[ntp:questions] Very large offset and jitter values after reboot

Richard B. Gilbert rgilbert88 at comcast.net
Sun Aug 24 19:19:53 UTC 2008

Nicola Berndt wrote:
> Hello,
> I have now successfully set up my machine to use a usb-gpd-mouse to set 
> the time. Strangely every time I reboot I get results like this, wich 
> settle down after a (not so short) while:
>      remote           refid      st t when poll reach   delay   offset  
> jitter
> ==============================================================================
>  GPS_NMEA(0)     .GPS.            0 l    9   64   37    0.000  -580.75 
> 3965.19
> The problem is, that this takes rather long and the computer's job 
> actually is, to provide exact time outdoors right after booting..
> I already tried what would happen if I did a 'hwclock --systohc' once 
> things are settled, but with no luck. My driftfile btw. says -35.666 - 
> looks good to me - and I am very worried about the huge jitter...
> Any ideas for me, anyone?
> Thx and regards,
> ../nico berndt

1.  Don't reboot!  My Windows, Linux, Solaris, and OpenVMS systems will 
all run until the power goes off for longer than the run time of my UPS.

2.  Start ntpd with the "-g" switch.  The -g switch tells it to get and 
set the correct time.  Following startup, ntpd will discipline the clock 
in the usual way.  It may take a relatively long time, around thirty 
minutes, to settle into really tight synchronization.

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