[ntp:questions] Re: ntp servers reporting leap second erroneously?

Terje Mathisen terje.mathisen at hda.hydro.com
Tue Oct 25 09:12:07 UTC 2005


David J Taylor wrote:
> Hal Murray wrote:
> 
>>>As I've reported earlier on this news group even the Windows w32time
>>>service is capable to slew the Windows system clock at UTC midnight
>>>to compensate the leap second offset in just a few seconds.
>>
>>How fast does Windows normally slew?  I was expecting it to be 500
>>ppm which would take a long time to slew a whole second.
> 
> 
> IIRC from the earlier posting W32time actually doubled the clock speed 
> (SetSystemTimeAdjustment) for two seconds.  Is that how others read it?

Yes, that seems like the obvious way to handle it.

ntpd must calculate this as an extra adjustment on top of the current
drift value, so to avoid messing up clock stability.

You can of course discuss how fast this adjustment should be applied,
but my thinking is that such an exceptional situation should be handled
quickly.

Most people will be able to accep a timing glitch happening around the
exact leap second epoch. I.e. I think 2 seconds to get back in sync is fine.

Terje

-- 
- <Terje.Mathisen at hda.hydro.com>
"almost all programming can be viewed as an exercise in caching"




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