[ntp:questions] simple nt.conf cases for ntp-client
David Woolley
david at ex.djwhome.demon.invalid
Fri Jan 24 19:06:33 UTC 2014
On 24/01/14 17:42, William Unruh wrote:
> Does it use the time from that one, or some sort of "average"? Since the
> queries of the different servers occur at different times (separated by
> about and hour, given the initial filter at poll 10) how does it take the averagei
> if it uses the average?
If there is a prefer peer and it survives, it uses that one, otherwise
as per clock_combine in ntp_proto.c, i.e. weighted by synchronisation
distance (which grows with time).
8,000 seconds is more like two hours. If that poll interval is being
used, it is assumed that time errors don't vary much over period
several times that.
The weighting may change between versions. This is 4.2.7p333.
y = z = 0;
for (i = 0; i < npeers; i++) {
x = 1. / peers[i].synch;
y += x;
z += x * peers[i].peer->offset;
}
sys_offset = z / y;
Jitter code removed.
More information about the questions
mailing list