[ntp:questions] change between 4.2.8p6 and 4.2.8p10 release - SHM
MAYER Hans
Hans.Mayer at iiasa.ac.at
Tue Mar 28 09:59:08 UTC 2017
Dear All,
My environment a GPS disciplined NTP server running on armv7l GNU/Linux with kernel 3.4.108+
gpsd version 3.15
This is the relevant part of the configuration
# Enabling PPS/ATOM support
server 127.127.22.0 minpoll 4 maxpoll 4
fudge 127.127.22.0 refid PPS time1 0.000001
fudge 127.127.22.0 flag3 1 flag4 1 # enable kernel PLL/FLL clock discipline and clockstats
# gpsd shared memory clock
server 127.127.28.0 minpoll 4 maxpoll 4 prefer # PPS requires at least one preferred peer
fudge 127.127.28.0 refid GPS
fudge 127.127.28.0 time1 +0.1565 flag4 1 # coarse processing delay offset
Now I tried to update my NTP server from version 4.2.8p6 to version 4.2.8p10.
I watched the daemon log and I can see a lot of entries like this:
Mar 28 09:11:01 gps0 ntpd[2445]: 0.0.0.0 0168 08 no_sys_peer
Mar 28 09:11:03 gps0 ntpd[2445]: PPS(0) 916a 8a sys_peer
Mar 28 09:11:17 gps0 ntpd[2445]: 0.0.0.0 0178 08 no_sys_peer
Mar 28 09:12:21 gps0 ntpd[2445]: PPS(0) 917a 8a sys_peer
Mar 28 09:13:57 gps0 ntpd[2445]: 0.0.0.0 0188 08 no_sys_peer
Mar 28 09:14:13 gps0 ntpd[2445]: PPS(0) 918a 8a sys_peer
Mar 28 09:15:17 gps0 ntpd[2445]: 0.0.0.0 0198 08 no_sys_peer
Mar 28 09:17:09 gps0 ntpd[2445]: PPS(0) 919a 8a sys_peer
Mar 28 09:21:25 gps0 ntpd[2445]: 0.0.0.0 01a8 08 no_sys_peer
Mar 28 09:21:57 gps0 ntpd[2445]: PPS(0) 91aa 8a sys_peer
Mar 28 09:22:13 gps0 ntpd[2445]: 0.0.0.0 01b8 08 no_sys_peer
Looking with ntpq after a no_sys_peer I see:
# ntpq -pn
remote refid st t when poll reach delay offset jitter
==============================================================================
x127.127.22.0 .PPS. 0 l 7 16 377 0.000 -0.068 0.119
x127.127.28.0 .GPS. 0 l 7 16 377 0.000 -4.665 0.688
So in more or less regular intervals ntpd goes into state "falsetick" but comes back to status "pps" and so on.
I changed back to version 4.2.8p6 and everything is fine.
I have a small script where I can see availability. In file "plot_486p10.png" you can see that the bottom line between 07:00 and 08:00 jumps between "falsetick" and "pps".
This is the time frame where I run version 4.2.8p10.
A day before "plot_486p6.png" shows ( where I run version 4.2.8p6 ) the driver 127.127.22.0 is constantly available.
In a test environment I figured out the issue exists with version 4.2.8p9 too. So something changed in the last 4 patch level versions.
To locate the issue a little bit I removed driver 127.127.28.0 and I used another ntp server over IP as a "preferred server".
In this case version 4.2.8p10 works fine with 127.127.22.0. So it must have something to do with the shared memory driver 127.127.28.0
Any ideas what I could do to fix this issue ?
Did someone else figure out the same issue ?
Is it worth to open a ticket ?
Kind regards
Hans
--
Ing. Dipl.-Ing. Hans Mayer
Systems Administrator
Information and Communication Technologies (ICT)
International Institute for Applied Systems Analysis (IIASA)
Schlossplatz 1
A-2361 Laxenburg, Austria
Phone: +43 2236 807 Ext 215
Mobile: +43 676 83 807 215
Web: http://www.iiasa.ac.at
E-Mail: mayer at iiasa.ac.at
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