[ntp:questions] Time reset

David Woolley david at ex.djwhome.demon.co.uk.invalid
Sat May 3 09:09:47 UTC 2008


David J Taylor wrote:
> Unruh wrote:
> []
>> But ntp arguably should handle jumps in time or frequency faster than
>> the hours or days it takes now.
> 
> Why?  A jump (to me) implies an error in the hardware.  Who is to say that 
> it's a one-off jump, or that it might not occur again in a few seconds, 
> minutes ot hours?  Should it not be the hardware which is corrected, not 
> NTP?

I think one has to distinguish between jumps in time and in frequency. 
The naive test uses a jump in time, which is not a real life situation 
for serviceable equipment.  However, jumps in frequency are quite 
possible as the result of rapid temperature changes, and as the results 
of aging processes in the electronics.

Unruh's main issues with ntpd is actually its response to frequency 
transients, not its response to phase transients, and he is diluting his 
case by introducing phase transients.  The one exception to this is the 
ntpd's poor response to the startup phase transient.




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