Re: irq balancing question

[Arjan van de Ven <arjan@infradead.org>]

On Fri, 2007-02-23 at 13:32 +0200, Imre Gergely wrote:
> hi
> 
> i have a SMP with 2x duo-core Opteron processors, and i have an ethernet card
> (eth0). i want to balance the interrupts generated by the card to all 4
> processors. 

you have only one card? then balancing like you say will only really
hurt you; neither linux nor the chipset will do this.

> is this irq balancing a feature in the chipset, or driver, or kernel ? i got
> the idea of the smp_affinity stuff, and i've set it to "f", but nothing
> happens, i mean i see only one CPU getting the interrupts.

if you have multiple real interrupt sources you can balance between them
using irqbalance, see http://www.irqbalance.org
But note that this program will NOT move one irq across 4 cpus all the
time, since that gives *really* bad performance.

-- 
if you want to mail me at work (you don't), use arjan (at) linux.intel.com
Test the interaction between Linux and your BIOS via http://www.linuxfirmwarekit.org

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