ALSA problems
 

Hi all.
I've got a problem with my audio sound card when there is an high use of video or CPU.
For example, if I'm listening to an MP3 using any player and launch a command like "find /", the sound jerks. The problem stops if you hide the terminal window.
I've got the same problem using mplayer in fullscreen with an high-CPU video codec, like x264.
The game Battle for Wesnoth, which use SDL with ALSA output, produces many errors of "Buffer underrun", especially when I scroll the map.
There is no problem if I use OSS output.
I'm using 32bit Slackware current with kernel 2.6.38.8, rebuilt with all modules for fixed hardware in built-in. Also "radeon" module is in built-in with KMS enabled by default. On the contrary, ALSA is installed as module.
I'm using KDE 4.5.5.
Someone may help me?
Thanks in advice.

I was having similar problems with a custom 2.6.38.8(-zen) kernel and a 2.6.39.2(-zen) kernel (ALC268 on this lappie here), so I tried switching to the stock -generic kernel on current and that seems to have fixed things: I suspect some kind of regression (to say it all I think not even related directly to alsa) but I really cannot bisect on this hardware (it powers on successfully at random) so I'll play with -generic for a while. :)

Sorry... I forgot to say that I'm using a Dell Inspiron 9400 laptop, with a HDA Intel (SigmaTel STAC9200).
If I remember correctly, the problem started when I use for the first time Kernel ModeSetting with radeon... Maybe the two are related...

@ponce:
Do you think that it could be a kernel problem??
Tonight I'll try to update to 2.6.39 series.

I suggest you to try first with the -generic shipped with slackware ;)

I tried using kernel 2.6.39.2, and both huge-smp and generic-smp, with no results.
Then I tried to boot my kernel with radeon.modeset=0 (built-in radeon module) and the sound stops to jerk.
I tried without modeset also using generic and huge-smp, and no problems occured.
I've noticed that without modeset the whole system is slower than with. It's like a sort of priority system. With modeset, video takes precedence to audio, and without modeset audio takes precedence.
After that, I think that the problem is modeset... Perhaps in how modeset interact with my hardware...
Any solutions or ideas?

Thanks :)

Other people have the same problem:
https://bugtrack.alsa-project.org/al...ew.php?id=5408
http://www.linuxmusicians.com/viewtopic.php?f=6&p=20592

Most audio devices, that aren't a standalone peripheral based solution, are codec devices that utilize CPU power to process the audio. If you have an onboard audio solution, running anything that may require more system resources, like a file search, can affect things like audio processing at times and cause anything from stuttering to even complete stalls.

My laptop use an Intel HDA... SigmaTel Audio Codec 9200... STAC92xx...
Perhaps is a software-based audio card...

FYI, the issues I had disappeared with the 3.0 kernel (but no radeon or kms here).

Sigmatel codecs are software based. IDT, Realtek, Sigmatel, and SoundMAX all are codec and software based audio devices that use the Azalia (Intel HD Audio) foundation.

The only real hardware sound card/chip manufacturers anymore are M-Audio, C-Media, and Creative.