[PlanetCCRMA] need advice on optimizing IRQ for sound

[Louis Lam]

Hi,

I managed to disable the acpi using "acpi=off"(its a desktop). For the IRQS though the best I
could  do was making the soundblaster card use IRQ3. 

I have an intel D875PBZ mainboard that has integrated usb and ethernet. The BIOS allows manual
setting of IRQs for each slot(5 altogether), but can't guarantee that you'll get the IRQs that you
intend to assign. Given the amount of onboard devices, no matter how I try to make the slot use a
particular IRQ, I just don't get it. This mainboard does not seem to have force ESCD so the only
way to change IRQ is to change slots. That didn't seem to work either(sometimes changing the slot
result in sharing of IRQ with another device like the USB!).

To get the soundcard to use IRQ3 that i mentioned earlier, I disabled the onboard USB devices.

I also happen to have DeMuDI installed on the same system. It seems to be using APIC, so the IRQ
for the sound card was on IRQ22. 

Q1: Is it advisable to use APIC for PlanetCCRMA kernel? 
  
Q2: At this point don't seem to have many options for me to get a higher priority IRQ like 9, any
other things I can do to improve that?

Thanks in Advance,
Louis
 --- Mark Knecht <markknecht@comcast.net> wrote: 
> On Mon, 2004-08-30 at 04:23, Louis Lam wrote:
> > Hi,
> > 
> > I'm trying to optimize the system for sound. Looking
> > through the "Tuning the System" part of the
> > installation part, I'm at the point where I'm looking
> > at the IRQs in the system.
> > 
> > I have the following when I look at /proc/interrupts:
> > 
> >           CPU0
> >   0:   22656444          XT-PIC  timer
> >   1:       5230          XT-PIC  keyboard
> >   2:          0          XT-PIC  cascade
> >   5:          0          XT-PIC  usb-uhci
> >   7:    2244442          XT-PIC  EMU10K1
> >   8:          1          XT-PIC  rtc
> >   9:          0          XT-PIC  acpi, ehci_hcd
> >  10:     255784          XT-PIC  usb-uhci, eth0
> >  11:          0          XT-PIC  usb-uhci, usb-uhci
> >  12:     299974          XT-PIC  PS/2 Mouse
> >  14:     152742          XT-PIC  ide0
> >  15:     180923          XT-PIC  ide1
> > NMI:          0
> > ERR:          0
> > 
> > Looks like one of the more obvious things to do is to
> > get the soundblaster card (emu10k1) to a higher
> > priority than 7(lowest). Looking at the list of
> > interrupts on the system I see the "acpi" using IRQ 9.
> > Is acpi necessary for a DAW to function? Say I'm using
> > this system mainly for ardour, rosegarden. Should this
> > be disabled?
> > 
> > Thanks,
> > Louis
> 
> I don't know much about the ACPI/APM stuff. If this is a desktop machine
> I'd just switch the sound b;aster and ethernet cards and you'll probably
> be OK. ACPI doesn't use many interrupts anyway, or so I've been told.
> 
> If this is a laptop then you are in a different kettle of fish...
> 
> Good luck,
> Mark
> > 
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