Re: Virtio network performance poorer than emulated e1000

[Sebastian Hetze <s.hetze@linux-ag.com>]

I did some benchmarking mainly with tbench and found virtio better
with big packages/maximum throughput and e1000 better with small
packages/latency. vhost-net improves virtio quite a lot and makes
it superior to the emulated devices.

If network performance is a real issue, DMAR/IOMMU gives you direct
access to dedicated network devices with nearly 100% native throughput
and latency.

Best regards,

  Sebastian

On Thu, Jul 22, 2010 at 04:13:29PM -0400, Balachandar wrote:
> I can see that virtio network performance is poorer than emaulated
> e1000 nic. I did some simple ping test and with emulated e1000 the
> average rtt is around 600 microsec. With virtio the average rtt is 800
> microsec. I am using a tap + bridge configuration. I run kvm as
> follows
> 
> kvm -m 512 -hda vdisk.img \
> -net nic,model=virtio \
> -net tap,ifname=tap0,script=qemu-ifup,downscript=no
> 
> I am running Debian squeeze distribution with guest and host kernel 2.6.34.
> 
> Does anyone else see some results like this or is it only me? Could
> changing the distribution help as i am running a testing one?
> 
> Thanks,
> Bala