NTP time slews continuously - why?

NTP time slews continuously - why?

Post by A. Ian Vogelesan » Mon, 28 Oct 1996 03:00:00



Kernel 2.0.10 (but has been occurring for a _long_ time ...)
Running NTP, with time being set directly from a WWV clock receiver.

Time continuously slews; every few minutes NTP makes a
step adjustment to get it back into sync.  Unlikely to
be hardware, because it happens exactly the same on
a P90 and a P6-200 SMP.

Ideas?

 
 
 

NTP time slews continuously - why?

Post by Bob Hau » Tue, 29 Oct 1996 04:00:00




Quote:> Kernel 2.0.10 (but has been occurring for a _long_ time ...)
> Running NTP, with time being set directly from a WWV clock receiver.

> Time continuously slews; every few minutes NTP makes a
> step adjustment to get it back into sync.  Unlikely to
> be hardware, because it happens exactly the same on
> a P90 and a P6-200 SMP.

Use "tickadj" to tweak the kernel time increment.  I had this exact
problem (without a radio clock).  Basically, the clock oscillator
on the motherboard was too far off for ntp to discipline it.

I put "tickadj 9997" in the boot script on that machine and it works
fine now.  I actually have several PC's here where the motherboard
clock is off by more than the allowed 300 ppm.  Newer motherboards
actually seem to be worse than older ones in this respect.

This was with a 1.2.13 kernel with the pll patch.  Don't know if
anything changed WRT timekeeping in 2.0, but if it did that could
be causing you grief as well.

---

 Wasatch Communications Group               http://www.wasatch.com

 
 
 

1. ntp always resets clock instead of slewing clock

Hello,

I'm running ntpd 4.1.1b, Debian sid, currently using dial-up. I start and
stop the /etc/init.d/ntp-simple daemon with scripts in /etc/ppp/ip-up.d/
and /etc/ppp/ip-down.d/ respectively.

Curiously 'ntp-simple' always resets the clock instead of slewing it. I'm
curious as to why.

Jun 14 13:39:52 mobile pppd[1673]: Script /etc/ppp/ip-up finished (pid 1681), status = 0x0

Jun 14 13:39:52 mobile ntpd[1832]: signal_no_reset: signal 13 had flags 4000000
Jun 14 13:39:52 mobile ntpd[1832]: precision = 35 usec
Jun 14 13:39:52 mobile ntpd[1832]: kernel time discipline status 0040
Jun 14 13:39:52 mobile ntpd[1832]: frequency initialized 70.305 from /var/lib/ntp/ntp.drift
Jun 14 13:39:52 mobile ntpd[1833]: signal_no_reset: signal 17 had flags 4000000
Jun 14 13:44:18 mobile ntpd[1832]: time reset 3.689185 s
Jun 14 13:44:18 mobile ntpd[1832]: kernel time discipline status change 41
Jun 14 13:44:18 mobile ntpd[1832]: synchronisation lost

The logs always show 'time reset xxxxxxx s' followed by synchronisation
lost.

Is this normal? Is there anything I can do to get the clock to slew
instead of resetting? Should I even be concerned?

--
Ciao,
CRH 8^)>

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