Hello RT community,
I'm _not_ going to ask the question again:
'Is it possible to do TCP/IP from an RTL module?'
though mine probably is a dummies one as well.
I tried to follow the advice given many times: trigger a user space
helper (I'm using /dev/rtf0). My helper thread blocks on reading
a byte written by a RTAI module ervery 20ms and then sends some data.
My aim is to send a udp broadcast as closely bound to that trigger as
possible. Jitter would be well acceptable up to 1+ ms. I assumed to
achieve that by setting the helper thread to SCHED_RR with a high
priority (e.g. 99).
But I find this construct working quite precise only most of the time:
The reception of single triggers (as measured by timestamps from user
space, with the RT activity known to be precise) is delayed by up to
15 ms. These runaways are not really constant but seem to happen in
some repetitive patterns, the most obvious with a ~1.2sec period.
There is no (obvious) load on system, disk or network and I'm not aware
of any other high prio activities potentially delaying me.
Please could somebody give a hint where to look, what to do better or
(hopefully not) that my expectations are too high.
Thanks a lot
Wilken Boie
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