[libvirt-users] network-performance

[Daniel P. Berrange]

On Tue, Feb 01, 2011 at 02:33:28PM -0500, Brian K. White wrote:
> On 2/1/2011 12:39 PM, Orion Poplawski wrote:
> >I'm just starting to take a look at guest networking performance and am
> >a little disappointed. I'm comparing two setups:
> >
> >Host: Windows Server 2008 R2 Hyper-V
> >Guest: CentOS 5.5 x86_64
> >
> >Host: CentOS 5.5 x86_64 kvm running libvirt
> >Guest: CentOS 5.5 x86_64
> >
> >The guests are essentially identical except that I'm running the
> >Microsoft Linux Integration Components synthetic drivers on the windows
> >hosted VM. The libvirt setup uses bridged networking. Running bonnie++
> >on a nfs mounted filesystem on each guest I'm seeing the libvirt hosted
> >guest get between 16%-35% of the performance of the Hyper-V guest. Is
> >this expected? Is there anything I can do to increase network
> >performance of the kvm guest?
> >
> 
> First thing is to stop unfairly comparing things that don't even
> claim to do the same job. hyper-v is a hypervisor, while kvm is not,
> xen is.
> It would be closer but still unfair, to compare qemu or virtualbox
> for windows to kvm.

This distinction is completely irrelevant FUD. It is perfectly
valid to compare Hyper-V, Xen, KVM, VMWare and VirtualBox all
together, regardless of fact that they have different architectures.
They are all hypervisors, simply different types of hypervisor and
none of their architectures are inherantly "best", merely different.
For the only industry standard virtualization benchmark (SpecVirt),
KVM has the leading figures beating VMWare. This demonstrates the
KVM architecture is more than a match for the classical hypervisor
model of VWMare/Xen.

> You didn't say what kind of networking is being used wth hyper-v,
> but it's an understood fact that bridgeing in linux is easy to use
> and less efficient than routing or vlan or macvlan.
> 
> So I guess the answer is use xen and something other than bridging.

Both Xen and KVM use the Linux hosting for network connectivity,
so anything you can do with Xen networking you can do with KVM.
KVM in fact has more options because it can use macvtap which
isn't available to Xen yet.

Regards,
Daniel