Messages in this thread | | | Subject | RE: [patch 1/1] Proposed: Let's not waste precious IRQs... | Date | Fri, 20 May 2005 12:27:09 -0500 | From | "Protasevich, Natalie" <> |
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> > Hi Natalie, > > On Thu, 19 May 2005 Natalie.Protasevich@unisys.com wrote: > > > I suggest to change the way IRQs are handed out to PCI devices. > > Currently, each I/O APIC pin gets associated with an IRQ, > no matter if > > the pin is used or not. It is expected that each pin can > potentually > > be engaged by a device inserted into the corresponding PCI slot. > > However, this imposes severe limitation on systems that > have designs > > that employ many I/O APICs, only utilizing couple lines of > each, such > > as P64H2 chipset. It is used in ES7000, and currently, > there is no way > > to boot the system with more that 9 I/O APICs. The simple > change below > > allows to boot a system with say 64 (or more) I/O APICs, each > > providing 1 slot, which otherwise impossible because of the > IRQ gaps > > created for unused lines on each I/O APIC. It does not resolve the > > problem with number of devices that exceeds number of > possible IRQs, > > but eases up a tension for IRQs on any large system with > potentually > > large number of devices. I only implemented this for the ACPI boot, > > since if the system is this big and > > Can you determine number of slots in use?
I think it is possible, but then it will probably be back to something like "pci=routeirq" philosophy.
> > using newer chipsets it is probably (better be!) an ACPI based > > system :). The change is completely "mechanical" and does not alter > > any internal structures or interrupt model/implementation. > The patch > > works for both i386 and x86_64 archs. It works with MSIs just fine, > > and should not intervene with implementations like shared vectors, > > when they get worked out and incorporated. > > Well we ran into similar problems on older MPS systems > (NUMAQ) but those don't really matter right now anyway. So i > think fixing this for ACPI is fine.
ACPI is well organized and easily manipulated, that's why I stopped right there. I tried adjusting the MPS case, it is possible, but then I thought no one would need it anyway. It would take multiple changes and won't be pretty, but if you insist I can work it out :) > But i like your patch =)
:)
> Thanks, > Zwane > > - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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