[Xenomai] RtNet and Interrupts

Norbert Lange nolange79 at gmail.com
Fri Feb 17 13:04:17 CET 2017


2017-02-17 12:47 GMT+01:00 Mariusz Janiak <mariuszjaniak at wp.pl>:
> Dnia Piątek, 17 Lutego 2017 12:19 Norbert Lange <nolange79 at gmail.com> napisał(a)
> *snip*
>
> Maybe author of the RTnet stack can give better answer, but in my opinion, in the case of the hard RT communication, we have to know in advance what is the maximum packet delivery time. The RTnet guarantee fixed time packet delivery. There is always a trad off between bandwidth and latency, you can't have both.

Sure, but there is also "low latency" and "guaranteed latency", the
later is affected and hard to prove if you can`t bound eg. the IRQs to
a specific maximum.
Hmm, probably an issue though, as the RtNet Protocol wants to
synchronize clocks as well. We have synchronized clocks via a
dedicated PPS wire, so we wouldn`t need that.
Using PTP Hardware could probably fix that.

>
>> No efforts in using something similar to "New API"? (who comes up with
>> such names...)
>
> I remember a discussion about NAPI in context of  RTnet stack, but I don't know if any attempts have been made.

Ok, any way to search the mailing list, havent found any?

> *snip*
>
> Unfortunately I can't help.

No prob.

Kind regards, Norbert



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