| Re: [chrony-users] Fwd: Chrony malfunctioning at beaglebones |
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On Sun, Aug 16, 2015 at 07:51:01PM +0100, Nuno Gonçalves wrote:
> Hi,
>
> Chrony at armv7l, a Beaglebone running Debian 8.1 (linux 4.1.5) looks
> to be broken.
>
> I have tested both a Beaglebone white and a Beaglebone black.
>
> I have tested with the Debian package (1.30), 2.1.1, and git HEAD.
>
> So, usually Chrony does sync the clock, but gives weird frequency estimates.
>
> Since this devices don't have a RTC, I have tried to start chrony both
> with a time way in the past, but also with a "correct" time already
> set.
>
> Machine 1:
>
> debian@bbw1:~$ chronyc sources
> 210 Number of sources = 3
> MS Name/IP address Stratum Poll Reach LastRx Last sample
> ===============================================================================
> ^+ a88-157-128-22.cpe.netcab 3 8 37 174 +68ms[ +268ms] +/- 66ms
> ^+ adsl-62-48-148-210.ptprim 3 8 37 174 +52ms[ +252ms] +/- 71ms
> ^* ntp1.unixcraft.org 2 8 37 173 +114ms[ +314ms] +/- 68ms
> debian@bbw1:~$ chronyc sourcestats
> 210 Number of sources = 3
> Name/IP Address NP NR Span Frequency Freq Skew Offset Std Dev
> ==============================================================================
> a88-157-128-22.cpe.netcab 5 3 9 +43847.180 151084 +7882ms 65ms
> adsl-62-48-148-210.ptprim 5 3 8 +45060.492 169101 +8104ms 75ms
> ntp1.unixcraft.org 5 3 9 +37482.402 234556 +6671ms 83ms
It looks like the output was captured soon after chronyd was started.
With only 4 measurements spread over 9 seconds such large frequency
error wouldn't be unusual. What do you see when chronyd is running for
an hour?
To further debug this it might be useful to configure chronyd to not
touch the clock by adding the noselect option to all servers specified
in the config file and enable the measurements and statistics logs
(see the logdir and log directives).
It could be a bug in the clock source that is used on the BB. You
could try a different clock source if there is more than one
available.
To see the current and all available clock sources:
cat /sys/devices/system/clocksource/clocksource0/current_clocksource
cat /sys/devices/system/clocksource/clocksource0/available_clocksource
To select a different clock source:
echo ??? > /sys/devices/system/clocksource/clocksource0/current_clocksource
--
Miroslav Lichvar
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