Hi all,
I seem to run into increasing offsets constantly when running ptp4l or
phc2sys in various combinations and with various options.
New to PTP, I am trying to implement it on a Fedora Core 25 image (I know,
rather old...) on a I210 network chip which supports hardware time stamping.
Initially, I installed with dnf install linuxptp which was version 1.7.
Later I downloaded and installed latest version from sourceforge (3.1.1).
Since I have no grandmaster clock nor a PTP compliant switch, I connected 2
computers directly.
While no grandmaster clock, I thought to use the system clock as master and
slave the PHC to the system clock by using phc2sys on 1 computer
(experiment 1)
Next step would be to synchronize a second computer to the first computer
(experiment 2)
Experiment 1:
phc2sys -s CLOCK_REALTIME -c eth0 -O 0 -m
gives the following output:
phc2sys[1040.475]: sys offset -76090251872 s0 freq -23999998 delay 736
phc2sys[1041.475]: sys offset -76834355556 s1 freq -23999999 delay 736
phc2sys[1042.476]: sys offset -744083717 s2 freq -23999999 delay 736
phc2sys[1043.476]: clockcheck: clock jumped backward or running slower
than expected!
phc2sys[1043.476]: sys offset -1488162238 s0 freq -23999999 delay 736
phc2sys[1044.476]: clockcheck: clock jumped backward or running slower
than expected!
phc2sys[1044.476]: sys offset -2232260194 s0 freq -23999999 delay 736
phc2sys[1045.476]: clockcheck: clock jumped backward or running slower
than expected!
phc2sys[1045.476]: sys offset -2976349047 s0 freq -23999999 delay 736
phc2sys[1046.476]: clockcheck: clock jumped backward or running slower
than expected!
phc2sys[1046.476]: sys offset -3720439785 s0 freq -23999999 delay 736
...
phc2sys[1059.478]: clockcheck: clock jumped backward or running slower
than expected!
phc2sys[1059.478]: sys offset -13393624210 s0 freq -23999999 delay 704
phc2sys[1060.478]: clockcheck: clock jumped backward or running slower
than expected!
phc2sys[1060.478]: sys offset -14137705401 s0 freq -23999999 delay 736
...
phc2sys[1075.480]: clockcheck: clock jumped backward or running slower
than expected!
phc2sys[1075.480]: sys offset -25299057751 s0 freq -23999999 delay 736
phc2sys[1076.480]: clockcheck: clock jumped backward or running slower
than expected!
phc2sys[1076.480]: sys offset -26043146441 s0 freq -23999999 delay 736
Experiment 2:
master: ptp4l -i eth0 -m
slave: ptp4l -i eth0 -m -s
Master gives output:
ptp4l[1285.052]: selected /dev/ptp0 as PTP clock
ptp4l[1285.052]: port 1: INITIALIZING to LISTENING on INITIALIZE
ptp4l[1285.052]: port 0: INITIALIZING to LISTENING on INITIALIZE
ptp4l[1291.462]: port 1: LISTENING to MASTER on
ANNOUNCE_RECEIPT_TIMEOUT_EXPIRES
ptp4l[1291.462]: selected best master clock 001395.fffe.3329f2
ptp4l[1291.462]: assuming the grand master role
Slave gives output:
ptp4l[1307.595]: selected /dev/ptp0 as PTP clock
ptp4l[1307.595]: port 1: INITIALIZING to LISTENING on INITIALIZE
ptp4l[1307.596]: port 0: INITIALIZING to LISTENING on INITIALIZE
ptp4l[1307.919]: port 1: new foreign master 001395.fffe.3329f2-1
ptp4l[1311.919]: selected best master clock 001395.fffe.3329f2
ptp4l[1311.919]: port 1: LISTENING to UNCALIBRATED on RS_SLAVE
ptp4l[1312.918]: master offset 1895520235628 s0 freq -18003277 path delay
0
ptp4l[1313.918]: master offset 1895520228878 s1 freq -18030763 path delay
5343
ptp4l[1315.918]: clockcheck: clock jumped backward or running slower than
expected!
ptp4l[1315.918]: master offset 9696846 s0 freq -18030763 path delay
-680343
ptp4l[1316.918]: clockcheck: clock jumped backward or running slower than
expected!
ptp4l[1316.918]: master offset 14682690 s0 freq -18030763 path delay
-1159889
ptp4l[1317.918]: clockcheck: clock jumped backward or running slower than
expected!
ptp4l[1317.920]: master offset 19362056 s0 freq -18030763 path delay
-1333023
ptp4l[1318.918]: clockcheck: clock jumped backward or running slower than
expected!
ptp4l[1318.918]: master offset 23868345 s0 freq -18030763 path delay
-1333023
ptp4l[1319.918]: clockcheck: clock jumped backward or running slower than
expected!
ptp4l[1319.918]: master offset 28201513 s0 freq -18030763 path delay
-1159889
ptp4l[1320.918]: clockcheck: clock jumped backward or running slower than
expected!
ptp4l[1320.918]: master offset 32534672 s0 freq -18030763 path delay
-986755
ptp4l[1321.918]: clockcheck: clock jumped backward or running slower than
expected!
ptp4l[1321.918]: master offset 37214040 s0 freq -18030763 path delay
-1159889
...
ptp4l[1330.918]: clockcheck: clock jumped backward or running slower than
expected!
ptp4l[1330.918]: master offset 77796465 s0 freq -18030763 path delay
-1185816
ptp4l[1331.918]: clockcheck: clock jumped backward or running slower than
expected!
ptp4l[1331.918]: master offset 82472537 s0 freq -18030763 path delay
-1355555
...
ptp4l[1341.918]: clockcheck: clock jumped backward or running slower than
expected!
ptp4l[1341.918]: master offset 127082899 s0 freq -18030763 path delay
-903187
ptp4l[1342.918]: clockcheck: clock jumped backward or running slower than
expected!
ptp4l[1342.918]: master offset 131589224 s0 freq -18030763 path delay
-903187
ptp4l[1343.918]: clockcheck: clock jumped backward or running slower than
expected!
ptp4l[1343.918]: master offset 136095456 s0 freq -18030763 path delay
-903187
(The above outputs are from version 1.7. The 3.1.1 version gives similar
results)
Whatever I try , there is never a converging offset value. Also the freq
seems to be constant and the opposite direction of the offset. It seems to
me that the correction of the servo has no effect.
Any clue or hints are welcome. Thanks!
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