[etherlab-users] Xenomai performance

[Graeme Foot]

Hi,

I don't use xenomai so can't comment on that side, but just curious, how many ethercat modules do you have? 

Also, if you run the ethercat command:
ethercat slaves -v | grep 'transmission delay'

What is the delay time at the last module?

This is how long the ethercat frame takes to reach that module.  It will then also take the same amount of time to return (assuming a linear topology).  You will also need to factor in processing time overhead of the master to prepare and send the frame and receive the frame, and also add the worst case jitter time.  This is in theory the shortest turnaround time you can expect per frame.  It does not factor in any processing time your application may need.

Regards,
Graeme.


-----Original Message-----
From: etherlab-users [mailto:etherlab-users-bounces at etherlab.org] On Behalf Of Christoph Schröder
Sent: Thursday, 29 September 2016 3:25 a.m.
To: etherlab-users at etherlab.org
Subject: [etherlab-users] Xenomai performance

Hi all,

I am currently testing the EtherCAT master with Xenomai 2.6.5 on a Debian wheezy (ipipe patched kernel 3.2). Using the xenomai example from the master I can go up to 12,5kHz (maybe a bit more). I got lost frames from time to time if I go up to 15kHz and a lot of lost frames if I go up to 20kHz.
This is a lot better than non-rt, but in the master documentation there was noted that they could go up to 25kHz on a 2GHz System with RTAI. My testsystem is a Core i5-4690 CPU @ 3.50GHz. I configured everything as described in the Xenomai installation instruction. Are my results reasonable resp. is RTAI simply better or should I expect some misconfiguration?

My results from the xenomai latency test seem to be fine.
$ sudo ./xeno latency -T 25
== Sampling period: 100 us
== Test mode: periodic user-mode task
== All results in microseconds
warming up...
RTT|  00:00:01  (periodic user-mode task, 100 us period, priority 99)
RTH|----lat min|----lat avg|----lat max|-overrun|---msw|---lat
best|--lat worst
RTD|     -2.307|     -2.152|      0.550|       0|     0| -2.307|      0.550
RTD|     -2.516|     -2.160|      4.011|       0|     0| -2.516|      4.011
RTD|     -2.319|     -2.170|      0.515|       0|     0| -2.516|      4.011
RTD|     -2.324|     -2.165|     -0.322|       0|     0| -2.516|      4.011
RTD|     -2.336|     -2.127|      2.644|       0|     0| -2.516|      4.011
RTD|     -2.350|     -2.146|      2.139|       0|     0| -2.516|      4.011
RTD|     -2.542|     -2.160|     -0.075|       0|     0| -2.542|      4.011
RTD|     -2.363|     -2.146|      2.111|       0|     0| -2.542|      4.011
RTD|     -2.590|     -2.156|      0.461|       0|     0| -2.590|      4.011
RTD|     -2.703|     -2.158|     -1.017|       0|     0| -2.703|      4.011
RTD|     -2.701|     -2.157|      6.590|       0|     0| -2.703|      6.590
RTD|     -2.695|     -2.156|     -1.049|       0|     0| -2.703|      6.590
RTD|     -2.684|     -2.158|      0.496|       0|     0| -2.703|      6.590
RTD|     -2.712|     -2.154|     -1.079|       0|     0| -2.712|      6.590
RTD|     -2.693|     -2.158|      6.106|       0|     0| -2.712|      6.590
RTD|     -2.700|     -2.159|     -1.005|       0|     0| -2.712|      6.590
RTD|     -2.712|     -2.156|     -0.882|       0|     0| -2.712|      6.590
RTD|     -2.642|     -2.159|     -0.836|       0|     0| -2.712|      6.590
RTD|     -2.608|     -2.152|      5.227|       0|     0| -2.712|      6.590
RTD|     -2.686|     -2.158|     -0.742|       0|     0| -2.712|      6.590
RTD|     -2.653|     -2.158|      0.883|       0|     0| -2.712|      6.590
RTT|  00:00:22  (periodic user-mode task, 100 us period, priority 99)
RTH|----lat min|----lat avg|----lat max|-overrun|---msw|---lat
best|--lat worst
RTD|     -2.723|     -2.160|     -1.258|       0|     0| -2.723|      6.590
RTD|     -2.643|     -2.161|      0.059|       0|     0| -2.723|      6.590
RTD|     -2.366|     -2.168|     -0.458|       0|     0| -2.723|      6.590
---|-----------|-----------|-----------|--------|------|----------------
---|-----------|-----------|-----------|--------|------|---------
RTS|     -2.723|     -2.156|      6.590|       0|     0| 00:00:25/00:00:25

Thanks and best regards,
Christoph

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