Alex, Thanks for your reply, and i will check it agiain with msi-x. YiLi 2012/11/27 Alex Williamson <alex.williamson@xxxxxxxxxx>: > 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
