[ntp:questions] Frequency Offset

David J Taylor david-taylor at blueyonder.co.uk.invalid
Sun Feb 26 08:51:06 UTC 2012


"Richard B. Gilbert" <rgilbert88 at comcast.net> wrote in message 
news:X_ednYrcXr9Hz9TSnZ2dnUVZ_rCdnZ2d at giganews.com...
[]
> Get ready for a shock.  NTPD needs thirty minutes or more to get a 
> reasonable facsimile of the correct time.  To get the microseconds 
> right, NTPD needs more like ten hours!  It's not a very good fit for 
> running 9AM to 5PM.  You set it running and leave it running 24x7!

I just happened to check a warm NTP restart on a stratum-1 Windows XP 
server.  The offset was stable within 30 minutes, and the jitter had 
settled at a steady level of 2.5 microseconds after about 35 minutes.

On a Windows-7/32 stratum-1 server, the offset reached stability after 7 
minutes, and the jitter reached a stable value (20 microseconds) after 
less than 30 minutes.

On a Windows-7/64 stratum-1 server, the offset reached stability after 4 
minutes, and the jitter reached a stable value (30 microseconds) after 
less than 20 minutes.

Both Win-7 servers have NTPD_USE_INTERP_DANGEROUS=1 set, as it produce 
better results sometime in the past.

Cheers,
David 



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