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mikezackles

Member

Registered: 2007-09-23

Posts: 41

jackd xruns (wifi irq conflict???)

/etc/security/limits.conf:

*               -       rtprio          0
*               -       nice            0
@audio          -       rtprio          99
@audio          -       nice           -15
@audio          -       memlock         400000

cat /proc/interrupts

           CPU0       
  0:    3435857   IO-APIC-edge      timer
  1:       6999   IO-APIC-edge      i8042
  8:          0   IO-APIC-edge      rtc0
  9:      28017   IO-APIC-fasteoi   acpi
 12:     309292   IO-APIC-edge      i8042
 14:      63717   IO-APIC-edge      libata
 15:     108125   IO-APIC-edge      libata
 16:     422243   IO-APIC-fasteoi   wifi0, ohci1394
 17:     906900   IO-APIC-fasteoi   uhci_hcd:usb4, yenta, Indigo IO, i915@pci:0000:00:02.0
 18:          0   IO-APIC-fasteoi   uhci_hcd:usb3, tifm_7xx1, eth0
 19:          0   IO-APIC-fasteoi   uhci_hcd:usb2, sdhci:slot0
 20:        367   IO-APIC-fasteoi   HDA Intel
 21:          0   IO-APIC-fasteoi   uhci_hcd:usb1, ehci_hcd:usb5
NMI:          0 
LOC:     542456 
ERR:          0
MIS:          0

qjackctl executes the following on jackd startup:

chrt -f -p 89 `pidof "jackd"`

I'm using an Echo Indigo IO on a satellite a135-s4656.
With wireless disabled, kernel26rt (2.6.21.rt8) from proaudio repo gives no xruns with 64 frames/period.
With wireless enabled, kernel26rt gives plenty of xruns.
vanilla kernel gives xruns both ways...
Is there a way to swap IRQs between wifi and the card slot?
Any ideas??  Is acpi an issue?  I need the wireless enabled because I'm trying to collaborate by routing Ardour through Skype.

mikezackles

Member

Registered: 2007-09-23

Posts: 41

Re: jackd xruns (wifi irq conflict???)

Duplicated on an ubuntu-studio installation.  Everything works great without wireless.

mikezackles

Member

Registered: 2007-09-23

Posts: 41

Re: jackd xruns (wifi irq conflict???)

So I finally figured this out... The following page was enlightening:
http://tapas.affenbande.org/wordpress/?page_id=6
I guess the vanilla kernel is a regular preemptible kernel without threads for hard irqs?
Anyway, the following worked for me with the real-time kernel:

chrt -f -p 99 `pidof "IRQ-17"`

I had tried this before with the vanilla kernel, but I was confused because I couldn't find a pid for any IRQ process.  I didn't realize that this had to do with what type of kernel I was running.
Anyway, everything works great now (jackd running with a priority of 75), even with compiz fusion cranked up!