Messages in this thread | | | Subject | Re: balance interrupts | From | Julien Oster <> | Date | Mon, 08 Dec 2003 21:00:52 +0100 |
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Len Brown <len.brown@intel.com> writes:
Hello Len,
> Most IO-APIC systems have PCI interrupt lines hard-wired directly to > IO-APIC interrupt pins. If an interrupt isn't where you want it to be, > you need to physically move a card to another slot so that it gets a > different wire. A board with decent documentation will tell you what > slots get which interrupt wires.
Ah, my board has that kind of documentation. Well, then I might do just this - or see if my board can do that for me. Also, I'd really want to know if maybe I can split apart the two SATA channels.
> Today basically all boards have also a PIRQ router that is used to map > these PCI interrupt wires down into PIC interrupt inputs for when the > system is in PIC compatibility mode (eg. when running the booter). > Sometimes they can also re-map interrupt lines in IO-APIC mode.
Ah, that sounds interesting.
> Since your system is running in ACPI mode, the output of acpidmp is > needed to figure out exactly that the BIOS is saying the board can do. > The output of lspci -l with this will tell us if we can split apart the > SATA interrupts, or if they're wired together.
Hmm. I got pciutils 2.1.11 (those claim to be the latest), but my lspci doesn't know "-l". I attached the output of lspci -vvv to this mail, however. Maybe it's of any use.
I attached the output of acpidmp to this mail as well. It's a collection of hexdumps. Since I have no internal knowledge about ACPI or IO-APICs, I can't do anything with it...
> Another twist is that sometimes enabling/disabling devices in the BIOS > SETUP will change how the BIOS configures the hardware and make more > interrupts available. Here, for example, USB seems to be low hanging > fruit on a high-rent >= 16 IRQ.
Sorry, I didn't quite understand your last sentence with the fruits and the rent. I suppose it's some expression, but I'm not a native english speaker.
But I already disabled everything I don't need in the BIOS (I need USB, however) and the situation didn't improve very dramatically. At least I can't see of any devices having changed place in the IRQ list, only that the devices I deactivated have gone. I also enable "Reset ESCD data" in the BIOS to encourage things getting rearranged.
> If you're not using ACPI features, you might also try booting with > "acpi=off" and see if the chip-set PIRQ router does a better job for > you.
Hmm. If I remember correctly the IRQs stay XT-PIC if I don't enable ACPI, regardless wether IO-APIC is enabled or not. And the old style PIC of course leads to the result of my interrupts being very crowded...
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