[ntp:questions] Re: Windows - Seven Days Later

Richard B. Gilbert rgilbert88 at comcast.net
Thu Oct 14 01:52:50 UTC 2004

Jerry Baker wrote:

> David Woolley wrote:
>> You seem to be have been taking a very hostile attitude to ntpd all 
>> along,
>> but you have been continually changing the goalposts and dribbling in
>> critical pieces of information.  What, for example, happened to your
>> original 2.6s step problem?
> I don't think it's hostile. NTP, after all, is a software package and 
> I don't think software can experience "hostility." The reason I 
> suspect NTP is because most of the people involved with NTP seem to be 
> pretty hostile towards Windows in general, and completely unwilling to 
> even entertain the notion of exploring possible work-arounds for this 
> issue. Most responses are something like, "uh, well, I don't have 
> Windows but I think it works like this."
>> Looking at your MRTG graphs, you are not getting uni-directional clock
>> steps, but rather paired forward and backward steps, which are slightly
>> confused because the clock never appears stable enough for ntpd to
>> establish a large poll interval and long time constant, so ntpd has
>> partially corrected the step in one direction, before the counter step
>> (note, as I pointed out before, the phase errors are the cause of the
>> frequency changes, not the other way round).  ntpd is doing its best
>> with low quality time data that keeps stepping backwards and forwards
>> by what looks like a clock tick.
> The poll interval has remained 1024s for two weeks.
>> How are you instrumenting the SNTP client?  In any case, most SNTP 
>> clients
>> use relatively long poll intervals, which will tend to low pass filter
>> out the forwards and backwards steps in the time measurment.  You may be
>> able to make ntpd filter them out by using a longer minpoll, but I can't
>> guarantee that that won't result in instability or a failure of the loop
>> to initally capture.
> I set up an SNTP client (D4) to poll every 15 minutes. When I do that 
> it shows a regular correction of about 5ms.
>> Of course, if you really think that ntpd is broken on NT, the source is
>> published and you can debug it yourself.  The NT specific code ought to
>> be fairly easy to find.
> I hope your mechanic never says, "well, I'm not going to fix your car, 
> but if you think something is wrong there's all the parts."  

The difference is that your mechanic will hand you a big bill for fixing 
whatever is wrong!  I believe that ntp is a volunteer effort on the part 
of all concerned.  I think most of the developers use some version of 
Unix  and don't use Windows unless forced to by the requirements of 
their regular jobs.

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