Re: [Xenomai-help] gigabit rate packet processing with xenomai

[Jan Kiszka <jan.kiszka@domain.hid>]

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emin ak wrote:
> Dear All;
> Thanks for the answers firstly.
> I'am using linux (and also xenomai ) for a powerpc (PQ3/MPC8540) and
> will use on chip gigabit ethernet controller (tsec) that is not
> supported on rt-net yet (maybe untill I'll write one:)
> In my opinion and my basic tests shows that context switch times and
> system call latecies in linux decrease user space performance
> significally even with highest RT_FIFO priority and this reasons
> prevent my gigabit rate data processing in user space.
> I think I'll firstly choose un-deterministical way, write a realtime
> user space thread that process the data coming from linux ethernet
> driver, if it fails, I'll adapt the driver for rt-net or wait for the
> up-coming realtime-preemptive patch.

If you can live with a certain amount of deadline misses, this is
probably the most reasonable approach. And preempt-rt will further
improve the quality of service but will still not be able to /guarantee/
networking latencies (the network stack is not explicitly included in
the latency improvements under preempt-rt, resource allocation remains
nondeterministic).

Jan


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