I had a server running kvm that was upgraded from ubuntu 13.10 to 14.04 and since the upgrade after a couple of hours (in some cases less) the guest machines (a mix of linux and windows, using both virtio, realtek and intel as network interfaces), start to have network problems.
Pinging them shows that now and then the ping goes from a couple of miliseconds to several seconds. Also when connected to the guest using virt-manager when the ping goes through the roof the guest connection also freezes, although pinging the host never goes over 10ms.
I already tried several things: change network interface type (virtio, etc), pinning vcpus, adding <driver name='qemu'/>
to the guests' config, disable and reenable the guest network and even upgrading the packages using this ppa:ubuntu-virt/virt-daily-upstream
, but only rebooting the guest temporally solves this.
Any ideas? I am considering going back to 13.10.