| Re: [chrony-dev] SOCK refclock system time resolution |
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On Mon, Sep 11, 2023 at 10:29:30 +0200, Miroslav Lichvar wrote:
> On Fri, Sep 08, 2023 at 11:21:08AM -0400, Josef 'Jeff' Sipek wrote:
> > I'm playing with feeding data to the SOCK refclock with GPS time myself
> > (without using gpsd, etc.). I saw that the samples contain the host/system
> > timestamp as a struct timeval. I changed it to allow nanosecond time of
> > measurements but before I try to polish it and send it for inclusion, I
> > wanted to check if there would there be interest in that? The current diff
> > is below, but it needs a bit more cleanup and testing.
>
> That timestamp doesn't need much resolution. It just says when the
> offset (in double format) was captured. Milliseconds would be fine.
Ok. I just saw that the code uses that the timestamp and the offset to
calculate the time (for non-PPS sources) and it seemed desirable to get more
than microsecond resolution for that before it gets fed into RCL_AddSample.
In other words, this timestamp indirectly affects the resolution of the
sample fed in.
> The code was written when chrony was still internally using timeval.
> If it was written today, timespec would be the obvious choice,
Makes sense.
> but
> switching now I think would just create unnecessary work for the
> applications and more code to maintain.
The way I changed the code, it handles 3 variants: 32-bit timeval, 64-bit
timeval, and timespec (fixed at 2*64 bits). So, no application changes are
required and the extra code is in chrony.
Jeff.
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