[etherlab-users] yet another datagrams UNMATCHED - DC 0.2ms / 5kHz // igb kernel 3.18

Christoph Schroeder christoph.schroeder at helmholtz-berlin.de
Tue Feb 13 14:12:24 CET 2018

Hi Jürgen,

On 02/13/2018 10:01 AM, Jürgen Walter • DATATRONiQ wrote:
I see- will get another Intel card (although compatible ones (kernel driver e1000, e1000e) seem to be hard to come by these days) and try with anther kernel driver.
I also did some tests with the EtherCAT master, Xenomai and different network devices compatible with the ec_e1000e driver.
Test system was a Core-i5 (4th generation) with a Debian Wheezy  (Kernel 3.2) with two slaves attached (Microship LAN9252 in simple Digital I/O mode). I observed the following:

  *   even with the PREEMPT patch and the native driver ec_e1000e I could barely achieve 2000Hz cycle rate without frame losses
  *   with Xenomai I could go over 10000Hz without a problem, but there are some other issues with Xenomai:
     *   the EtherCAT master is not ready to use the newer Xenomai 3.x branch and the Xenomai 2.x branch is not supported anymore
     *   I got some issues with long term stability on my test system (Kernel panic) and decided not to use it on a productive system
     *   I would suggest you go for RTAI since you will also get far more help from the EtherCAT community, I could barely find other people here who also use Xenomai with the EtherCAT master
  *   while using Xenomai I observed, that there is also a huge difference between different network chips:
     *   I initially used a card with an Intel 82572EI (introduced Q4'05) and also tried a Dual port card with an Intel 82571EB (introduced Q3'05) which had basically the same results on my test system
     *   the best results I got were achieved with an Intel 82574L (introduced Q2'0)

I didn't try RTAI till now, but I think you will get the same or even better results than I got with Xenomai.

The cards with Intel 82574L we got were sold as "Intel Gigabit CT Desktop Adapter". The chip will be produced until 2020, so getting a card with it should be no problem. Maybe this will help you.

Best regards,


Helmholtz-Zentrum Berlin für Materialien und Energie GmbH

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