On 07/06/2012 04:02 AM, Amos Kong wrote:

On 07/05/2012 06:29 PM, Jason Wang wrote:

quoted

This patch converts virtio_net to a multi queue device. After negotiated
VIRTIO_NET_F_MULTIQUEUE feature, the virtio device has many tx/rx queue pairs,
and driver could read the number from config space.

The driver expects the number of rx/tx queue paris is equal to the number of
vcpus. To maximize the performance under this per-cpu rx/tx queue pairs, some
optimization were introduced:

- Txq selection is based on the processor id in order to avoid contending a lock
   whose owner may exits to host.
- Since the txq/txq were per-cpu, affinity hint were set to the cpu that owns
   the queue pairs.

Signed-off-by: Krishna Kumar<redacted>
Signed-off-by: Jason Wang<jasowang@redhat.com>
---

...

quoted

  static int virtnet_probe(struct virtio_device *vdev)
  {
-	int err;
+	int i, err;
  	struct net_device *dev;
  	struct virtnet_info *vi;
+	u16 num_queues, num_queue_pairs;
+
+	/* Find if host supports multiqueue virtio_net device */
+	err = virtio_config_val(vdev, VIRTIO_NET_F_MULTIQUEUE,
+				offsetof(struct virtio_net_config,
+				num_queues),&num_queues);
+
+	/* We need atleast 2 queue's */

s/atleast/at least/

quoted

+	if (err || num_queues<  2)
+		num_queues = 2;
+	if (num_queues>  MAX_QUEUES * 2)
+		num_queues = MAX_QUEUES;

                 num_queues = MAX_QUEUES * 2;

MAX_QUEUES is the limitation of RX or TX.

Right, it's a typo, thanks.

quoted

+
+	num_queue_pairs = num_queues / 2;

...