Exceed 1GB/s with virtio-net ?

[Thibault VINCENT <thibault.vincent@smartjog.com>]

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Hello

I'm trying to achieve higher than gigabit transferts over a virtio NIC
with no success, and I can't find a recent bug or discussion about such
an issue.

The simpler test consist of two VM running on a high-end blade server
with 4 cores and 4GB RAM each, and a virtio NIC dedicated to the
inter-VM communication. On the host, the two vnet interfaces are
enslaved into a bridge. I use a combination of 2.6.35 on the host and
2.6.32 in the VMs.
Running iperf or netperf on these VMs, with TCP or UDP, result in
~900Mbits/s transferts. This is what could be expected of a 1G
interface, and indeed the e1000 emulation performs similar.

Changing the txqueuelen, MTU, and offloading settings on every interface
(bridge/tap/virtio_net) didn't improve the speed, nor did the
installation of irqbalance and the increase in CPU and RAM.

Is this normal ? Is the multiple queue patch intended to address this ?
It's quite possible I missed something :)

Thank you dear list !

-- 
Thibault VINCENT

SmartJog S.A.S. - Groupe TDF - Pôle multimédia
27 Bd Hippolyte Marques, 94200 Ivry sur Seine, France
Phone : +33.1.58.68.62.38
Fax   : +33.1.58.68.60.97


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