Re: [Linuxptp-users] Question regarding ptp4l

[Nemo C. <nem...@gm...>]

 Hi Richard,

Did you get chance to see this? I am still looking for help on this.

Thanks

    On Friday, 7 October, 2022 at 11:04:33 am GMT-4, vignesh shanmugam via Linuxptp-users <lin...@li...> wrote:  
 
  Hi Richard,
This is Intel CPU, has support for HW timestamping in the MAC.

I also found few more issues when analyzing the logs and pcap,

In two hours of test, I see 8 times tx_timestamp timeout issue for path delay. 

ptp4l[5818.284]: timed out while polling for tx timestamp
ptp4l[5818.284]: increasing tx_timestamp_timeout may correct this issue, but it is likely caused by a driver bug
ptp4l[5818.284]: port 1: send peer delay request failed
ptp4l[5818.284]: port 1: SLAVE to FAULTY on FAULT_DETECTED (FT_UNSPECIFIED)


And when this happens, ptp4l stops synchronizing the local time for almost 14 to 15 sec. Only phc2sys is active. I am not sure if this is related to the jump I see. 
1. Can you please explain if this is expected?
2. Why would ptp4l stop if pdelay request send fails? 
3. Why can't ptp4l keep receiving the SYNC/FollowUp and use the last known path delay for synchronizing the local clock?

The other issue I found was, the "cumulativeScaledRateOffset" received in the FollowUp TLV has a spike continuously for a while, this is exactly when the slave jumped to 32 us offset. I have shown the snippet below.




4. Could you please tell me why this spike would happen continously?
5. I also see such spikes elsewhere, but not as 5 consecutive times as shown in the above. Would this contribute to the jump?

Thanks!



    On Friday, 7 October, 2022 at 10:08:03 am GMT-4, Richard Cochran <ric...@gm...> wrote:  
 
 On Thu, Oct 06, 2022 at 06:44:29PM +0000, vignesh shanmugam via Linuxptp-users wrote:
> Can you point me some clues what could cause this?

What is the MAC?  Does it use software time stamping?

Thanks,
Richard
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