[64studio-devel] Interrupts and stuff

[Michael Jarosch]

Hi!

Got a problem on an ASUS A8V Deluxe / AMD Athlon 64 3000+ / RME HDSP 
9652 -System. I can see, that this or similar combination is often used 
for sound-producing and I read lots about people, working with latencies 
under 2ms without getting xruns. Well I'm using 10 ms latency, but xruns 
appear from time to time, anyway.
Looking at my interrupts, it seems quite clear, why:

mitsch at 64studio:~$ cat /proc/interrupts
           CPU0
  0:        193   IO-APIC-edge      timer
  1:       1854   IO-APIC-edge      i8042
  5:          0   IO-APIC-edge      MPU401 UART
  8:          0   IO-APIC-edge      rtc
  9:          0   IO-APIC-fasteoi   acpi
 12:          4   IO-APIC-edge      i8042
 14:      21954   IO-APIC-edge      ide0
 16:     182052   IO-APIC-fasteoi   ohci1394, nvidia
 17:      72482   IO-APIC-fasteoi   eth0, hdsp
 18:          0   IO-APIC-fasteoi   libata
 20:      42601   IO-APIC-fasteoi   libata
 21:     110985   IO-APIC-fasteoi   uhci_hcd:usb1, uhci_hcd:usb2, 
uhci_hcd:usb3, ehci_hcd:usb4, uhci_hcd:usb5
 22:          0   IO-APIC-fasteoi   VIA8237
NMI:          0
LOC:    2476944
ERR:          0

My card (hdsp) is on IRQ 17, sharing it with the Ethernet-Port, now. 
After manually moving the soundcard from PCI-Slot to PCI-Slot I can 
summarize, that i can't get the soundcards IRQ below 16. Using 16 is a 
bad idea, since this IRQ is shared with the graphic-adapter + firewire. 
The only Interrupt that can be used solely is IRQ 19, far away from 
being the best configuration.
On the other hand, IRQ 10 and 11 are not used at all!?!
The BIOS of the ASUS Board doesn't allow to configure using a special 
Interrupt with a special PCI-Slot.

I read on a german audio-forum called audio4linux that there seems to be 
a kernel patch, allowing to assign an IRQ to a PCI-Slot. Is this patch 
already in the 64studio kernel? And if yes, how to use it?

Mitsch