Hi,
We are currently using LinuxPTP on an embedded linux platform (ARMv8) and are
experiencing some problems with dropped sync seemingly due to packet reordering.
I have traced the sync and follow up messages and I see that sometimes a follow
up message and the next sync message are reordered, resulting in the processing
of two sync messages before the follow up is processed. When this occurs the
sync timer expires sometimes (not always), as seen in the below trace.
ptp4l[66088.453]: delay filtered 859 raw 868
ptp4l[66088.563]: process_sync: seqnum=63375 ts=332240.686307221
ptp4l[66088.563]: process_follow_up: seqnum=63375 ts=332240.686306278
ptp4l[66088.688]: process_sync: seqnum=63376 ts=332240.811907459
ptp4l[66088.688]: process_follow_up: seqnum=63376 ts=332240.811906550
ptp4l[66088.813]: process_sync: seqnum=63377 ts=332240.936953726
ptp4l[66088.814]: process_follow_up: seqnum=63377 ts=332240.936952818
ptp4l[66088.938]: process_sync: seqnum=63378 ts=332241.061994001
ptp4l[66088.939]: process_follow_up: seqnum=63378 ts=332241.061993078
ptp4l[66088.939]: rms 59 max 84 freq +565 +/- 42 delay 859 +/- 0
ptp4l[66089.063]: process_sync: seqnum=63379 ts=332241.187008817
ptp4l[66089.189]: process_sync: seqnum=63380 ts=332241.312630776
ptp4l[66089.189]: process_follow_up: seqnum=63379 ts=332241.187007894
ptp4l[66089.189]: process_follow_up: seqnum=63380 ts=332241.312629830
ptp4l[66089.314]: process_sync: seqnum=63381 ts=332241.437660268
ptp4l[66089.439]: port 1: rx sync timeout
Looking at the code (process_sync, process_follow_up and port_syfusfm) it seems
that the intention is to handle the case when a follow up is processed before
the corresponding sync, not when the next sync is received before the follow
up. Is this a known issue and has anyone made any fix for this?
Best regards,
Mikael Arvids
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