[ntp:questions] ntp too agressive on clock changes

website.reader3 at gmail.com website.reader3 at gmail.com
Sat Apr 13 19:43:04 UTC 2013

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 changes up to 0.11+ secs which is way too high.  I just set the ntp.conf parameter "slewalways" to "yes", hoping that the maximum clock adjustment will be in the neighborhood of 0.5 msec.

In the meantime, I am trying to replace the std CMOS clock with a +/- 2ppm precision oscillator so I don't have big startup time deltas (I have seen 2 secs at times).  Yes, I know a precision pps board using a GPS disciplined clock is the best way to go here, but I have to make due with an accurate RTC and ntp.

Are there any other things I need to set, so ntp won't adjust the sys clock with steps greater than 0.5 msec ?  I run a program during the day which does hundreds of thousands of time stamps, and found that it had glitches due to clock changes being more than it could tolerate.

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