[LAD] 2.6.20 scheduler and buffer underruns

Darren Gibbs tsquank at yahoo.com
Wed Jul 11 19:26:32 UTC 2007


We're doing an ARM-based embedded device, which right now is running  
vanilla 2.6.20.  For the sake of simplicity we wrote an OSS driver  
that's simply double-buffering and writing to the DAC via I2S.  We  
have a buffer underrun problem that is directly proportional to CPU  
load... no glitches when simply cat-ing a file to /dev/dsp, but lots  
of glitches when other things are happening on the system.  Can  
anyone suggest tools/techniques/patches for improving the situation?   
Use an alternative scheduler?  Figure out which driver might be  
turning interrupts off for too long?  We're using 20ms buffers which  
seems pretty generous.

I know this is a bit of a noob question, but any advice or pointers  
to info much appreciated.

darren 



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