mapping interrupts to a particular cpu

Alfred Perlstein alfred at freebsd.org
Thu Feb 1 03:33:57 UTC 2007


Through source inspection it appears that we don't have interrupts
running in the context of the actual interrupt handler unless they
are truly "FAST".  (correct me if I'm wrong).

That makes my decision a lot easier.  I will just use bind_cpu.

If so, I will just use bind_cpu.

* Alfred Perlstein <alfred at freebsd.org> [070131 19:18] wrote:
> [[jhb cc'd cause he's Mr Apic from what I understand.]]
> 
> I'm trying to figure out pinning interrupts to a particular cpu.
> 
> If it can be done, if it's worth it and how.
> 
> Any generic pointers one could give to help me do this?  I'd like to
> bind network interfaces to a particular cpu.
> 
> I guess the questions boil down to:
> 
> 1) Are we at the point that an interrupt for something such as an
>    ethernet device actually runs under interrupt context?  
>    (or do we always switch to an ithread (for !FAST_INTR))
>    (I already know about bind_cpu which can be done inside interrupt
>     routine (I think?))
> 
> Anyhow, if we have the actual interrupts running directly...
> 2) How can I bind an interrupt source to a cpu?
> 3) Is there a way to determine which cpu is best to wire an interrupt to?
> 


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