Re: What determines which interrupts are shared under Linux?
From: linux-os (Dick Johnson)
Date: Tue Aug 15 2006 - 11:16:49 EST
On Tue, 15 Aug 2006, Roger Heflin wrote:
> On Linux when interrupts are defined similar to below, what defines say
> ide2, ide3 to be on the same interrupt? The bios, linux, the driver using
> the interrupt? And can that be controlled/overrode at the
> kernel/driver level?
> I have identified that the disks that are shared on ide2, ide3 do funny
> things when both are being heavily used (dma_expiry), this is an older
> driver versions
> but I have experienced it before with a lot newer driver, and a bios
> previously fixed a similar issue, so that may be what is needed in this
> case also,
> I am not sure how they fixed it, but I suspect that the setup the interrupt
> to not be shared. I have a large number of machines and under heavy
> loads all
> seem to duplicate the issue, and it always happens with the disks on
> never on the disk connected to ide4.
> CPU0 CPU1 CPU2 CPU3
> 0: 56616921 5359998 7002142 938817 XT-PIC timer
> 1: 8 88 96 0 IO-APIC-edge i8042
> 2: 0 0 0 0 XT-PIC cascade
> 4: 2091 100 208 2477 IO-APIC-edge serial
> 8: 0 0 0 0 IO-APIC-edge rtc
> 9: 0 0 0 0 IO-APIC-level acpi
> 20: 0 0 0 0 IO-APIC-level ehci_hcd
> 21: 0 950 401419 414482 IO-APIC-level ide4,
> 22: 1165 1704243 576247 6796 IO-APIC-level ide2,
> 47: 65971 0 0 0 IO-APIC-level eth0
> NMI: 1 1 1 1
> LOC: 69904264 69877733 69879541 69901903
> ERR: 0
> MIS: 105
The hardware defines what traces go to whatever chips on the
motherboard and to the feature module sockets. Sometimes,
the ultimate IRQ that these traces go to can be configured in the
BIOS. Sometimes not. The kernel just uses what was set up by
the BIOS, convention, and the PCI devices themselves.
Penguin : Linux version 22.214.171.124 on an i686 machine (5592.62 BogoMips).
New book: http://www.AbominableFirebug.com/
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