[time-nuts] NTP's discontinuity (it isn't) (was Re: leapseconds, converting between GPS time (week, second) and UTC

[Peter Laws]

On Wed, Jan 16, 2019 at 2:01 AM Fiorenzo Cattaneo <fio at cattaneo.us> wrote:

> headache to worry about (remember all the bugs that pop up even when
> we switch in and out of DST, like applications crashing because NTP
> applies the 1 hour change in a discontinous manner


NTP does no such thing.  NTP's timescale is in 136-year eras that
begin on 1900-01-01 (meaning that it rolls in 2036, which will make an
interesting dry run for the UNIX epoch rollover in 2038).  As the
author says, ``the NTP timescale [...] knows nothing about days, years
or centuries, only the seconds since the beginning of the current era
which began on 1 January 1900. '' (http://doc.ntp.org/4.1.2/leap.htm).

Any DST adjustment is done by the OS where NTP is running.  NTP does
know leap seconds even if the OS where the daemon is running gets
confused.  Always fun to watch the clock strike 23:59:60.


-- 
Peter Laws | N5UWY | plaws plaws net | Travel by Train!