Re: [OT] ALSA userspace API complexity

Jaroslav Kysela
2006-01-10T09:43:44Z

On Fri, 6 Jan 2006, Hannu Savolainen wrote:

> On Thu, 5 Jan 2006, Lee Revell wrote:
>
> > On Fri, 2006-01-06 at 01:06 +0200, Hannu Savolainen wrote:
> > > We have not received any single bug report that is caused
> > > by the concept of kernel mixing.
> > > Kernel mixing is not rocket science. All you need to do is picking a
> > > sample from the output buffers of each of the applications, sum them
> > > together (with some volume scaling) and feed the result to the
> > > physical
> > > device.
> >
> > Hey, interesting, this is exactly what dmix does in userspace. And we
> > have not seen any bug reports caused by the concept of userspace mixing
> > (just implementation bugs like any piece of software).
> Having dmix working in user space doesn't prove that kernel level mixing
> is evil. This was the original topic.

Overloading interrupt handlers with extra things is evil (and I bet you're
mixing samples in the interrupt handler). Even the network stack uses
interrupts only for DMA management and not for any extra operations.

Jaroslav

-----
Jaroslav Kysela <perex@suse.cz>
Linux Kernel Sound Maintainer
ALSA Project, SUSE Labs