| Re: [chrony-dev] [GIT] chrony/chrony.git annotated tag, 1.27-pre1, created. 1.27-pre1 |
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On Mon, Mar 12, 2012 at 08:26:42AM -0700, Bill Unruh wrote:
> Surely what is reported from the refclock is the time stamp, not the offset.
> It is chrony which is stripping off the seconds to give an offset.
> Ie, the raw offset should be the difference between the "true time" as set by
> the refclock, and the system time. If the refclock does not know what second
> it is (PPS) then that offset should be something like t-int(t+.5) not simply
> t-int(t).
The PPS refclock driver sets the offset passed to the common refclock
routine to ts.tv_nsec / 1e9 where ts is the timestamp fetched from
kernel via PPSAPI. But it's not really an offset as it doesn't know
yet from which timestamp it should be substracted.
The code which prints the offset could shift it according to the PPS
rate though.
> Note that this is the way it used to be AFAIK (chrony 1.24 with the shm
> driver)-- you would get both pos and neg offsets in the raw time.
The SHM refclock is not a PPS refclock, the offset value coming from the
driver is a real offset.
--
Miroslav Lichvar
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