[alsa-devel] [RFC] disabling ALSA period interrupts

Clemens Ladisch clemens at ladisch.de
Fri Apr 30 13:24:13 CEST 2010

pl bossart wrote:
> When PulseAudio is used and all PCM is routed through PulseAudio
> (Fedora, Meego, etc), the notion of ALSA periods isn't very useful.
> So why not disable them entirely to reduce the number of wakeups? ...
> There are probably some cases where you don't want this type of
> behavior (broken hardware, legacy code with multiple-buffering,
> disabled timer in PulseAudio),

It's interesting that all ALSA applications except PA are "legacy".  :)

> so I think it would make sense to request the disabling of interrupts
> when hw_params are set, since this is also the time when period sizes
> are set.

Yes.  For compatibility with the existing ALSA API, this needs to be
a flag that is not enabled by default.

> I am aware that some changes would be needed in pcm_lib.c, where all
> the error checks are done.

Plus all the API changes in the ALSA kernel framework, the ALSA kernel/
userspace interface, and the alsa-lib interface.

I'll see if I can get this done over the weekend ...


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