[RndTbl] system loses time
grdetil at scrc.umanitoba.ca
Tue Dec 11 15:09:13 CST 2012
On 12/11/2012 02:35 PM, Trevor Cordes wrote:
> 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 (220.127.116.11) 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
Rather than changing the grub2 configuration, I think you can make that
clocksource change permanent by adding the following line to
devices.system.clocksource.clocksource0.current_clocksource = "hpet"
There's a similar issue, apparently, under Xen, as described in this post:
Gilles R. Detillieux E-mail:<grdetil at scrc.umanitoba.ca>
Spinal Cord Research Centre WWW: http://www.scrc.umanitoba.ca/
Dept. Physiology, U. of Manitoba Winnipeg, MB R3E 0J9 (Canada)
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