On Tue, Sep 11, 2012 at 7:51 PM, Jan Steffens <jan.steffens@gmail.com> wrote:
On Tue, Sep 11, 2012 at 8:27 PM, Thomas Bächler <thomas@archlinux.org> 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