[ntp:questions] ntp too agressive on clock changes

David Woolley david at ex.djwhome.demon.invalid
Sat Apr 13 21:05:25 UTC 2013

[ Very long lines repaired. ]

website.reader3 at gmail.com wrote:
> I am running Ubuntu 12.04 LTS, running v4.2.6 ntp, but I am finding
+ that ntp is too agressive on clock changes. The loopstats show clock

The normal complaint is that ntpd is too slow at reacting to real 
changes in the clock.

+ changes up to 0.11+ secs which is way too high. I just set the ntp.conf

That doesn't sound right.  Normally ntpd will not step less than 0.128 

+ parameter "slewalways" to "yes", hoping that the maximum clock
+ adjustment will be in the neighborhood of 0.5 msec.

Setting slewalways is incompatible with using the kernel time 
discipline, which will result in ntpd making corrections every second in 
which it slews at +/- 500ppm, rather than making finer adjustments every 
clock tick.  Even then, that is only 0.0005 seconds maximum correction 
each second.
Something sounds very wrong about your system and/or you are 
misinterpreting  the diagnostics.  You need to provide a lot more 

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