| Re: [chrony-users] How to avoid oversteering |
[ Thread Index |
Date Index
| More chrony.tuxfamily.org/chrony-users Archives
]
chronyd should not be doing that. It has a very efficient way of determining
what the correct rate should be, and uses an extra drift to drive the offset
to zero.
Is this on real hardware on a virtual machine? Chrony should not be run on
virtual machines, because the timing on those is a mess. Their internal clocks
are not regular.
Alternatively it could be a severe hardware issue, or you could be running the
system on a tickless clock.
On Mon, 5 Feb 2018, Ariel Garcia wrote:
Hello,
i am trying to get Chrony 3.2 running without stepping the clock, but i
find that it oversteers by a huge amount. I observe that it starts driving
the system clock to the right value, but then moves it more that the
initial offset in the opposite direction, and starts "oscillating".
I rebooted to make sure the system clock runs at the "default" speed
initially, having previously set the RTC ~10s off from the correct time
for testing. After chrony started it reported:
System time : 10.891304016 seconds slow of NTP time
After ~ 10 minutes running it was already:
System time : 2.529696226 seconds slow of NTP time
but then after ~20 minutes it was already in the opposite direction:
System time : 12.160170555 seconds fast of NTP time
After one hour running it is worse than at the beginning:
System time : 16.009445190 seconds slow of NTP time
What am i doing wrong, am i having the wrong expectation, or could
it be a hardware or a configuration issue?
(the drift values shown above are consistent with the device's RTC
--which is not being adjusted-- and an external PC)
I've tried to collect all details below,
thanks in advance for any hints/help!!
Ariel
================================================================
Running on a BeagleBone black-similar board, with an AM335X CPU.
My configuration was chosen as simple as possible to start:
--------------------------------
pool de.pool.ntp.org minpoll 4
makestep 3600 3
logchange 0.05
cmdallow 127.0.0.1
bindcmdaddress /run/chrony/chronyd.sock
pidfile /run/chrony/chronyd.pid
-------------------------------
Of course i made sure there is no other NTP daemon running.
These are all running processes (only deleted my open ssh connections)
--------------------------------
1 ? Ss 0:10 /sbin/init
978 ? Ss 0:03 /usr/sbin/rngd -f
985 ? Ss 0:04 /lib/systemd/systemd-journald
1773 ? Ss 0:00 /lib/systemd/systemd-udevd
1805 ttyO0 Ss+ 0:00 /sbin/agetty --keep-baud 115200 38400 9600 ttyO0 vt220
1812 ? Ss 0:00 /usr/bin/dbus-daemon --system --address=systemd: --nofork --nopidfile --systemd-activation
1813 ? Ss 0:00 /usr/sbin/crond -b
1827 ? Ss 0:00 /lib/systemd/systemd-networkd
1834 ? Ss 0:00 /lib/systemd/systemd-resolved
15344 ? S 0:00 /usr/sbin/chronyd -4 -f /etc/chrony/chrony.conf
--------------------------------
The servers are reachable and seem ok:
--------------------------------
$ chronyc -n sources
210 Number of sources = 4
MS Name/IP address Stratum Poll Reach LastRx Last sample
===============================================================================
^- 172.104.239.150 2 4 377 3 -1158ms[-1158ms] +/- 58ms
^- 138.201.135.108 2 4 377 4 -1057ms[-1057ms] +/- 47ms
^* 195.34.187.132 2 4 377 14 +17ms[-1527ms] +/- 28ms
^- 5.9.78.71 2 4 377 13 -142ms[ -142ms] +/- 50ms
$ chronyc -n sourcestats
210 Number of sources = 4
Name/IP Address NP NR Span Frequency Freq Skew Offset Std Dev
==============================================================================
172.104.239.150 6 3 75 -103422 1668.695 -1033ms 14ms
138.201.135.108 6 3 75 -103305 1165.815 -1020ms 11ms
195.34.187.132 6 3 75 -103052 2391.831 -1021ms 15ms
5.9.78.71 6 3 75 -102973 2085.425 -1017ms 14ms
--------------------------------
The logs show
---------------------------------
Feb 05 17:18:22 BBx systemd[1]: Starting NTP client/server...
Feb 05 17:18:22 BBx chronyd[15344]: chronyd version 3.2 starting (+CMDMON +NTP +REFCLOCK +RTC +PRIVDROP -SCFILTER -SECHASH -SIGND +ASYNCDNS +IPV6 -DEBUG)
Feb 05 17:18:22 BBx chronyd[15344]: Initial frequency 42.124 ppm
Feb 05 17:18:22 BBx systemd[1]: Started NTP client/server.
Feb 05 17:18:55 BBx chronyd[15344]: Selected source 129.70.132.35
Feb 05 17:18:56 BBx chronyd[15344]: System clock wrong by 11.087803 seconds, adjustment started
Feb 05 17:19:11 BBx chronyd[15344]: Can't synchronise: no majority
Feb 05 17:19:12 BBx chronyd[15344]: Selected source 129.70.132.35
Feb 05 17:19:12 BBx chronyd[15344]: System clock wrong by 1.096591 seconds, adjustment started
Feb 05 17:19:27 BBx chronyd[15344]: Selected source 138.201.135.108
Feb 05 17:19:27 BBx chronyd[15344]: System clock wrong by 0.943644 seconds, adjustment started
Feb 05 17:19:43 BBx chronyd[15344]: System clock wrong by 1.241887 seconds, adjustment started
...
(lots or similar lines, but always the system clock is reported to be wrong
by +2 to -2 seconds, never by the amount shown by "chronyc tracking")
...
---------------------------------
The tracking data at different times:
---------------------------------
$ chronyc tracking
Reference ID : 81468423 (stratum2-2.NTP.TechFak.NET)
Stratum : 3
Ref time (UTC) : Mon Feb 05 17:19:05 2018
System time : 10.891304016 seconds slow of NTP time
Last offset : -11.087802887 seconds
RMS offset : 11.087802887 seconds
Frequency : 42.124 ppm fast
Residual freq : +1.113 ppm
Skew : 1000000.000 ppm
Root delay : 0.037714522 seconds
Root dispersion : 3.768865824 seconds
Update interval : 0.0 seconds
Leap status : Normal
---------------------------------
$ chronyc tracking
Reference ID : 8AC9876C (srv23.globale-gruppe.com)
Stratum : 3
Ref time (UTC) : Mon Feb 05 17:19:37 2018
System time : 9.804729462 seconds slow of NTP time
Last offset : -0.943643808 seconds
RMS offset : 0.943643808 seconds
Frequency : 42.124 ppm fast
Residual freq : -41046.902 ppm
Skew : 1000000.000 ppm
Root delay : 0.033498995 seconds
Root dispersion : 12.330061913 seconds
Update interval : 14.3 seconds
Leap status : Normal
---------------------------------
$ chronyc tracking
Reference ID : 81468423 (stratum2-2.NTP.TechFak.NET)
Stratum : 3
Ref time (UTC) : Mon Feb 05 17:24:13 2018
System time : 9.454131126 seconds slow of NTP time
Last offset : +0.030433958 seconds
RMS offset : 0.640062451 seconds
Frequency : 90705.453 ppm slow
Residual freq : +86.611 ppm
Skew : 1054.889 ppm
Root delay : 0.035278354 seconds
Root dispersion : 0.017751774 seconds
Update interval : 16.1 seconds
Leap status : Normal
---------------------------------
$ chronyc tracking
Reference ID : 81468423 (stratum2-2.NTP.TechFak.NET)
Stratum : 3
Ref time (UTC) : Mon Feb 05 17:31:07 2018
System time : 2.529696226 seconds slow of NTP time
Last offset : +0.029113885 seconds
RMS offset : 0.166937038 seconds
Frequency : 77410.445 ppm slow
Residual freq : +1074.334 ppm
Skew : 1991.644 ppm
Root delay : 0.035502460 seconds
Root dispersion : 0.027657172 seconds
Update interval : 15.8 seconds
Leap status : Normal
---------------------------------
$ chronyc tracking
Reference ID : 8AC9876C (srv23.globale-gruppe.com)
Stratum : 3
Ref time (UTC) : Mon Feb 05 17:37:24 2018
System time : 6.902931690 seconds fast of NTP time
Last offset : +0.189766780 seconds
RMS offset : 1.233845592 seconds
Frequency : 108520.094 ppm fast
Residual freq : +12504.339 ppm
Skew : 30318.885 ppm
Root delay : 0.034667145 seconds
Root dispersion : 0.311530590 seconds
Update interval : 16.1 seconds
Leap status : Normal
---------------------------------
$ chronyc tracking
Reference ID : 81468423 (stratum2-2.NTP.TechFak.NET)
Stratum : 3
Ref time (UTC) : Mon Feb 05 17:45:10 2018
System time : 13.315183640 seconds fast of NTP time
Last offset : -0.028802348 seconds
RMS offset : 0.300014675 seconds
Frequency : 106800.570 ppm fast
Residual freq : -74.106 ppm
Skew : 1022.886 ppm
Root delay : 0.034821544 seconds
Root dispersion : 0.017649684 seconds
Update interval : 16.2 seconds
Leap status : Normal
---------------------------------
$ chronyc tracking
Reference ID : C322BB84 (powered.by.inet.de)
Stratum : 3
Ref time (UTC) : Mon Feb 05 18:06:29 2018
System time : 4.486146450 seconds slow of NTP time
Last offset : -0.437962651 seconds
RMS offset : 1.165199637 seconds
Frequency : 19659.746 ppm slow
Residual freq : -14884.478 ppm
Skew : 39623.336 ppm
Root delay : 0.025750067 seconds
Root dispersion : 0.237240255 seconds
Update interval : 3.7 seconds
Leap status : Normal
---------------------------------
$ chronyc tracking
Reference ID : C322BB84 (powered.by.inet.de)
Stratum : 3
Ref time (UTC) : Mon Feb 05 18:19:55 2018
System time : 16.009445190 seconds slow of NTP time
Last offset : +0.026499212 seconds
RMS offset : 0.694284379 seconds
Frequency : 102772.656 ppm slow
Residual freq : +110.795 ppm
Skew : 1070.995 ppm
Root delay : 0.027395297 seconds
Root dispersion : 0.030097129 seconds
Update interval : 16.3 seconds
Leap status : Normal
---------------------------------
$ chronyc tracking
Reference ID : AC68EF96 (watch.no-such-agency.net)
Stratum : 3
Ref time (UTC) : Mon Feb 05 18:52:14 2018
System time : 17.909534454 seconds fast of NTP time
Last offset : -0.021534055 seconds
RMS offset : 0.502140403 seconds
Frequency : 106267.859 ppm fast
Residual freq : -85.290 ppm
Skew : 1018.805 ppm
Root delay : 0.025392590 seconds
Root dispersion : 0.026234277 seconds
Update interval : 13.1 seconds
Leap status : Normal
---------------------------------
--
To unsubscribe email chrony-users-request@xxxxxxxxxxxxxxxxxxxx
with "unsubscribe" in the subject.
For help email chrony-users-request@xxxxxxxxxxxxxxxxxxxx
with "help" in the subject.
Trouble? Email listmaster@xxxxxxxxxxxxxxxxxxxx.
--
To unsubscribe email chrony-users-request@xxxxxxxxxxxxxxxxxxxx
with "unsubscribe" in the subject.
For help email chrony-users-request@xxxxxxxxxxxxxxxxxxxx
with "help" in the subject.
Trouble? Email listmaster@xxxxxxxxxxxxxxxxxxxx.