Re: [RFC] Virtual Machine Device Queues(VMDq) support on KVM

From: Stephen Hemminger
Date: Mon Sep 21 2009 - 12:21:48 EST


On Mon, 21 Sep 2009 16:37:22 +0930
Rusty Russell <rusty@xxxxxxxxxxxxxxx> wrote:

> > > Actually this framework can apply to traditional network adapters which have
> > > just one tx/rx queue pair. And applications using the same user/kernel interface
> > > can utilize this framework to send/receive network traffic directly thru a tx/rx
> > > queue pair in a network adapter.
> > >

More importantly, when virtualizations is used with multi-queue NIC's the virtio-net
NIC is a single CPU bottleneck. The virtio-net NIC should preserve the parallelism (lock
free) using multiple receive/transmit queues. The number of queues should equal the
number of CPUs.
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