I use a RME Digi 96 PAD audio card, and I do have buffer overrun/underrun problems if I use the standard rme96c linux driver.
I need a simple recording machine. It should not fail if e.g. cron starts updatedb or if I start a make -j 15 icecream compile job and decide to surf the internet while I record the digital satellite radio 48kHz stream.
There is a lot of information about xrun problems, but somehow that information either does not help to prevent xruns on my system, is outdated, or asks for system changes I do not accept.
No, JACK does not help. No, I do not need low latency. No, I don't want to switch to rt kernels. No, I don't want to use an audio PC without X, without cron, network, etc.
The hardware provides independent 64k ringbuffers for capture and playback, that's not more than 85msec for a 96 kHz / 2 channel / 32 bit setup or ADAT. That's simply not enough for reliable operation.
My private solution is a rme96.c that kmallocs 4 MB software buffers for capture and playback, data transfer between software and hardware buffer in the interrupt service routine. That does efficiently prevent xruns even on a really loaded system.
But I don't know if that is the right way to go.
Wouldn't it be better if there would be an (optional) software buffer one layer above the hardware driver? That would increase reliability for all audio hardware with insufficient hardware buffers.
Is there any other audio hardware with similar small buffers?
Has somebody already written an "extended alsa buffer" patch? Did I miss something?
To put it into one question: How much buffer should be provided by an alsa hardware driver module?
cu, Knut