Re: Unable to move system time back on recent Core i7 systems
From: LuboÅ DoleÅel
Date: Tue Aug 29 2017 - 18:29:30 EST
Dne 30.8.2017 v 00:18 Randy Dunlap napsal(a):
On 08/29/17 12:10, Luboš Doležel wrote:
Hello,
I'm hitting a strange bug on some of my Linux systems with various 4.x kernels.
I cannot set the system time to anything before the current system time.
This includes ntpd not being able to keep the clock in sync if the system clock is a little too fast. So it's not limited to just setting the time back to the 90s, but it actually breaks time synchronization on my server system.
Essentially, settimeofday() and clock_settime() system calls succeed, but any subsequent gettimeofday() etc. call will return unaltered time.
E.g.:
$ sudo date -s 1998-08-01
Sat Aug 1 00:00:00 CEST 1998
$ date
Tue Aug 29 20:59:25 CEST 2017
Is ntp daemon running?
Nope, not at the time of the above experiment. Neither is systemd-timesyncd.
And when I do run the NTP daemon, it is unable to correct the time,
which is a major problem (over time as the system clock drifts).
See here:
# ntpq -p
remote refid st t when poll reach delay offset
jitter
==============================================================================
tik.cesnet.cz 195.113.144.238 2 u 19 64 3 19.153 -6787.7
0.793
yak.osoal.org.n .GPS. 1 u 17 64 3 315.400 -6786.8
0.983
golf.zq1.de 192.53.103.103 2 u 21 64 3 35.219 -6786.7
0.836
manager-vlan87. 193.6.222.95 2 u 18 64 3 39.147 -6791.1
0.807
stratum2-2.NTP. 129.70.130.70 2 u 21 64 3 37.787 -6786.8
0.885
All servers are reported to have a ~ -6700ms offset and it only grows
over time.
Are there any other known system services that could interfere with the
clock like this?
Lubos