[ntp:questions] ntpd on embedded risc

Rob nomail at example.com
Wed Feb 18 17:32:47 UTC 2009

Unruh <unruh-spam at physics.ubc.ca> wrote:
> But a snapshot taken before the system has settled down to its long term
> behaviour is especially useless. The way ntp works is that intially it
> takes a while to settle down to its long term behaviour. With PPS control
> it usually settles down to usec offset but it takes of order of 10 hours to
> do so. Thus snapshots taken long before that are especially useless. If
> after 10 hours the system still has msec offsets from a PPS then there is
> something seriously wrong.

He is not using a PPS in the sense that you are talking about.
He uses the PPS support in gpsd which is written in user space and
will settle to around 10us on a fast system that is not overloaded.
On a slow embedded board it may be different, I have no experience
with running gpsd on those.

More information about the questions mailing list