On 12.04.2012 09:42, Hans-Kristian Bakke wrote: > Hi > > For some reason I am not able to get good network performance using > virtio/vhost-net on Debian KVM host (perhaps also valid for Ubuntu > hosts then). > Disc IO is very good and the guests feels snappy so it doesn't seem > like there is something really wrong, just something suboptimal with > the networking. [......] > I have tried: > ---------------- > - Replacing Debian Wheezy with Debian Squeeze (stable, kernel > 2.6.32-xx) - even worse results > - Replacing kernel 3.2.0-2-amd64 with vanilla kernel 3.4-rc2 and > config based on Debians included config - no apparent change > - Extracted the kernel-config file from Fedora 17 alphas kernel and > used this to compile a new kernel based on Debian Wheezys kernel > source - slightly worse results > - ...in addition to exchanging Debian with Fedora 17 alpha, Proxmox > 1.9 and 2.0 and ESXi 5 which all have expected network performance > using virtio. > > > So, I am at a loss here. I does not seem to be kernel config related > (as using Fedoras config on Debian kernel source didn't do anything > good) so I think it must be either a kernel patch that red hat kernel > based distros uses to make virtio/vhost much more efficient or perhaps > something with Debians qemu-version, bridging or something. I have made some tests with a Debian Squeeze KVM host running with the Linux Kernel 2.6.39 from backports and the Kernel version 2.6.32-11-pve from Proxmox. (http://download.proxmox.com/debian/dists/squeeze/pve/binary-amd64/pve-kernel-2.6.32-11-pve_2.6.32-66_amd64.deb) Network performance between two virtual machines on the same host is significantly slower with the Debian kernel: 2.6.39-bpo.2-amd64 : 1.31 Gbits/sec 2.6.32-11-pve : 2.20 Gbits/sec iperf tests between a virtual machine and the KVM host connected to the same local bridge interface showed similar results. Are there other people who can confirm this? Regards, Stefan -- 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
