On Fri, 06 Jul 2012 11:20:06 +0800
Jason Wang [off-list ref] wrote:

On 07/05/2012 08:51 PM, Sasha Levin wrote:

quoted

On Thu, 2012-07-05 at 18:29 +0800, Jason Wang wrote:

quoted

@@ -1387,6 +1404,10 @@ static int virtnet_probe(struct virtio_device *vdev)
         if (virtio_has_feature(vdev, VIRTIO_NET_F_CTRL_VQ))
                 vi->has_cvq = true;

+       /* Use single tx/rx queue pair as default */
+       vi->num_queue_pairs = 1;
+       vi->total_queue_pairs = num_queue_pairs;

The code is using this "default" even if the amount of queue pairs it
wants was specified during initialization. This basically limits any
device to use 1 pair when starting up.

Yes, currently the virtio-net driver would use 1 txq/txq by default 
since multiqueue may not outperform in all kinds of workload. So it's 
better to keep it as default and let user enable multiqueue by ethtool -L.

I would prefer that the driver sized number of queues based on number
of online CPU's. That is what real hardware does. What kind of workload
are you doing? If it is some DBMS benchmark then maybe the issue is that
some CPU's need to be reserved.