[linux-audio-dev] mpu401 fifo scheduling on linux2.4.18

Bruce M Beach brucemartinbeach at 21cn.com
Sat Nov 23 08:30:00 UTC 2002

On Fri, 22 Nov 2002, Frank van de Pol wrote:
> The timer frequency I was refering to is the linux kernel scheduling
> frequency, ie. the (asm/param.h) HZ constant. Since of 2.5 kernel it is
> increased from 100 tot 1000 btw.
   Ah.. I thought you were refering to something in the alsa drivers,
   which was why I was puzzled. I tried changeing the default value
   of 100 hz to 1024 hz and then 2048 hz and they both worked fine with
   the kernel supplied 'cmpci mpu401' driver(ie. solve the problem).
   Probably the 2048 hz was better. There is something wrong with the
   ALSA 'cmpci mpu401' driver, as it seems to drop bytes.

   I reverted back to 100 hz to test your welcome suggestion of cards
   with good transmission characteristics of which I found an old
   Ensonic AudioPCI. It worked very well making the above questions
   on scheduling academic since it has the needed interrupts and
   a fifo so the card is a keeper, although I did revert back to 1024 hz
   for the kernel scheduler since I like it better. Thanks for you help.
   Now I can get back to writing that korg patch editor.


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