[time-nuts] chrony vs ntpd
hmurray at megapathdsl.net
Sat Oct 28 21:05:16 UTC 2017
I don't know much about chrony.
jimlux at earthlink.net said:
> Now that I have successfully connected my GPS receiver to my beagle and I'm
> getting pps ticks into the driver, etc. (thanks to info from several folks
> on this list!) the question arises of whether to use ntpd or chrony.
If you are running on Linux, you can get easy access to the PPS info via
$ cat /sys/devices/virtual/pps/pps0/assert
The stuff in front of the # is the time, the stuff after is the pulse count.
So you can setup something to collect the offset and see how well whatever
you are using is working.
If you want to test the non-PPS mode, you can setup your ntpd/chronyd to not
use it. The same measuring software will continue to collect data.
On most OSes, there are 2 ways to use the PPS. There is an API to read the
info. You can use that as a source of time to steer your clock with the same
sort of logic that you would use if you are getting time from a NTP server.
Usually it works better because of reduced jitter. Or, you can set a mode
bit in the kernel and it will make the adjustments while you sit back and
On Linux, the kernel mode is not available if your kernel is built with the
tickless scheduler. You have to build your own kernel...
These are my opinions. I hate spam.
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