On Thu, Feb 28, 2019 at 12:35 AM Harini Katakam <hari...@xilinx.com> wrote:
>
> Hi Paul,
>
> > -----Original Message-----
> > From: Paul Thomas [mailto:pthomas8...@gmail.com]
> > Sent: Thursday, February 28, 2019 3:36 AM
> > To: linuxptp-devel@lists.sourceforge.net
> > Subject: strangeness
> >
> <snip>
> > HW/SW setup:
> > This is on an arm64 system (xilinx zynqmp) using the macb ethernet driver:
> > https://xilinx-wiki.atlassian.net/wiki/spaces/A/pages/18841740/Macb+Driver
>
> Some issues were reported when ptp4l was used in conjunction with SSH and
> while they were not easily reproduced, the errors stopped completely after 
> this
> patch in the Xilinx tree:
> https://github.com/Xilinx/linux-xlnx/commit/835b6170df72dc73d9386b5838e7f16c09953b9a#diff-41909d180431659ccc1229aa30fd4e5a
>
> It timestamps only PTP event packets as opposed to all packets (which is 
> excessive).
> There are also some BD word related stability fixes but I see that you've 
> already
> used mainline 5.0 kernel - so they should already be in there.
>
> Regards,
> Harini

Hi Harini,

This is very reproducible now, and with further nc testing it almost
seems like the tx packets aren't getting sent until there is rx
traffic. Let me describe the setup, on my host I run the nc server and
then on the zynqmp board I run the nc client. In the "After" case in
the example below you can see that the c4 line doesn't come to the
server until s7 is sent. In this test sN lines are typed from the
server and cN lines are typed from the client where N is the overall
order. In the "Before" case the overall order is correct.
Before running ptp4l:
zynqmp client side     host nc server
$ nc host 4567           $ nc -l 4567
s1                             s1
s2                             s2
c3                             c3
c4                             c4
s5                             s5
s6                             s6
s7                             s7

After running ptp4l:
zynqmp client side     host nc server
$ nc host 4567           $ nc -l 4567
s1                             s1
s2                             s2
c3                             s5
c4                             s6
s5                             c3
s6                             s7
s7                             c4

At first I was thinking it was possibly the tx interrupt, but that
maybe doesn't make sense because in a separate (already established)
ssh session I can generate lot's of traffic in both directions and it
never causes the c3/c4 lines to show up on the server nc. It is not
until the traffic on that actual port.

thanks,
Paul


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