[ntp:questions] NTP vs chrony comparison (Was: oscillations in ntp clock synchronization)

David L. Mills mills at udel.edu
Mon Jan 28 03:06:47 UTC 2008


It doesn't stop working; it just clamps whatever it gets to +-500 PPM as 
appropriate. If the intrinsic error is greater than 500 PPM, the loop 
will do what it can with the residual it can't correct showing as a 
systematic time ofset.


Danny Mayer wrote:
> David L. Mills wrote:
>>Unless the computer clock intrinsic frequency error is huge, the only 
>>time the 500-PPM kicks in is with a 100-ms step transient and poll 
>>interval 16 s. The loop still works if it hits the stops; it just can't 
>>drive the offset to zero.
> Yes, I found this out when my laptop stopped disciplined the clock and 
> was complaining about the frequency limits and I started digging into 
> the code to figure out why.
> Danny

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