Re: [Xen-devel] Interrupt Affinity Question

[Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>]

On 14/4/07 04:33, "Pradeep Vincent" <pradeep.vincent@xxxxxxxxx> wrote:

> If dom-0 vcpu to pcpu affinity is not set (dom0_vcpus_pin not set),
> what happens when dom-0 vcpu migrates - is the  processor affinity of
> the irq channels changed by some means to reflect the migration  or do
> the hardware interrupts end up going to the old processor while the
> pirq will be served by the dom-0 vcpu on a different processor ?

This doesn't happen right now. What we may need to do is measure the cost of
needing to forward the interrupt to the correct CPU, in the case that the
VCPU is currently running on a different CPU, versus the cost of
reprogramming an IOAPIC register. Also important is to know how rapidly the
credit scheduler is moving VCPUs among CPUs, and hence the average number of
interrupts between movements.

 -- Keir



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