On Fri, Jun 29, 2012 at 8:40 PM, Daniel Norton <[email protected]> wrote: > From http://www.ntp.org/ntpfaq/NTP-s-algo-real.htm#AEN2499 > > 5.3.4. What happens during a Leap Second? > > The theory of leap seconds in explained in Q: 2.4.. In reality there are two > cases to consider: > > If the operating system implements the kernel discipline described > in Section 5.2, ntpd will announce insertion and deletion of leap seconds to > the kernel. The kernel will handle the leap seconds without further action > necessary.
Although exactly how it's handled is platform-defined. One can imagine simply stepping the clock, pausing the system for a second, or more subtle schemes that try to ensure always-increasing clock readings. I'm curious if any don't simply step the clock. > If the operating system does not implement the kernel discipline, the clock > will show an error of one second relative to NTP's time immediate after the > leap second. The situation will be handled just like an unexpected change of > time: The operating system will continue with the wrong time for some time, > but eventually ntpd will step the time. Effectively this will cause the > correction for leap seconds to be applied too late. NAK on that FAQ. Well, assuming recent ntpd that is. I'm not sure when it changed, but modern ntpd steps the clock back if not using the kernel loop discipline. That FAQ hasn't been maintained in many years and is increasingly unhelpful. I'd like to see it updated simply to say it's out of date and shouldn't be relied upon. The intended replacement is the http://support.ntp.org collection of [t]wikis. Cheers, Dave Hart _______________________________________________ pool mailing list [email protected] http://lists.ntp.org/listinfo/pool
