Re: Chrony on CM4

On Mon, Sep 4, 2023 at 6:51 PM Miroslav Lichvar <[email protected]> wrote:

> On Mon, Sep 04, 2023 at 06:30:06PM +0700, James Clark wrote:
> > "chronyc serverstats" looks good: I'm seeing  increasing "NTP hardware RX
> > timestamps" and
> > "NTP hardware TX timestamps".
>
> Is the server running on CM4?
>

Yes.


> > I'm now trying two clients, and I see different results with chronyc
> > ntpdata:
> >
> > - another CM4: here I see RX timestamping : Hardware but TX timestamping
> :
> > Kernel
>
> Can you please enable the measurements log and see if all TX
> timestamps are kernel or there is a mix of kernel and hardware?


It's a mixture: 848 "K H"; 22 "K K"; 13 "H H".


> The HW
> timestamping might be unreliable. You could try increasing hwtstimeout
> to 1 to wait even longer for the TX timestamp.
>
> You could also try adding "minpoll 2" to the hwtimestamp directive to
> read the clock less frequently to avoid some collisions with the
> timestamping access. IIRC the HW or driver might have an issue with
> that.
>

 I tried increasing both hwtstimeout and minpoll, but it hasn't fixed the
problem.

> - an x86 box with the AQC107: here I see TX timestamping : Hardware and RX
> > timestamping : Hardware
> > but on the client "chronyc ntpdata" shows Kernel for TX timestamping and
> RX
> > timestamping.
>
> I have no experience with this NIC. What does ethtool -T show?
>

It shows:

Time stamping parameters for enp1s0:
Capabilities:
        hardware-transmit
        software-transmit
        hardware-receive
        software-receive
        software-system-clock
        hardware-raw-clock
PTP Hardware Clock: 3
Hardware Transmit Timestamp Modes:
        off
        on
Hardware Receive Filter Modes:
        none
        ptpv2-l4-event
        ptpv2-l2-event
        ptpv2-event

The measurements here are consistently K K, apart from the first one which
is H H.

James