"Unruh" <unruh-s...@physics.ubc.ca> wrote in message news:o48hm.41192$ph1.17...@edtnps82... > "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. >
Sometimes "complex" problems can have simple solutions. I had the same issue a couple years ago with multiple computers. I bought a box of button batteries and changed every one I could find. My hardware clocks improved at least on the order that you say yours degraded, perhaps more. _______________________________________________ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
