Re: [Qemu-devel] slow virtio network with vhost=on and multiple cores

[Dietmar Maurer]

> > ./x86_64-softmmu/qemu-system-x86_64 -smp sockets=1,cores=2 -m 512 -
> hda
> > debian-squeeze-netinst.raw -netdev
> > type=tap,id=net0,ifname=tap111i0,vhost=on -device
> > virtio-net-pci,netdev=net0,id=net0
> >
> > Downloading a larger file with wget inside the guest will show the problem.
> Speed drops from 100MB/s to 15MB/s.
> >
> > Can someone reproduce that bug? Any ideas how to fix that?
> 
> Which exact QEMU are you using: qemu or qemu-kvm?  Distro package or
> from source?  Any patches applied?

I just tested with latest sources from git://git.qemu-project.org/qemu.git

./x86_64-softmmu/qemu-system-x86_64 -smp sockets=1,cores=2 -m 512 -hda 
debian-squeeze-netinst.raw -netdev type=tap,id=net0,ifname=tap111i0,vhost=on 
-device virtio-net-pci,netdev=net0,id=net0 --enable-kvm

got incredible bad performance  - can't you reproduce the problem?