On Tue, Nov 13, 2012 at 06:22:56PM +0200, Michael S. Tsirkin wrote: > On Tue, Nov 13, 2012 at 12:49:03PM +0100, Peter Lieven wrote: > > > > On 09.11.2012 19:03, Peter Lieven wrote: > > >Remark: > > >If i disable interrupts on CPU1-3 for virtio the performance is ok again. > > > > > >Now we need someone with deeper knowledge of the in-kernel irqchip and the > > >virtio/vhost driver development to say if this is a regression in qemu-kvm > > >or a problem with the old virtio drivers if they receive the interrupt on > > >different CPUs. > > anyone? > > Looks like the problem is not in the guest: I tried ubuntu guest > on a rhel host, I got 8GB/s with vhost and 4GB/s without > on a host to guest banchmark. >
Tried with upstream qemu on rhel kernel and that's even a bit faster. So it's ubuntu kernel. vanilla 2.6.32 didn't have vhost at all so maybe their vhost backport is broken insome way. > > > > > > > > >Peter Lieven wrote: > > >>it seems that with in-kernel irqchip the interrupts are distributed across > > >>all vpcus. without in-kernel irqchip all interrupts are on cpu0. maybe > > >>this is related. > > >> > > >>without inkernel irqchip > > >> CPU0 CPU1 CPU2 CPU3 > > >> 0: 16 0 0 0 IO-APIC-edge > > >> timer > > >> 1: 23 0 0 0 IO-APIC-edge > > >> i8042 > > >> 4: 1 0 0 0 IO-APIC-edge > > >> 6: 4 0 0 0 IO-APIC-edge > > >>floppy > > >> 7: 0 0 0 0 IO-APIC-edge > > >>parport0 > > >> 8: 0 0 0 0 IO-APIC-edge rtc0 > > >> 9: 0 0 0 0 IO-APIC-fasteoi acpi > > >> 11: 76 0 0 0 IO-APIC-fasteoi > > >>uhci_hcd:usb1 > > >> 12: 102 0 0 0 IO-APIC-edge > > >> i8042 > > >> 14: 0 0 0 0 IO-APIC-edge > > >>ata_piix > > >> 15: 16881 0 0 0 IO-APIC-edge > > >>ata_piix > > >> 24: 0 0 0 0 PCI-MSI-edge > > >>virtio1-config > > >> 25: 5225 0 0 0 PCI-MSI-edge > > >>virtio1-requests > > >> 26: 0 0 0 0 PCI-MSI-edge > > >>virtio0-config > > >> 27: 72493 0 0 0 PCI-MSI-edge > > >>virtio0-input > > >>... > > >> > > >>with inkernel irqchip > > >> CPU0 CPU1 CPU2 CPU3 > > >> 0: 16 0 0 0 IO-APIC-edge > > >> timer > > >> 1: 0 3 3 1 IO-APIC-edge > > >> i8042 > > >> 4: 0 0 1 0 IO-APIC-edge > > >> 6: 1 0 1 2 IO-APIC-edge > > >>floppy > > >> 7: 0 0 0 0 IO-APIC-edge > > >>parport0 > > >> 8: 0 0 0 0 IO-APIC-edge rtc0 > > >> 9: 0 0 0 0 IO-APIC-fasteoi acpi > > >> 11: 7 9 4 1 IO-APIC-fasteoi > > >>uhci_hcd:usb1 > > >> 12: 30 27 29 34 IO-APIC-edge > > >> i8042 > > >> 14: 0 0 0 0 IO-APIC-edge > > >>ata_piix > > >> 15: 943 937 950 943 IO-APIC-edge > > >>ata_piix > > >> 24: 0 0 0 0 PCI-MSI-edge > > >>virtio0-config > > >> 25: 930 978 980 947 PCI-MSI-edge > > >>virtio0-input > > >> 26: 0 0 1 0 PCI-MSI-edge > > >>virtio0-output > > >> 27: 0 0 0 0 PCI-MSI-edge > > >>virtio1-config > > >> 28: 543 541 542 553 PCI-MSI-edge > > >>virtio1-requests > > >>... > > >> > > >> > > >
