Odd behaviour on recent boot of 11.1 with timecounters

[Chris H]

On Tue, 2 Jan 2018 16:45:26 +0000 "Gary Palmer" <gpalmer at freebsd.org> said

> On Sun, Dec 31, 2017 at 06:47:38PM +0200, Konstantin Belousov wrote:
> > On Sun, Dec 31, 2017 at 03:49:13PM +0000, Gary Palmer wrote:
> > > On Sun, Dec 31, 2017 at 04:51:47PM +0200, Konstantin Belousov wrote:
> > > > 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.
> > > > 
> > > 
> > > Hi Konstantin,
> > > 
> > > BIOS settings haven't been changed in 4+ years.  No overclocking, and
> > > all powersaving options are at "auto" or "disabled".
> > > 
> > > The first 100 lines of verbose dmesg didn't seem that interesting so
> > > I've included up to the end of "Device configuration finished"
> > > 
> > > Note that this boot didn't have the TSC-low problem, and the boot
> > > that had it wasn't verbose unfortunately.
> > 
> > It is really the CPU identification which I wanted to see.  You have
> > IvyBridge, which is known to have good TSC.
> 
> Ah
> 
> > Try to obtain verbose dmesg with mis-identified frequency.
> 
> Tried, and failed after 20+ reboots.  I've left
> 
> boot_verbose=" -v"
I believe that should read:

boot_verbose="YES"
but maybe just the occurrence of something makes it a positive.

> 
> in /boot/loader.conf to catch any boot-time wonkiness and undone it at
> runtime with 
> 
> debug.bootverbose=0
> 
> in /etc/sysctl.conf as I found that the snd_hda driver is ... chatty
> at runtime.
> 
> Thanks,
> 
> Gary
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