On Tue, Sep 11, 2012 at 7:51 PM, Jan Steffens <jan.steffens@xxxxxxxxx> wrote: > On Tue, Sep 11, 2012 at 8:27 PM, Thomas Bächler <thomas@xxxxxxxxxxxxx> wrote: >> 2) When chrony is not running, systemd-timedated runs periodically to >> adjust the hardware clock for drift (AFAIK, not sure that is the job >> that timedated does). > > No. When chrony isn't running, the hwclock isn't getting adjusted at > all. The only thing systemd does on startup is warp the system clock > if and only if the RTC is running in localtime. > > systemd-timedated's job is to provide a DBus interface to change > system time and date settings: > SetTime, SetTimezone, SetLocalRTC (whether RTC is in localtime), > SetNTP (whether NTP is enabled) > It's used by gnome-control-center, at least. The SetNTP call uses the > ntp-units.d directory to select an implementation. Thank you for all the information - it seems that the key to this was that the RTC was too far out from correct time at boot - now that I manually set the RTC to correct time it comes up close to correct - and then chrony synchronises a few minutes after startup. At present tracking shows it is about 0.1 microsecs from NTP time: System time : 0.000000106 seconds fast of NTP time What I don't understand is why the hardware clock was not re-written with the correctly synchronised time previously, since chrony has been running every time I booted the system for ages? -- mike c
