Re: emulating gigabit ethernet

[Dor Laor <dor.laor-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

Wes wrote:
> Hello List,
>
> Are there any plans on emulating gigabit under qemu/kvm? 
>
> I ask because at the moment networking in guests on an ibm x3650 host 
> is embarrassingly slow.  Using model=rtl8139 results in max of 12% of 
> bandwidth utilisation @ 100mbit (which in practice equates to 10mbit 
> performance), and using the default model=ne2k_pci results in much 
> faster albeit still sub-100mbit performance (while reporting 10mbit in 
> the guest).  Is this something that can be worked around?  Since the 
> x3650's we use here have 2 gigabit ports, is it possible to pass one 
> to the guest for direct access instead of being forced to emulate a 
> nic then route via 8021q and tun/tap?
It's weird the rtl gives worse performance than ne2k, it should be the 
opposite. What kvm version do you test?
Try test with the latest (Avi added a small tap performance 
improvement.) If this does not help try
to add the -no-kvm-irqchip flag to the party.

Regarding pci pass through, we have a prototype working which will be 
release soon (month).
Dor.

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