[Xen-devel] Possible hint for "Clocksource tsc unstable" problem

[Andreas Kinzler <ml-xen-devel@xxxxxx>]

Hello,

I made an interesting observation related to the "Clocksource tsc 
unstable (delta = -2999660320319 ns)" problem. In the log of ntpd I found:
Oct  5 03:46:35 greenville-dom0 ntpd[4020]: kernel time sync status 
change 6001
Oct  5 04:03:41 greenville-dom0 ntpd[4020]: kernel time sync status 
change 2001
Oct  5 05:29:03 greenville-dom0 ntpd[4020]: kernel time sync status 
change 6001
Oct  5 05:46:09 greenville-dom0 ntpd[4020]: kernel time sync status 
change 2001
Oct  5 06:54:30 greenville-dom0 ntpd[4020]: synchronized to 
192.53.103.104, stratum 1
Oct  5 06:54:30 greenville-dom0 ntpd[4020]: kernel time sync status 
change 6001
Oct  5 07:28:22 greenville-dom0 ntpd[4020]: kernel time sync status 
change 2001
Oct  5 08:19:35 greenville-dom0 ntpd[4020]: synchronized to 
192.53.103.108, stratum 1
Oct  5 10:53:26 greenville-dom0 ntpd[4020]: kernel time sync status 
change 6001
Oct  5 11:27:32 greenville-dom0 ntpd[4020]: kernel time sync status 
change 2001
Oct  5 12:01:41 greenville-dom0 ntpd[4020]: kernel time sync status 
change 6001
Oct  5 12:18:44 greenville-dom0 ntpd[4020]: kernel time sync status 
change 2001
Oct  5 13:09:58 greenville-dom0 ntpd[4020]: kernel time sync status 
change 6001
Oct  5 13:27:04 greenville-dom0 ntpd[4020]: kernel time sync status 
change 2001
Oct  5 15:26:37 greenville-dom0 ntpd[4020]: kernel time sync status 
change 6001
Oct  5 15:43:41 greenville-dom0 ntpd[4020]: kernel time sync status 
change 2001
Oct  5 17:43:11 greenville-dom0 ntpd[4020]: kernel time sync status 
change 6001
Oct  5 19:08:31 greenville-dom0 ntpd[4020]: synchronized to 
192.53.103.104, stratum 1
Oct  5 19:08:31 greenville-dom0 ntpd[4020]: kernel time sync status 
change 2001
Oct  5 21:23:58 greenville-dom0 ntpd[4020]: no servers reachable
Oct  5 21:40:58 greenville-dom0 ntpd[4020]: synchronized to 
192.53.103.104, stratum 1
Oct  5 21:40:58 greenville-dom0 ntpd[4020]: time correction of -3000 
seconds exceeds sanity limit (1000); set clock manually to the correct 
UTC time.
I had the problem twice on different machines but everytime I saw the 
line "no servers reachable". Could ntpd and/or linux kernel make some 
stupid stuff when ntp upstream servers are unreachable?
Regards Andreas


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