[ntp:questions] Bug 1700 - Clock drifts excessively at pollinglevels above 256.

Mischanko, Edward T Edward.Mischanko at arcelormittal.com
Sun Apr 24 03:39:44 UTC 2011

Your question is a very good one that I don't know the answer to.  I
have observed this behavoir while actually watching NTP Time Server
Monitor by Meinberg, live.  I didn't anticipate any power saving
features as being active.  I have seen a correction in the behavior by
changing the PLL and FLL gains, as noted.  I haven't specifially looked
for this problem in other ports, only Windows and only on systems
without a referrence clock.

-----Original Message-----
From: questions-bounces+edward.mischanko=arcelormittal.com at lists.ntp.org
[mailto:questions-bounces+edward.mischanko=arcelormittal.com at lists.ntp.o
rg] On Behalf Of unruh
Sent: Saturday, April 23, 2011 1:20 PM
To: questions at lists.ntp.org
Subject: Re: [ntp:questions] Bug 1700 - Clock drifts excessively at
pollinglevels above 256.

On 2011-04-22, Mischanko, Edward T <Edward.Mischanko at arcelormittal.com>
> 256.
> My system clock drifts excessively when polling above 256 in a Windows
> environment, as much as 5 ms or more.  I have made changes to
> .../ntpd/ntp_loopfilter.c CLOCK_PLL, CLOCK_FLL, CLOCK_LIMIT, and
> CLOCK_PGATE to address this problem.  I realize the changes I have
> are global in nature and really only need changes in the Windows port.
> I would welcome a patch to the Windows port to accomplish these
> or any other changes that accomplish the 1 ms stability I have now
> achieved.  I hope Dr. Mills will have constructive comments on this
> problem and proposed solutions.

Does your system cpu use powersaving cpu frequency changes? Is it a
virtual Windows machine?

> */

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