Re: vhost + multiqueue + RSS question.

["Michael S. Tsirkin" <mst@redhat.com>]

On Sun, Nov 16, 2014 at 06:18:18PM +0200, Gleb Natapov wrote:
> Hi Michael,
> 
>  I am playing with vhost multiqueue capability and have a question about
> vhost multiqueue and RSS (receive side steering). My setup has Mellanox
> ConnectX-3 NIC which supports multiqueue and RSS. Network related
> parameters for qemu are:
> 
>    -netdev tap,id=hn0,script=qemu-ifup.sh,vhost=on,queues=4
>    -device virtio-net-pci,netdev=hn0,id=nic1,mq=on,vectors=10
> 
> In a guest I ran "ethtool -L eth0 combined 4" to enable multiqueue.
> 
> I am running one tcp stream into the guest using iperf. Since there is
> only one tcp stream I expect it to be handled by one queue only but
> this seams to be not the case. ethtool -S on a host shows that the
> stream is handled by one queue in the NIC, just like I would expect,
> but in a guest all 4 virtio-input interrupt are incremented. Am I
> missing any configuration?

I don't see anything obviously wrong with what you describe.
Maybe, somehow, same irqfd got bound to multiple MSI vectors?
To see, can you try dumping struct kvm_irqfd that's passed to kvm?


> --
> 			Gleb.