[ntp:questions] Re: ntpd Frequency (drift) Jumps

Charles Elliott elliott.ct at verizon.net
Sun Jul 2 15:53:42 UTC 2006

No, this motherboard does not seem to have any spread-spectrum functions; I 
looked thru the BIOS
setup screen and in the manual.  AFIK power-saving is disabled.  I do run 
Seti at Home on both CPUs, which can make the system seem sluggish at times. 
Also hyperthreading is enabled so
it appears as 2 CPUs.  I was looking thru the ntpd code and in at least one 
place they claim to
have made a fix that will work on single processor systems, but might not 
work on multiprocessor
systems.  I am considering moving it over to a Server 2003 single-cpu AMD 64 
machine to see if
the same problem appears.

The problem always seems to happen when the time offset is very small (< 5 
ms) and is about to change sign.  I wrote a Java routine to call ntpq every 
5 seconds and I have been watching it for the last half hour.  The offset 
just did change from -0.979 ms to 2.711 ms with no untoward result.

It always happens late in the evening or in the very early morning.  Verizon 
is making changes to its DSL system, and so there have been some outages and 
slow downs at these times.  Also the 50 to 100 and one 500 PPM frequency 
jumps are always accompanid by a large time adjustment (on the order of .180 

Do you have any more ideas?


"David J Taylor" <david-taylor at blueyonder.co.not-this-bit.nor-this-part.uk> 
wrote in message news:tROpg.94815$wl.28713 at text.news.blueyonder.co.uk...
> Charles Elliott wrote:
>> Yes, the Multi-Media timer option (-M) is set.
>> CHE
> Well, that leaves drivers taking too much time time at interrupt level 
> (PIO mode on the disks), or something else.  It could be bad hardware on 
> your motherboard.  Do you have any spread-spectrum or power-saving 
> functions set in your BIOS?
> Cheers,
> David

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