[ntp:questions] Falseticker determination
agcarver+ntp at acarver.net
Thu Apr 5 04:37:25 UTC 2012
On 4/4/2012 18:52, E-Mail Sent to this address will be added to the
> Dave Hart wrote:
>> A C<agcarver+ntp at acarver.net> wrote:
>>> Where in the code of 4.2.7p270 is the determination that
>>> a peer is a falseticker? I'm looking through ntp_proto.c
>>> but I don't think I'm fully grasping how the determination
>>> is made and the peer marked.
>>> I want to put some debug lines in the area of the code
>>> where the falseticker is determined so I can figure out
>>> what conditions are causing the PPS to be marked as a
>>> false ticker.
>> Line 2519 of ntp_proto.c (in clock_select):
>> peer->new_status = CTL_PST_SEL_SANE;
>> All survivors to that point in the code get the x, fleetingly. Those
>> that keep it fail to survive to line 2688:
>> peers[i].peer->new_status = CTL_PST_SEL_SELCAND;
> I would have thought 2835 - 2855 might be where he would
> want to take a closer look.
Well that was a fun exercise. The end result is that the PPS is no
longer a false ticker and I don't need a prefer peer either. :)
Believe it or not, it's actually working better this way. For starters,
the offset is staying within +/- 10 us of the PPS pulse. Additionally,
allowing the system to select the rest of the clocks using the normal
clock selection instead of a prefer peer has actually quieted the
sys_fuzz messages. Usually I was seeing a sys_fuzz message perhaps once
every couple minutes. Now I see one maybe once in a few hours or more.
Plus if any of the peers explodes for whatever reason it doesn't wipe
out my clock because the averaged time doesn't move much.
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