Re: [Qemu-devel] Using virtio-net and vhost_net on an ARM machine using qemu-system-arm & KVM

[Ying-Shiuan Pan <yingshiuan.pan@gmail.com>]

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Hi, Barak,

We've tried vhost-net in kvm-arm on arndale Exynos-5250 board (it requires
some patches in qemu and kvm, of course). It works (without irqfd support),
however, the performance does not increase much. The throughput (iperf) of
virtio-net and vhost-net are 93.5Mbps and 93.6Mbps respectively. I thought
the result are because both virtio-net and vhost-net almost reached the
limitation of 100Mbps Ethernet.

The good news is that we even ported vhost-net in our kvm-a9 hypervisor
(refer:
http://academic.odysci.com/article/1010113020064758/evaluation-of-a-server-grade-software-only-arm-hypervisor),
and the throughput of vhost-net on that platform (with 1Gbps Ethernet)
increased from 323Mbps to 435Mbps.

--
Ying-Shiuan Pan,
H Div., CCMA, ITRI, TW


----
Best Regards,
潘穎軒Ying-Shiuan Pan


2014/1/13 Peter Maydell <peter.maydell@linaro.org>

> On 12 January 2014 21:49, Barak Wasserstrom <wbarak@gmail.com> wrote:
> > Thanks - I got virtio-net-device running now, but performance is
> terrible.
> > When i look at the guest's ethernet interface features (ethtool -k eth0)
> i
> > see all offload features are disabled.
> > I'm using a virtual tap on the host (tap0 bridged to eth3).
> > On the tap i also see all offload features are disabled, while on br0 and
> > eth3 i see the expected offload features.
> > Can this explain the terrible performance i'm facing?
> > If so, how can this be changed?
> > If not, what else can cause such bad performance?
> > Do you know if vhost_net can be used on ARM Cortex A15 host/guest, even
> > though the guest doesn't support PCI & MSIX?
>
> I have no idea, I'm afraid. I don't have enough time available to
> investigate performance issues at the moment; if you find anything
> specific you can submit patches...
>
> thanks
> -- PMM
>
>

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