[linux-audio-user] USX2Y rawusb mode

Rui Nuno Capela rncbc at rncbc.org
Thu Mar 3 12:05:03 EST 2005

> Rui said a while ago that he was getting a similar message, until
> he tuned the IRQ priorities, but I've been googling around and I
> can't figure out how to do it. I tried
> chrt -f -p 90 'pidof "IRQ 0"'
> as directed on some website, but it just returns
> execvp: No such file or directory
> failed to execute pidof "IRQ 0"

When I said that I was assuming that you have Ingo Molnar's
realtime-preempt patch, which applies to vanilla 2.6 kernels only (latest
is 2.6.11-rc4). The patch is here:
You can only do that IRQ tunning if you have this kernel configured with
PREEMPT_RT=y (i.e. complete realtime-preemption enabled).

Once you have this up and running, tune the IRQ threads (with chrt) like
this example:

  timer:  chrt -f -p 90 `pidof "IRQ 0"`
  rtc:    chrt -f -p 80 `pidof "IRQ 8"`
  snd:    chrt -f -p 70 `pidof "IRQ 5"`
  usb:    chrt -f -p 60 `pidof "IRQ 10"`

Please note you must check which IRQ numbers are the appropriate (cat
/proc/interrupts); the above is just an example taken from my laptop,
where the USB controller (ohci_hcd) is on IRQ 10 and the onboard sound is
on IRQ 5. YMMV.

rncbc aka Rui Nuno Capela
rncbc at rncbc.org

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