Il 05/05/22 15:05, Jan Kiszka ha scritto:
On 03.05.22 17:18, Mauro S. via Xenomai wrote:
Hi all,
I'm trying to use RTNet with TDMA.
I succesfully set up my bus:
- 1GBps speed
- 3 devices
- cycle time 1ms
- timeslots with 200us offset
I wrote a simple application that in parallel receives and sends UDP
packets on TDMA bus.
- sendto() is done to the broadcast address, port 1111
- recvfrom() is done on the port 1111
Application sends a small packet (5 bytes) in a periodic task with 1ms
period and prio 51. Receive is done in a non-periodic task with prio 50.
Application is running on all the three devices, and I can see packets
are sent and received correctly by all the devices.
But after a while, all send() calls on all devices fails with error EAGAIN.
Could this error be related to some internal buffer/queue that becomes
full? Or am I missing something?
When you get EAGAIN on sender side, cleanup of TX buffers likely failed,
and the socket ran out of buffers to send further frames. That may be
related to TX IRQs not making it. Check the TX IRQ counter on the
sender, if it increases at the same pace as you send packets.
Jan
Thanks Jan for your fast answer.
I forgot to mention that I'm using the rt_igb driver.
I have only one IRQ field in /proc/xenomai/irq, counting both TX and RX
cat /proc/xenomai/irq | grep rteth0
125: 0 0 2312152 0 rteth0-TxRx-0
I did this test:
* on the master I send a packet every 1ms in a periodic RT task (period
1ms, prio 51) with my test app.
* on the master I see an increment of about 2000 IRQs per second: I
guess 1000 are for my sent packets (1 packet every ms), and 1000 for the
TDMA sync packet. In fact I see the "rtifconfig" RX counter almost
stationary (only 8 packets every 2-3 seconds, refresh requests from
slaves?), TX counter incrementing in about 2000 packets per second.
* on the two slaves (thet are running nothing) I observe the same rate
(about 2000 IRQs per second). I see the "rtifconfig" TX counter almost
stationary (only 4 packets every 2-3 seconds), RX counter incrementing
in about 2000 packets per second.
* if I stop sending packets with my app, I can see all the rates at
about 1000 per second
If I start send-receive on all the three devices, I can see a IRQ rate
around 4000 IRQs per second on all devices (1000 sync, 1000 send and
1000 + 1000 receive).
I observed that if I only send from master and receive on slaves the
problem does not appear. Or if I send/receive from all, but with a
packet every 2ms, the problem does not appear.
Could be a CPU performance problem (4k IRQs per second are too much for
an Intel Atom x5-E8000 CPU @ 1.04GHz)?
Thanks in advance, regards
--
Mauro S.
