Re: CONFIG_IRQBALANCE for AMD64?

[Nick Piggin]

Andi Kleen wrote:

> And handling all interrupts at CPU #0 during early boot up is 
> not really an issue.
>
> An kernel implementation may make sense when you're doing something
> really dynamic: e.g. not just a timer, but dynamically redirecting
> network interrupts to the CPU the process who will read from the
> socket runs on. Obviously it would need kernel support for that, since
> user space could not keep up with such a high sampling rate. But that's
> future research work (if it can be even done generically at all)
> and I don't see it on the radar screen anytime soon. We first need to solve
> the NUMA scheduling problem, which is already hard enough ;-) 

We're actually doing the converse of this in the sched-domain
scheduler. Processes have a tendancy to follow the interrupts
(ie. try to get onto the same CPU as them).

This makes good interrupt balancing important.

I have a feeling it might be best to keep the interrupts on
the closest CPUs, and move processes to match. Or possibly a
mix of both approaches.
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