Rasp Pi at +/- 1 us from GPS
hmurray at megapathdsl.net
Sun Nov 26 21:44:18 UTC 2017
devel at ntpsec.org said:
> - pps-client installed as expected. One gets the Stretch source and
> compiles the kernel as part of that.
It would be interesting to poke around in pps-client to see what it actually
There are two ways to use PPS. One is to to capture the data and then feed
the offset into a normal algorithm like ntpd uses. The other is to set a
mode bit so the kernel does all the work.
The latter doesn't work with the NO_HZ scheduling option in the kernel. Most
distros ship a kernel with that option enabled to save power. Rebuilding the
kernel is a strong hint that they want to use the kernel mode. If that's the
case, you can use ntpd to do the same thing. It's a flag bit to the PPS
It would be interesting to compare whatever pps-client does with what ntpd
does (same kernel) with and without that flag.
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