"David J Taylor" <david-tay...@blueyonder.not-this-part.nor-this.co.uk.invalid> writes:
>"nemo_outis" <a...@xyz.com> wrote in message [] >> I fail to see the value or relevance of "500ppm satisfies 98% of >> computer >> clocks" if some other number, perhaps 5000 ppm, could satisfy yet even >> more >> than 98% of computer clocks with no downside - as indeed seems to be the >> case! Chrony, whatever its other merits and demerits, is an "existence >> proof" for this proposition. >> >> Regards, >Oh, simply that have knowledge of how many computers were excluded at a >particular value of maximum drift might allow the NTP designer to make a >better judgement of just where to set that arbitrary 500ppm number. For >example, if 100ppm excluded 50% it would obviously be a poor choice, and >it 500ppm includes 99.999% of computers it could be an excellent choice. >As it is, in a community of end users perhaps one or two out of about a >hundred have reported problems with NTP as supplied, and it seems a shame >to exclude them if a small relaxation in the tolerance might allow them to >run NTP rather than them having the view "NTP doesn't work". >No chance of the limit being a command-line parameter, I suppose? So I have 9 clocks. The rates are -190, 19 , -106, -67,-200 -219, -115 -140 221 On reboot, the latter changed from 221 to 215 (Which took ntp about 6 hours to recover from) The clock scaling in linux seems to suffered a real problem in the past year or two, so that the rate from one reboot to the next can change by 50PPM, which then takes ntp a long time to recover from. two years ago those same clocks, running earlier kernels, had rates of 5 -17 45 27 23 100 101 -10 8 -39 39 25. It will not take much more degredation for the clocks to surpass the 500PPM limit. And this is not due to any change in the hardware. It seems to be kernel software and the scaling calibration being performed at bootup. _______________________________________________ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
