[ntp:questions] ntp & system without a rtc
unruh at invalid.ca
Wed May 15 17:47:06 UTC 2013
On 2013-05-14, David Woolley <david at ex.djwhome.demon.invalid> wrote:
> Richard B. Gilbert wrote:
>> NTPD is NOT designed for fast convergence. From start up to get the
>> minutes correct, NTPD will need about thirty minutes! To get the best
>> time you are going to get, you will need to wait for about ten hours!
> Convergence to within 128ms should take a lot less than that. With
> iburst, I believe it should be less than one minute.
Since ntpd steps ( changes the rate by an infinite slope) if the time is
out by 128 ms, yes, convergence IS faster than that. ( however it has to
make sure that the clock really is out by that much and that takes a few
cycles of clock querrying).
For a ms accuracy your could expect a couple of hours. for 10
microsecond, about 10 hr.
More information about the questions