Re: [RFC PATCH v2 15/19] kvm: add dynamic IRQ support

From: Gregory Haskins
Date: Mon Apr 13 2009 - 13:45:20 EST


Avi Kivity wrote:
>>
>
> Given that you're using the apic to inject the IRQ, you'll need an
> EOI. So what's the difference between dynirq and MSI, performance wise?
>

I would have loved to eliminate that EOI completely, but that is a much
broader problem to solve ;)

Actually dynirq wasnt introduced as a performance alternative over MSI.
Rather, I was trying to eliminate the complexity of needing to sync
between the userspace PCI emulation and the in kernel models.

However, its moot. Since v2 introduce virtio-vbus, I now have a much
clearer picture of what is needed here, and v3 will simply integrate
with MSI interrupts and drop dynirq completely. So please ignore this
patch.

-Greg


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