On Mon, Aug 13, 2012 at 02:03:51PM +0300, Avi Kivity wrote: > On 08/13/2012 02:01 PM, Gleb Natapov wrote: > >> > >> Actually this is overkill. Suppose we do an apicid->vcpu translation > >> cache? Then we retain O(1) behaviour, no need for a huge cache. > >> > > Not sure I follow. > > Unicast MSIs and IPIs can be speeded up by looking up the vcpu using the > apic id, using a static lookup table (only changed when the guest > updates apicid or a vcpu is inserted). > To check that MSI/IPI is unicast you need to check a lot of things: delivery mode, shorthand, dest mode, vector. In short everything but level. This is exactly what kvm_irq_delivery_to_apic() is doing. Caching apicid->vcpu is not enough, caching (delivery mode, shorthand, dest mode, vector)->vcpu is enough and this is exactly what the patch does for irq routing entries. -- Gleb. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
