Re: [Linuxptp-users] High path delay: i219 vs i210?

[Joseph M. <jos...@gm...>]

Hi,

I don't have an answer to your question, but I can share from my experience
that I'm familiar with this. I even posted a similar question a year or so
ago.
I also tried to open a ticket in Intel Customer Service but nothing good
came through.
Maybe the e1000e developers community would have an idea (but I didn't try
to ask there).

My problem with the i219 NIC was that with no traffic the path delay was
around ~7 or 8 usec (as you mentioned), but in intervals of high load of
traffic the path delay decreased significantly to something like 800 nsec
(0.8 usec).
These significant changes in the path delay between 8 usec to 0.8 usec
caused me lots of accurecy troubles... (and I didn't use any switch between
my master and slave).
However, from the tests I was doing, the i210 doesn't suffer from this
behaviour.
Intel Customer Service didn't know to answer if this is a bug or perhaps a
feature that can be switched off/on.

Hope it helped somehow...
Joseph

On Fri, Mar 18, 2022 at 12:44 PM <ps...@we...> wrote:

> Hello,
>
> I have a problem with the high of the calculated path delay. I am using
> hardware timestamping and thought I get values less than 20ns. But i have
> values over 7.8µs is that normal?
> I have also tested the usecase with an i210, there I got 250ns, but these
> are also quite high.
>
> Questions:
> 1. why are the values of i219 and i210 so different? what does the path
> delay depend on?
> 2. if it depends only on the NIC, where can I find out which NIC is the
> best one for hardware time stamping, which keywords in the datasheet are
> important?
> 3. Is there a driver problem or is it possible to change something at the
> ptp-files to get better values?
>
> NIC: I2019-V rev 21
> driver: e1000e - 3.8.4-NAPI
> Kernel:5.4.0-104-generic
>
> output of: ethtool -T enp0s31f6:
> Time stamping parameters for enp0s31f6:
> Capabilities:
>         hardware-transmit     (SOF_TIMESTAMPING_TX_HARDWARE)
>         software-transmit     (SOF_TIMESTAMPING_TX_SOFTWARE)
>         hardware-receive      (SOF_TIMESTAMPING_RX_HARDWARE)
>         software-receive      (SOF_TIMESTAMPING_RX_SOFTWARE)
>         software-system-clock (SOF_TIMESTAMPING_SOFTWARE)
>         hardware-raw-clock    (SOF_TIMESTAMPING_RAW_HARDWARE)
> PTP Hardware Clock: 0
> Hardware Transmit Timestamp Modes:
>         off                   (HWTSTAMP_TX_OFF)
>         on                    (HWTSTAMP_TX_ON)
> Hardware Receive Filter Modes:
>         none                  (HWTSTAMP_FILTER_NONE)
>         all                   (HWTSTAMP_FILTER_ALL)
>         ptpv1-l4-sync         (HWTSTAMP_FILTER_PTP_V1_L4_SYNC)
>         ptpv1-l4-delay-req    (HWTSTAMP_FILTER_PTP_V1_L4_DELAY_REQ)
>         ptpv2-l4-sync         (HWTSTAMP_FILTER_PTP_V2_L4_SYNC)
>         ptpv2-l4-delay-req    (HWTSTAMP_FILTER_PTP_V2_L4_DELAY_REQ)
>         ptpv2-l2-sync         (HWTSTAMP_FILTER_PTP_V2_L2_SYNC)
>         ptpv2-l2-delay-req    (HWTSTAMP_FILTER_PTP_V2_L2_DELAY_REQ)
>         ptpv2-event           (HWTSTAMP_FILTER_PTP_V2_EVENT)
>         ptpv2-sync            (HWTSTAMP_FILTER_PTP_V2_SYNC)
>         ptpv2-delay-req       (HWTSTAMP_FILTER_PTP_V2_DELAY_REQ)
>
> I use a i219-Notebook with following command as a slave: sudo ptp4l -P -H
> -l 7 -i enp0s31f6 -m -s
> The "Master"-command is simmiliar just with another interface and without
> -s.
> Output:
> ptp4l[183917.707]: selected best master clock 70ff76.fffe.1dea84
> ptp4l[183917.707]: port 1 (enp0s31f6): LISTENING to UNCALIBRATED on
> RS_SLAVE
> ptp4l[183918.444]: port 1 (enp0s31f6): delay timeout
> ptp4l[183918.445]: delay   filtered       7358   raw       7319
> ptp4l[183918.707]: master offset     239333 s0 freq  +45884 path delay
>  7858
> ptp4l[183919.444]: port 1 (enp0s31f6): delay timeout
> ptp4l[183919.445]: delay   filtered       7358   raw       7422
> ptp4l[183919.707]: master offset     239368 s1 freq  +45919 path delay
>  7858
> ptp4l[183920.444]: port 1 (enp0s31f6): delay timeout
> ptp4l[183920.445]: delay   filtered       7349   raw       7345
> ptp4l[183920.708]: master offset       -464 s2 freq  +45455 path delay
>  7849
> ptp4l[183920.708]: port 1 (enp0s31f6): UNCALIBRATED to SLAVE on
> MASTER_CLOCK_SELECTED
> ptp4l[183921.445]: port 1 (enp0s31f6): delay timeout
> ptp4l[183921.445]: delay   filtered       7349   raw       7336
> ptp4l[183921.709]: master offset       -485 s2 freq  +45295 path delay
>  7849
> ptp4l[183922.445]: port 1 (enp0s31f6): delay timeout
> ptp4l[183922.446]: delay   filtered       7349   raw       7365
> ptp4l[183922.709]: master offset         27 s2 freq  +45661 path delay
>  7849
> ptp4l[183923.445]: port 1 (enp0s31f6): delay timeout
> ptp4l[183923.446]: delay   filtered       7340   raw       7330
> ptp4l[183923.709]: master offset        137 s2 freq  +45779 path delay
>  7840
>
>
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