Closed sasharozenson closed 2 months ago
Update: After further investigation, I discovered the assume_one_phc_per_nic off
option. This setting seems relevant for our case, as it prevents the assumption that only one PHC exists per NIC.
I will test with this option and report back with results. Thanks.
Hi @sasharozenson,
Thanks for raising and closing this issue!
The assume_one_phc_per_nic
feature was added to help with some third party NICs that provided multiple phc
instances but which represented the same underlying clock. That is a scenario that doesn't work very well with sfptpd
because sfptpd
by default auto-discovers all the NIC clocks to sink them together - a feature of the monolithic design of sfptpd
in contrast with some other software.
However, this workaround turns out not to be an effective solution and also doesn't work well in the case you have found where the clocks really are independent as advertised.
The next release of sfptpd
disables this feature by default (ChangeLog entry).
The current recommendation for users of third party NICs where multiple phc
devices are present that are not independent is to list the clocks to be synced explicitly with the clock_list
option. This is not relevant for you, however.
Andrew
Summary
When using
sfptpd
(version 3.7.1.1007) with Mellanox Technologies MT27710 Family [ConnectX-4 Lx], the daemon incorrectly picks the phc clock. This results in incorrect timestamps being applied.Steps to Reproduce
Manually set the PTP time on active interface, on which PTP Feed is being sent -
/dev/ptp5
(name:enp5s0f1np1
):Expected time:
Sun Sep 9 04:16:55 2001
Start
systemctl start sfptpd
.The daemon incorrectly selects
phc4
(associated with inactive interfaceenp5s0f0np0
):When fetching the time for
/dev/ptp4
, it shows the incorrect date, fast-forwarding by 23 years:Meanwhile,
/dev/ptp5
still retains the manually set timestamp:Expected Behavior
The daemon should pick the correct PTP clock (
phc5
, notphc4
), corresponding to the interfaceenp5s0f1np1
, and properly sync the time without any large jumps.Actual Behavior
The clock is unexpectedly advanced by 23 years due to the wrong PTP clock (
phc4
) being selected. This happens even withtimestamping_interfaces
andinterface
explicitly set toenp5s0f1np1
.Debug Information
Output showing two interfaces, each with its own PTP clock:
Hardware: Mellanox Technologies MT27710 Family [ConnectX-4 Lx]
SFPTPD: 3.7.1.1007
OS: Debian 11 "Bullseye"