linuxptp-users

[Linuxptp-users] Use NIC as PTP GM without external sync

[Nils F. <nil...@sr...>]

Hello everyone!

I am trying to use a NIC as a PTP GM with any external sync sorce. I 
have a PC with a dual port NIC (82599ES 10-Gigabit SFI/SFP+) connected 
to an embedded device over Ethernet. I use a SFP-to-Ethernet adapter to 
translate from SFP+ to Ethernet. Both devices need to be synced but I 
cannot use GPS or other external clock sources. My idea is to use the 
NIC as a PTP GM and serve the embedded device with PTP. What I am not 
sure about is if I need to use phc2sys to sync NIC and the physical 
clock of the machine hosting the NIC? What quality of sync can I expect?

With my current configuration I have some PTP coming in but the quality 
is really bad. On the embedded device I see the following:

ptp4l[2023/10/19/12:28:03]: state=2 rms 901387699 max 1000000058 freq  
+1353 +/-  78 delay 20569 +/-  16
ptp4l[2023/10/19/12:28:04]: state=2 rms 1245 max 4879 freq  +1213 +/-   
4 delay 20539 +/-  32
ptp4l[2023/10/19/12:28:05]: state=2 rms  132 max  242 freq  +1196 +/-   
7 delay 20442 +/-  35
ptp4l[2023/10/19/12:28:06]: state=2 rms 1031 max 4050 freq  +1158 +/-  
53 delay 20427 +/-  20
ptp4l[2023/10/19/12:28:07]: state=2 rms  172 max  381 freq  +1065 +/-   
0 delay 20401 +/-  11
ptp4l[2023/10/19/12:28:08]: state=2 rms   69 max  153 freq  +1020 +/-  
13 delay 20400 +/-  16
ptp4l[2023/10/19/12:28:09]: state=2 rms  105 max  300 freq  +1021 +/-   
4 delay 20392 +/-  10
ptp4l[2023/10/19/12:28:10]: state=2 rms  222 max  518 freq  +1020 +/-   
0 delay 20436 +/-  13
ptp4l[2023/10/19/12:28:11]: state=2 rms 968245340 max 999999669 freq   
+992 +/-   0 delay 20507 +/-  36
ptp4l[2023/10/19/12:28:13]: state=2 rms 433012546 max 999999740 freq   
+921 +/-  28 delay 20559 +/-  31
ptp4l[2023/10/19/12:28:14]: state=2 rms  139 max  279 freq   +919 +/-   
2 delay 20586 +/-  34
ptp4l[2023/10/19/12:28:15]: state=2 rms  153 max  263 freq   +922 +/-   
4 delay 20671 +/-  22
ptp4l[2023/10/19/12:28:16]: state=2 rms 433012402 max 999999485 freq   
+976 +/-  87 delay 20681 +/-   3
ptp4l[2023/10/19/12:28:18]: state=2 rms 968245358 max 999999677 freq  
+1084 +/- 110 delay 20724 +/-  18
ptp4l[2023/10/19/12:28:19]: state=2 rms  313 max  566 freq   +803 +/-   
3 delay 20727 +/-  16

Is this because I don't have an external clock source or is it about how 
I have configured the PTP GM? I have uploaded both configs to pastebin, 
you'll find the pastes here:

PTP GM: https://pastebin.com/9cRBEZZn

PTP Clien emb. device: https://pastebin.com/RtECRXCe

I cannot adjust the config on the embedded device but I can adjust the 
config on the PTP GM. But unfortunately, I am not sure what I am doing 
wrong. I would really appreciate any help! Thanks in advance!

Best regards

Nils

Re: [Linuxptp-users] Use NIC as PTP GM without external sync

[Miroslav L. <mli...@re...>]

On Thu, Oct 19, 2023 at 02:40:30PM +0200, Nils Fuerste wrote:
> Hello everyone!
> 
> I am trying to use a NIC as a PTP GM with any external sync sorce. I have a
> PC with a dual port NIC (82599ES 10-Gigabit SFI/SFP+) connected to an
> embedded device over Ethernet. I use a SFP-to-Ethernet adapter to translate
> from SFP+ to Ethernet. Both devices need to be synced but I cannot use GPS
> or other external clock sources. My idea is to use the NIC as a PTP GM and
> serve the embedded device with PTP. What I am not sure about is if I need to
> use phc2sys to sync NIC and the physical clock of the machine hosting the
> NIC? What quality of sync can I expect?

You can leave the clock of the NIC running free if you don't need the
client's clock to be accurate, only synchronized to the server.

> ptp4l[2023/10/19/12:28:10]: state=2 rms  222 max  518 freq  +1020 +/-   0
> delay 20436 +/-  13
> ptp4l[2023/10/19/12:28:11]: state=2 rms 968245340 max 999999669 freq   +992
> +/-   0 delay 20507 +/-  36
> ptp4l[2023/10/19/12:28:13]: state=2 rms 433012546 max 999999740 freq   +921
> +/-  28 delay 20559 +/-  31

Those errors are almost exactly 1 second, which is very suspicious. It
could be a driver bug. What kernel version do you use? It would help
if you could get a third device and see if it works better as a server
or client to determine on which side is the problem.

-- 
Miroslav Lichvar

Re: [Linuxptp-users] Use NIC as PTP GM without external sync

[Nils F. <nil...@sr...>]

On 19/10/23 14:51, Miroslav Lichvar wrote:
> On Thu, Oct 19, 2023 at 02:40:30PM +0200, Nils Fuerste wrote:
> ptp4l[2023/10/19/12:28:10]: state=2 rms  222 max  518 freq  +1020 +/-   0
> delay 20436 +/-  13
> ptp4l[2023/10/19/12:28:11]: state=2 rms 968245340 max 999999669 freq   +992
> +/-   0 delay 20507 +/-  36
> ptp4l[2023/10/19/12:28:13]: state=2 rms 433012546 max 999999740 freq   +921
> +/-  28 delay 20559 +/-  31
> Those errors are almost exactly 1 second, which is very suspicious. It
> could be a driver bug. What kernel version do you use? It would help
> if you could get a third device and see if it works better as a server
> or client to determine on which side is the problem.
>
As proposed I have tested some other scenarios. During this process I 
have realized that the PTP version on the embedded device is probably 
not mainline. I have copied the config to another machine with mainline 
PTP and it was complaining about many parameters in the PTP client 
config of the embedded device.

I have used some other configuration to narrow down the issue. These are 
the results:

- Using other master, same client, same configs -> Same result

- Using other master, other client with  config from embedded device -> 
Results are worse than before (I had to comment out some config items 
that were not recognized by ptp4l.

- Using a proper PTP GM (Qulsar Q2), original client (embedded device) 
-> Good sync, around rms 20 +- 5

- I have tested different SFP to Ethernet adapters in all of those tests 
above, sync quality stayed the same


What can I do? Since a proper PTP GM can provide a good PTP sync to the 
client I guess my config is faulty? Or can it be something else? Can I 
maybe do some more tests?

Many thanks!
Nils