Dear Martin
I followed your suggestions
Now we installed kernel 3.2.57-rt83 ( patch rt83 )
Application runs at 1.5 Millisecond
Now Priority of Ethercat-OP is 99 and application is 80
with FIFO Scheduler
Working counter sometimes is still from 139/139 to 0/139
And with ethercat debug 1 .... show a couple of dumped frames
it may happen every 20 minutes but it's occasional...
may not happen for an hour or 2
I saw in your email you use 3.10.x series...
Would it have best performance in this case ?
This command :
*$ NETDEVNAME=eth1*
*>$ ethtool --coalesce $NETDEVNAME adaptive-rx off adaptive-tx off
rx-usecs 0 rx-frames 0 rx-usecs-irq 0 rx-frames-irq 0 tx-usecs 0
tx-frames 0 tx-usecs-irq 0 tx-frames-irq 0 pkt-rate-low 0 pkt-rate-high 0
*
gives this output :
*adaptive-rx unmodified, ignoring *
*adaptive-tx unmodified, ignoring *
*pkt-rate-low unmodified, ignoring *
*pkt-rate-high unmodified, ignoring *
*rx-frames unmodified, ignoring *
*rx-usecs-irq unmodified, ignoring *
*rx-frames-irq unmodified, ignoring *
*tx-usecs unmodified, ignoring *
*tx-frames unmodified, ignoring *
*tx-usecs-irq unmodified, ignoring *
*tx-frames-irq unmodified, ignoring *
any other things I can try ?
Thank you very much...
Best Regards
Pier
On 11/04/14 09:32, Martin Troxler wrote:
Hi Pier,
On 10.04.2014 14:12, pier wrote:
What you write works only with the realtime kernel... ?
No, but you will certainly discover other latency effects.
We are using the Standard Ubuntu Kernel
The application runs under a Software Interrupt at 1.5 or 2 milliseconds...
we measured that it may have around 100 microseconds variation... ( Do you
call it Jitter ? )
For how long did you run cyclictest and with what cpu/disk load? For tips see
https://rt.wiki.kernel.org/index.php/RT_PREEMPT_HOWTO
I am certain that you will get latencies > 10ms sooner or later with a "normal"
kernel.
So this is ok for our control application....
Our app runs with 4kHz.
I did not know that the realtime kernel it's a must for etherlab...
It is not a must. But your realtime task will not run smooth.
When sometimes ago I tried to use the Realtime kernel from the Ubuntu Repository
the size of the video screen was limited to 1024*768 and we cannot use the
1920*1080
screen resolution for the Graphic Application and Video that we have.
Also there was another restriction that now I do not recall now....
We use Ubuntu 12.04 LTS as you do, but with our own kernel (3.6 or 3.10 at the
moment) built from sources and it works
as with the default Ubuntu kernel
Do you think that the : Working counter changed to 0/113
( that may happens once every 2 or 3 hours )
Ok. That's not very often.
it's because we use the standard kernel ?
Probably.
Is the realtime kernel the only solution ?
I would give it a try.
Regards
Martin
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