[LAD] Timing of the ALSA loop device

[Robin Gareus]

On 03/21/2012 02:32 PM, Fons Adriaensen wrote:
> Hello,
> 
> Does anyone know what sort of timer is used by the ALSA
> loop device, and if this can be changed in some way ?

It uses the software clock (jiffies). It also has separate timers for
playback and capture and AFAICT it can not be changed.

Maybe you should ask on the alsa-dev list or read for yourself:
http://git.alsa-project.org/?p=alsa-kernel.git;a=blob;f=sound/drivers/aloop.c

> On the system I'm working on now,  wakeup times while waiting
> for a period to be available (as done by Jack and zita-alsa-pcmi)
> seem to be quantised in steps of 3.3ms or so. Which means it
> sometimes wakes up 3/4 or more of a period too late. Next one
> will be xrun in that case.
> 
> Ciao,
>