Odd behaviour on recent boot of 11.1 with timecounters

[Konstantin Belousov]

On Sun, Dec 31, 2017 at 02:17:08PM +0000, Gary Palmer wrote:
> 
> Hi,
> 
> I recently updated to 11.1-RELEASE-p6 and on the most recent reboot 
> (after rebuilding all the necessary packages) the clock was running 
> slow and NTP wouldn't sync.  I looked in /var/log/messages and I found
> that for some reason, on this latest boot, it got the frequency of
> TSC-low wrong.
> 
> Aug 24 04:55:35 my kernel: Timecounter "TSC-low" frequency 1746073190 Hz quality 1000
> Aug 26 03:11:38 my kernel: Timecounter "TSC-low" frequency 1746070760 Hz quality 1000
> Aug 26 14:12:46 my kernel: Timecounter "TSC-low" frequency 1746075204 Hz quality 1000
> Nov 19 16:01:09 my kernel: Timecounter "TSC-low" frequency 1746070746 Hz quality 1000
> Dec 27 22:28:00 my kernel: Timecounter "TSC-low" frequency 1746074808 Hz quality 1000
> Dec 27 22:51:12 my kernel: Timecounter "TSC-low" frequency 1746071892 Hz quality 1000
> Dec 28 12:50:46 my kernel: Timecounter "TSC-low" frequency 1746069704 Hz quality 1000
> Dec 28 14:03:52 my kernel: Timecounter "TSC-low" frequency 1937876448 Hz quality 1000
> 
> Until the December reboots the machine was running 10.x.  Dec 27 and later
> are part of the process to get up to 11.x.
> 
> Any idea why the TSC-low frequency jumped 191,806,744Hz on the last
> measurement?
> 
> I switched to HPET temporarily via sysctl and ntp seems happy.  I'm just
> concerned that the problem might recur on later reboots as TSC-low seems
> to be the preferred timecounter.

Show first 100 lines of the dmesg from a verbose boot.
Also check BIOS settings related to overclocking and powersaving.