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Re: Trim clock rate

AGC <agcarver+netbsd%acarver.net@localhost> writes:

> Is there a way to trim the clock rate in the kernel?  Watching ntpd run
> it seems to settle on a clock PPM offset of about -75.  I was thinking
> of testing a hypothesis but the first step is determining if that offset
> can be trimmed away so that ntpd's corrections hover around zero.

If you are running ntpd and it uses the kernel pll, there is basically
little point, because it's basically doing this already every increment.

man 2 ntp_adjtime

However, you could make the kernel code make the used rate adjustment be
-75 ppm plus what's commanded, and back out the -75 on read.  That is
only a few lines of kernel code, probably.

I'm happy to answer further questions (after you've read the man page,
RFC, and corresponding kernel code :-).

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