[PlanetCCRMA] need advice on optimizing IRQ for sound
Mark Knecht
markknecht@comcast.net
Mon Aug 30 14:37:01 2004
On Mon, 2004-08-30 at 11:35, Louis Lam wrote:
> 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.
OK, so according to the manual for this motherbaord IRQ's 10 and 11 are
'User Available'. (Page 54) Page 56 shows how the PIRQ's are routed on
the motherboard. I think if it was me (and it isn't!) I might try the
audio card in PCI Slot 5 as that slot has IRQA support and is apparently
shared with only an onboard USB UHCI device. (PIRQC)
Another options would be PCI Slot 2 which appears to have INTA support
without sharing. (PIRQG)
It looks like this would work pretty well as long as none of your other
cards (if you have any) generate more than one interrupt output.
Once I had the card in slot two or slot 5 (As numbered from closest to
the AGP connector being PCI Slot 1) then I'd use BIOS to set the
interrupt for the slot I put the card in to IRQ10 or IRQ11. (Assuming
I'm given those options.)
You're lucky that Intel does good manuals, like Via. this was about 5
minutes worth of effort. Took more time to write it down.
>
> 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.
There is no great advantage of IRQ3 over IRQ7. I would not disable USB
jsut to do that.
> 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?
I'll defer to others due to your use of the word 'advisable'.
>
> 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?
I think you do have options, but a little bit of work is required to get
there.
>
> 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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