Hi all, I wrote about connecting to close by server is better but I was still unsatisfied with the way ntpd reacted to small network glitches when using reasonable poll values.
The silly thing is I knew I have a decent oscillator and that ntpd shouldn't fool around with my clock that much with its supposedly fancy "averaging" algorithms that are trying to figure out the real time it is. I was even more deceived by ntpd after spending a few hours searching the docs and the mailing lists to find out that there seems to be no way of configuring limits on how much ntpd fools with the frequency of my clock. Tell me I am a fool if I missed it in the docs ;-) Anyway, I am quite satisfied with the hack I came up with, see: http://www.pool.ntp.org/scores/207.236.226.149 It seems now clear that my server keeps time between 0 and +10 ms viewed from the pool monitoring system. You could draw a nice average line showing that by removing the peaks caused by network glitches. Hack: By trial and error, I found out the min and max frequency I want my clock to have (mind you ntpd) and I just overwrite the value set by ntpd if needed every minute with the script below. Try it out if you are tired of ntpd typical roller-coaster rides ;-) Typical example of what I used to experiment before (at the time of this writing): http://www.pool.ntp.org/scores/147.231.100.5 So, the basic idea is that I don't care if ntpd thinks I am 90 ms ahead or behind, I know I can't be more than 5 ms ahead or behind and my system react accordingly thus keeping more accurate time. #!/bin/sh # Note that values are system dependant !!!! # 251616 = 3.839 in ntpq -c rv # 269120 = 4.106 # 280448 = 4.279 # 288544 = 4.403 let LOWLIMIT=280448 let HILIMIT=287520 let FREQ=`adjtimex -p | grep frequency | cut -d ":" -f 2 | cut -c 2-` if [ ${FREQ} -gt ${HILIMIT} ] then adjtimex -f ${HILIMIT} fi if [ ${FREQ} -lt ${LOWLIMIT} ] then adjtimex -f ${LOWLIMIT} fi Louis http://blogtech.oc9.com http://www.pool.ntp.org/scores/207.236.226.149 _______________________________________________ timekeepers mailing list [email protected] https://fortytwo.ch/mailman/cgi-bin/listinfo/timekeepers
