| Re: [chrony-dev] [PATCH] MacOS X - Dynamic drift removal interval |
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On Thu, Aug 13, 2015 at 08:18:30PM +1200, Bryan Christianson wrote:
>
> > On 11/08/2015, at 11:56 pm, Miroslav Lichvar <mlichvar@xxxxxxxxxx> wrote:
> >
> > BTW, when experimenting with multiple sources and longer drift removal
> > intervals I think it might be useful to rework the
> > get_offset_correction() function to not stop and restart the currently
> > running adjustment, but only read the remaining offset with
> > adjtime(NULL, &tv), so NTP measurements from sources other then the
> > selected peer are not restarting the drift removal. This would also
> > reduce the number of adjtime() calls, especially on a NTP server.
> >
>
> On MacOS, adjtime(NULL, &rem) is not supported.
I see.
> To implement the above, requires 2 adjtime() calls, one to stop it and one to restart it so I don't think there are any real benefits in doing this.
I think with the new predicted drift error added to the adjtime()
offset there could be some difference on servers. As for each client
request there is one or more get_offset_correction() calls, the
average offset of the clock might be worse than it would be with only
drift removal updates restarting the adjustment.
Maybe the interval used in the calculation of predicted_error should
include the interval since the last drift removal timeout? That would make
it independent from other restarts of the adjustment.
--
Miroslav Lichvar
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