On Tue, 2012-11-27 at 00:47 +0800, yi li wrote: > hi Alex, > > the qemu-kvm version 1.2. And is the device making use of MSI-X or MSI interrupts. MSI-X should work on 1.2, MSI does not yet support vector updates for affinity, but patches are welcome. Thanks, Alex > 2012/11/26 Alex Williamson <alex.williamson@xxxxxxxxxx>: > > 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
