchs at esd-electronics.com
Thu Mar 12 10:03:38 UTC 2009

Unruh wrote:

> Matthias Fuchs <matthias.fuchs at esd-electronics.com> writes:
>>I am trying to understand ntpd's -x option. From the ntpd documentation
>>I expect ntpd to adjust the (system-)time in all situations when -x
>>is used. The only exception I see is when the system time is totally wrong
>>(more than 1000s) ntpd will see this as an error and exit. This can be
>>avoided through the "tinker panic 0" configuration.
>>But now, when I start ntpd with the -x option and an offset of
>>about 30s before ntpd is started, I get error messages like this
>>        frequency error 557 PPM exceeds tolerance 500 PPM
>>Also there seems to be not regulation at all and ntptime reports
>>~# ntptime
>>ntp_gettime() returns code 5 (ERROR)
>>  time cd624627.39886000  Wed, Mar 11 2009 15:16:07.224, (.224737),
>>  maximum error 993296 us, estimated error 16 us
>>ntp_adjtime() returns code 5 (ERROR)
>>  modes 0x0 (),
>>  offset 0.000 us, frequency 0.000 ppm, interval 1 s,
>>  maximum error 993296 us, estimated error 16 us,
>>  status 0x40 (UNSYNC),
>>  time constant 4, precision 1.000 us, tolerance 512 ppm,
>>I am using two remote stratum 1 NTP servers for these tests.
>>So is there any way to make ntpd _adjust_ the time in all situations?
>>I am aware of the maximum adjustment of 500ppm (0.5ms/s). I would be lucky
>>if ntpd could adjust the above offset (30s) in a day or so.
>>I not want ntpd to step my system time! Not even once during initial
> Do not use ntp. Use chrony instead. It has a far far faster adjustment.
> However, it only runs on Linux.

I thought about usig chrony, but I need hardware reference clocks as well
(DCF77 or GPS). This works with ntpd but chrony does not seem to support


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