[ntp:questions] Re: ntp servers reporting leap second erroneously?

Martin Burnicki martin.burnicki at meinberg.de
Wed Oct 26 11:04:54 UTC 2005


David L. Mills wrote:
> Martin,
> As a practical matter, the poll intervals and for that matter the
> seconds interrupt used by the reference clock drivers are not
> synchronized between systems, only the system time. In principal it
> would be possible for each client to calculate how many ticks to the
> appointed event, but not simple at all in the context of the current NTP
> engineering model.

Please see my proposal in my other reply. I think the timer ticks are on a
level which is too low to support several operating systems which don't
have kernel PLL.

> It may in fact be easier to have a separate process whose only mission
> to step the clock back one second at a designated time and activated by
> a cron job or whatever the equivalent in Windows. Don't do a slew at
> this point; that would drive the NTP clock discipline nuts.

The leap second is an exception, so it should be handled as an exception. If
an additional offset is applied in adj_host_clock() for a specific
interval, just to account for the leap second, then the variables of the
clock discipline algorithm should not be touched at all.

Martin Burnicki

Meinberg Funkuhren
Bad Pyrmont

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