Lock-free dmix considered harmful

[Jaroslav Kysela]

Dne 19. 05. 20 v 15:46 Takashi Iwai napsal(a):
> 
>> Because of these reasons I think it would be better to drop the lock-free implementation entirely and just use the existing non-concurrent architecture-independent implementation from pcm_dmix_generic.c. Aside from being faster, it would also eliminate a lot of architecture-dependent code and inline assembly. Should I submit a patch for this?
> 
> The advantage of lockless dmix implementation isn't about its CPU usage
> but the nature where a stream isn't prevented by other streams, which
> assures the very low latency, too.  That is, with the generic dmix, a
> stream can be still halted when another stream stalls in the middle,
> and there is no way to recover from it.
> 
> So, IMO, we can start with a dynamic configuration to choose the
> behavior and add a configure option to choose the implementations.
> The default behavior should be still an open question, though.

I fully agree here.

					Jaroslav

-- 
Jaroslav Kysela <perex at perex.cz>
Linux Sound Maintainer; ALSA Project; Red Hat, Inc.