[RndTbl] system loses time

Trevor Cordes trevor at tecnopolis.ca
Tue Dec 11 14:35:55 CST 2012

On 2012-12-10 Trevor Cordes wrote:
> I have another system (not the same one with RTC problems).  It loses 
> about 1s every 1m in system time!!

I think I solved my own problem, after spending another hour on it :-(

A clue that I hadn't noticed (or noted in my post) is that ntpstat
showed "unsynchronised" instead of the normal:
synchronised to NTP server ( at stratum 3

Also, the ntpq output indicated in its own obtuse way that it wasn't
sync'd because there was no server with a * to the left of it.

No matter what I did, I couldn't get ntp to show "synchronised".  I
even would run ntpdate immediately followed by service ntp start and
it wouldn't sync.  And I confirmed ntpdate was indeed setting the
clock perfectly.  It made no sense!  I knew it was *not* a ntp config
error since it's config'd the same way as 20 other good boxes.

Anyhow, I started playing with kernel time sources and noticed this CPU
(Petnium D) supports HPET.

cat /sys/devices/system/clocksource/clocksource0/available_clocksource
tsc hpet acpi_pm

Current setting was tsc

So I changed it to hpet
echo hpet >> /sys/devices/system/clocksource/clocksource0/current_clocksource

Then ntpdate again

Then start up ntpd

BOOM!  Instantly ntpd syncs to a source and ntpstat shows sync'd!
WTF?  Oh well, at least it seems fixed.  Been 10 mins now and no time

To get grub2 to change the kernel line so my hpet change survives
reboot was another story... Grub2 looks nothing like grub!  Can you say

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