[ntp:questions] Re: Clock jumps 1 second every 11 minutes (Linux+SMP+NTP)

Nathan Parker google.20.nathanpll at spamgourmet.com
Thu Aug 28 16:20:06 UTC 2003


vek at station02.ohout.pharmapartners.nl (Villy Kruse) wrote in message news:<slrnbkm6c1.42j.vek at station02.ohout.pharmapartners.nl>...
>
> Supposedly the kernel should set the RTC clock from the system clock
> every 11 minutes, if the kernel finds out a ntp server is active.  
> The reason for that is that a NTP controlled system clock would be
> more accurate than the RTC clock, and regularly resetting it will
> increase the likelyhood that it is reasonably correct next time the
> system is booted, which is normally the only time the value of the
> RTC clock matters.
> 
> 
> Villy

That makes sense to me, but it doesn't make sense that updating the
RTC would screw up my system clock.  Any idea why it does this?

An Update:  By manually adjusting /etc/ntp/drift, I eventually got NTP
to stay sync'ed to an external server for many hours at a time.   BUT,
it still jumps 1 FULL SECOND a few times a day (randomly), and then
resets the time after complaining that it lost its sync. Does this
have to do with how NTP control the slewing? Or are there other
functions in the Linux kernel that could be to  blame for this time
jump?

 -- Nathan Parker



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