[Sussex] NTP Weirdness

[Steve Dobson]

John, et al

On Wed, 2008-04-23 at 18:29 +0100, John D. wrote:
> On Wednesday 23 April 2008 14:11:03 Michael-John Turner wrote:
> > On Wed, Apr 23, 2008 at 12:44:45PM +0100, Steve Dobson wrote:
> > > The system is a duel Pentium 4 2.6GHz running Debian (Etch) 4.0.  I've
> > > installed ntp to keep the clock up to date but it drifts badly, racing
> > > the clock ahead of real time by tens of minutes per day.
> >
> > To be honest, I've only ever seen NTP weirdness with a Sun Ultra 2 that had
> > a faulty RTC - the time would fluctuate badly and it didn't hold time
> > between reboots. Switching to OpenNTPD helped a bit, but it was ultimately
> > a hardware issue.
> >
> > Does your system perhaps have hyperthreading enabled? I know that it can
> > cause havoc with NTPD.
> Well Steve isn't the only one that has some "debian related" weirdness in 
> respect of this.
> 
> I'm runnin "Sidux", which is debian SID. I get it slightly differently though. 
> It doesn't matter which online time server I select it keeps setting my clock 
> 10 minutes slow.
> 
> I tend to notice it after I've run the "smxi" updating script. It doesn't 
> matter how often I change the region/area to reflect London, it seems to 
> default it back to Guernsey for UK time.
> 
> I don't know if this is exactly the same problem that Steve is experiencing, 
> but I certainly don't have any hyper-threading, because it's running on a 2 
> gig pentium 4 so I'm thinking that if it is a common problem it could 
> possibly be debian related.
> 
> Apart from that, I have no idea about the possible technicalities too look 
> at - as I still qualify (and probably will always) as "nugget"! :D

John: Is your system overclocked?

All:  Yesterday afternoon I disabled NTP on the box and reset the time.
This morning (less than 12 hours later) the clock was ~10 minutes fast.
As the system clock is run of the software timer interrupt my thoughts
are now turning to overclocking as being the prim suspect.

Does this make sense to others?  I don't really want to go the the
trouble of pulling the heavy server out of the rack in order check the
jumpers on the motherboard if I'm barking up the wrong tree.

Steve