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Date: Thu, 29 Jan 2009 14:05:57 -0800
Message-ID: <74ae4f6a0901291405o6b615399vaa033abfbeac3a06@mail.gmail.com>
Subject: Re: x86_64 IOAPIC
From: SUJIT V <sujit.linux@gmail.com>
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Forgot to mention that we are not using the irqbalance utility.

So which part of the kernel io_apic code is doing the irq balancing
which we see in /proc/interrupt.

Thanks


On Thu, Jan 29, 2009 at 2:02 PM, SUJIT V <sujit.linux@gmail.com> wrote:
> Hi,
>    We have a IBM Qauadcore 8 CPU system running x86_64 linux 2.6.23.
> We were doing some performance test. (disk & network).
> The eth0 IRQ is pinned to CPU0.  The aacraid interrupt has not been
> assigned any smp affinity.
>
> On the system we see in (/proc/interrupts) that when the eth0
> interrupt rate is high, the aacraid interrupt counter for CPU0 does
> not increase as much compared to aacraid interrupts handled by other
> CPUs .
> This shows that IOAPIC is doing some load balancing.
>
> I wanted to check the code which is doing this load balancing. I
> checked the file arch/x86_64/kernel/io_apic.c. I could not find any
> irq balancing stuff out there.
> I went through some archived discussions about the x86_64 ioapic irq
> balancing. Most of the discussions were about using irqbalance
> utility.
>
>
> Could some one point me to the relevant piece of io_apic code ?
>
>
> Thanks
>