[ntp:hackers] NTP software temperature compensation - ntp-dev-4.2.5p158
Danny Mayer
mayer at ntp.org
Mon Mar 9 04:31:39 UTC 2009
David R. Andersen wrote:
> I've spent some time and put together a software temperature
> compensation patch for ntpd.
>
> After some conversations with Mark Martinec (thanks!), I've basically
> replicated his compensation scheme in the recent development version.
> Further, I've added a temperature compensation update via the
> ntp_adjtime() system call for when that is available. I'm running the
> patched ntpd on a FreeBSD 7.0-RELEASE machine with the generic
> kernel. It also _runs_ on a Kubuntu 8.10 machine without
> ntp_adjtime(), but I haven't yet spent any time analyzing the
> performance of that machine.
>
> I've not spent a lot of time collecting data, but the performance of
> this patch seems pretty close to what Mark got. So far I am just
> using a linear compensation coefficient - but it is clear that a
> second-order coefficient will help a bit.
>
> The next step is to implement an adaptive controller to take care of
> broader temperature excursions and make tuning the thing less of a
> headache. I'll let you know how it goes.
>
> The patch is available at http://dx.eng.uiowa.edu/dave/ntptemp.php .
>
> Dave
Please open a bug report for this change so we can track it. It's going
to get lost among all of this mail.
Danny
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