On 2011-04-18, Chris Albertson <[email protected]> wrote: > On Sun, Apr 17, 2011 at 7:58 PM, C BlacK <[email protected]> wrote: >> Why would it take ntpd ten hours to achieve its accuracy? ?Can this be >> explained in laymans terms and >> mathematically > > In very simple terms.... > > Ignore NTP and computers and think about an old mechanical clock. > Lets say you wanted to adjust the rate of the clock to one part in > 10,000. But the hands can only be read to the nearest one second but > you are lucky to have an atomic clock nearby. In theory it would take > you 10,000 seconds to know if you adjusted the clock correctly. In > other words it would take 10,000 seconds for the clock to gain or > loose one second relative to your standard. > > NTP works kind of like that. It uses a set of reference clocks and > watches the rate of your local clock relative to the reference > clock(s) and depending on details it make time some time
Nice analogy. If only chrony did not demonstrate that using exactly the same time interchange with an accurate clock, the computer can achieve usec accuracy within less than an hour. Ie, your analogy simply does not hold as a general statement. > > _______________________________________________ questions mailing list [email protected] http://lists.ntp.org/listinfo/questions
