Re: irq load balancing

kalash nainwal
2007-09-12T11:56:14Z

On 9/12/07, Venkat Subbiah <venkats@cranite.com> wrote:
> Most of the load in my system is triggered by a single ethernet IRQ. Essentially the IRQ schedules a tasklet and most of the work is done in the taskelet which is scheduled in the IRQ. From what I read looks like the tasklet would be executed on the same CPU on which it was scheduled. So this means even in an SMP system it will be one processor which is overloaded.
>
> So will using the user space IRQ loadbalancer really help? What I am doubtful about is that the user space load balance comes along and changes the affinity once in a while. But really what I need is every interrupt to go to a different CPU in a round robin fashion.
>
> Looks like the APIC can distribute IRQ's dynamically? Is this supported in the kernel and any config or proc interface to turn this on/off.
>

/proc/irq/<irq#>/smp_affinity. But this is not generally suggested for
performance reasons (cache issues etc).

>
> Thx,
> Venkat
>
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