Rename PRV_Initialise() to PRV_StartHelper() and add a new
initialisation function, which just sets the helper fd to -1. Move
the initialision/finalisation calls from the system drivers to main.c.
If privops is not included in the build, define empty macros for the
function names, so their calls don't have to be wrapped in #ifdefs.
When the rtcsync directive is specified in the chronyd config file,
chronyd will update the RTC via settimeofday() every 60 minutes if
the system time is synchronised to NTP.
Timeout ID of zero can be now safely used to indicate that the timer is
not running. Remove the extra timer_running variables that were
necessary to track that.
When a large spike occurs in offset_sd the drift removal interval can be
set to an excessively long time, although what ever event caused the
perturbation has passed. At the next set_sync_status() we now compare
the expected drift removal interval with that currently in effect. If
they are significantly different, the current timer is cancelled and new
cycle started using the new drift removal interval.
Adds option -P to chronyd on MacOS X which can be used to enable the
thread time constraint scheduling policy. This near real-time scheduling
policy removes a 1usec bias from the 'System time' offset.
Adjust the drift removal interval based on the observed offset_sd.
A newly calculated interval goes into effect after the current drift
removal has completed. When offset_sd is high, the interval is increased
resulting in fewer wakeups to adjust the drift offset. At lower values
of offset_sd the drift removal adjustment interval is pinned to 0.5
seconds. The predicted error applied at the start of an adjustment is
based on the remaining time of the drift removal that is currently in
effect. Default drift removal adjustment interval is 4.0 seconds (was
1.0). If not synchronised set interval to maximum of default interval
and current interval. Clamp elapsed drift removal time to
[0, current_drift_removal_interval] to cover clock stepping.
In drivers with periodic drift removal include in the adjustment also a
prediction of the error gained in half of the interval to move the mean
offset of the clock closer to zero. E.g. offset of a stable clock
drifting by 10 ppm should now be closer to 0 +/- 5 microseconds instead
of 5 +/- 5 microseconds.
The darwin kernel implementation of adjtime() does not require the
adjustment to be aligned to a tickadj boundary, and we can apply
adjustments to the nearest microsecond. Rounding is accounted for by
adding any rounding errors back into the offset.
