Re: [Qemu-devel] QEMU -netdev vhost=on + -device virtio-net-pci bug

[Alexey Kardashevskiy]

On 10/03/13 20:24, Michael S. Tsirkin wrote:
> On Fri, Mar 08, 2013 at 03:48:04PM +1100, Alexey Kardashevskiy wrote:
> > Michael,
> >
> > Thanks for the fix.
> >
> > There was another question which was lost in the thread.
> >
> > I am testing virtio-net in two ways:
> >
> > Old -net interface:
> > -net tap,ifname=tap0,script=qemu-ifup.sh \
> > -net nic,model=virtio,addr=0:0:0
> >
> > (qemu) info network
> > hub 0
> >   \ virtio-net-pci.0:
> > index=0,type=nic,model=virtio-net-pci,macaddr=52:54:00:12:34:56
> >   \ tap.0: 
> > index=0,type=tap,ifname=tap0,script=qemu-ifup.sh,downscript=/etc/qemu-ifdown
> >
> > New -netdev interface:
> > -netdev tap,id=tapnet,ifname=tap0,script=qemu-ifup.sh \
> > -device virtio-net-pci,netdev=tapnet,addr=0.0
> >
> > (qemu) info network
> > virtio-net-pci.0:
> > index=0,type=nic,model=virtio-net-pci,macaddr=52:54:00:12:34:56
> >   \ tapnet: 
> > index=0,type=tap,ifname=tap0,script=qemu-ifup.sh,downscript=/etc/qemu-ifdown
> >
> >
> > I get very different virtio0 device features and speed (70MB/s vs.
> > 700MB/s). I guess somehow the "hub 0" is responsible but there is no
> > way to avoid it.
> >
> > Is there any way to speed up the virtio-net using the old -net interface?
>
> Not at the moment. Why do you want to use it?


It is not like I really want it, I was just trying to understand (now it is
more or less clear) why exactly "not" as the documentation is saying about 
-net and -netdev as synonyms while they are not.



--
Alexey