kvm-owner@xxxxxxxxxxxxxxx wrote on 10/06/2012 13:16:01: > > Yep, these are corner cases we should deal with but they are not part > > of the common case/critical path. > > > >> I'm wondering if redirecting (to different cores) or masking (at > >> device/IOAPIC/LAPIC level) of non-guest interrupts and only relying on > >> preemption timer/NMI isn't simpler. Then you wouldn't have to shadow the > >> IDT. > > > > Yep, as we suggested in the paper, that could be also an alternative. > > Is it really simpler ? Again, depends who you ask and what you need to > > change. > > All the alternatives have a set of pros and cons. > > > For sure. But avoiding the shadow IDT would likely mean avoiding > userspace changes for KVM. And that means simplification. And avoid PCI > dependencies. But you lose flexibility. Remember that if you don't shadow the IDT you need at least one dedicated core that never uses ELI to handle all the physical interrupts. With the shadow IDT, you could enable ELI in all the cores. In addition, if you don't use the shadow IDT, host interrupts will not be balanced across all the ELI cores. Thus, if you run many VMs/VCPU, you might experience higher latency/bottlenecks or have scalability problems unless you use a shadow IDT (depending on the workload, offcourse). -- 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
