On Fri, 2012-11-23 at 11:06 +0800, yi li wrote: > Hi Guys, > > there have a issue about smp_affinity cannot work correctly on guest > os when PCI passthrough device using msi/msi-x with KVM. > > My reason: > pcpu will occur a lot of ipi interrupt to find the vcpu to handle the > irq. so the guest os will VM_EXIT frequelty. right? > > if smp_affinity can work correctly on guest os, the best way is that > the vcpu handle the irq is cputune at the pcpu which handle the > kvm:pci-bus irq on the host.but unfortunly, i find that smp_affinity > can not work correctly on guest os when msi/msi-x. > > how to reproduce: > 1: passthrough a netcard (Brodcom BCM5716S) to the guest os > > 2: ifup the netcard, the card will use msi-x interrupt default, and close the > irqbalance service > > 3: echo 4 > cat /proc/irq/NETCARDIRQ/smp_affinity, so we assume the vcpu2 > handle the irq. > > 4: we have set <vcpupin vcpu='2' cpuset='1'/> and set the irq kvm:pci-bus to > the pcpu1 on the host. > > we think this configure will reduce the ipi interrupt when inject interrupt to > the guest os. but this irq is not only handle on vcpu2. maybe it is > not our expect。 What version of qemu-kvm/qemu are you using? There's been some work recently specifically to enable this. Thanks, Alex -- 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
