Kernel slew/PLL (from IRC)

Gary E. Miller gem at
Wed Sep 28 19:50:59 UTC 2016

Yo Hal!

On Wed, 28 Sep 2016 02:06:18 -0700
Hal Murray <hmurray at> wrote:

> I think two things are getting confused.  One is the ability to slew
> the clock.  The other is a PLL to automate tracking a PPS.

I am unaware of any PLL directly tracking PPS in ntpd or mainline Linux
kernel..  The PPS is averaged by ntpd over the poll interval.  Then the
raw data is used in the main ntpd/kernel PLL.

> There is a PLL kernel option to track a PPS.  It's not compiled into
> most Linux kernels.

Thus a distraction to our discussion.

Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
	gem at  Tel:+1 541 382 8588
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