Re: [Xenomai-help] Communication between Xenomai and Linux domains

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

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van der Linden wrote:
> ...
> My real-time thread will call the alsa-sound library libasound and use the 
> ALSA Linux kernel driver for my sound card.

I many cases, audio processing is a soft real-time task: quality
decreases as latency increases, but the world won't stop turning. So
unless you have very tight latency requirements (can you specify them,
BTW?), you are probably better off with the -rt (or "PREEMPT-RT")
patches. They achieve quite low, but generally not guaranteed latencies
for wide areas of the Linux kernel, including its sound subsystem (the
Linux audio community is using those patches e.g.).

If this doesn't fly for you (because of too low or actually hard latency
requirements), you will have to audit the relevant ALSA code paths from
the library in user land down to the low-level driver, either improve
them for your scenario on -rt or port a required subset over to
Xenomai's RTDM driver model.

Xenomai as-is will not improve ALSA latencies. Rather, your thread will
leave the RT space managed by Xenomai when it starts talking to this layer.

Jan


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