Re: [net-next rfc v7 2/3] virtio_net: multiqueue support

Rusty Russell
2012-12-03T02:04:08Z

Jason Wang <jasowang@redhat.com> writes:
> +static const struct ethtool_ops virtnet_ethtool_ops;
> +
> +/*
> + * Converting between virtqueue no. and kernel tx/rx queue no.
> + * 0:rx0 1:tx0 2:cvq 3:rx1 4:tx1 ... 2N+1:rxN 2N+2:txN
> + */
> +static int vq2txq(struct virtqueue *vq)
> +{
> + int index = virtqueue_get_queue_index(vq);
> + return index == 1 ? 0 : (index - 2) / 2;
> +}
> +
> +static int txq2vq(int txq)
> +{
> + return txq ? 2 * txq + 2 : 1;
> +}
> +
> +static int vq2rxq(struct virtqueue *vq)
> +{
> + int index = virtqueue_get_queue_index(vq);
> + return index ? (index - 1) / 2 : 0;
> +}
> +
> +static int rxq2vq(int rxq)
> +{
> + return rxq ? 2 * rxq + 1 : 0;
> +}
> +

I thought MST changed the proposed spec to make the control queue always
the last one, so this logic becomes trivial.

> +static int virtnet_set_queues(struct virtnet_info *vi)
> +{
> + struct scatterlist sg;
> + struct virtio_net_ctrl_rfs s;
> + struct net_device *dev = vi->dev;
> +
> + s.virtqueue_pairs = vi->curr_queue_pairs;
> + sg_init_one(&sg, &s, sizeof(s));
> +
> + if (!vi->has_cvq)
> + return -EINVAL;
> +
> + if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_RFS,
> + VIRTIO_NET_CTRL_RFS_VQ_PAIRS_SET, &sg, 1, 0)){
> + dev_warn(&dev->dev, "Fail to set the number of queue pairs to"
> + " %d\n", vi->curr_queue_pairs);
> + return -EINVAL;
> + }

Where do we check the VIRTIO_NET_F_RFS bit?

> static int virtnet_probe(struct virtio_device *vdev)
> {
> - int err;
> + int i, err;
> struct net_device *dev;
> struct virtnet_info *vi;
> + u16 curr_queue_pairs;
> +
> + /* Find if host supports multiqueue virtio_net device */
> + err = virtio_config_val(vdev, VIRTIO_NET_F_RFS,
> + offsetof(struct virtio_net_config,
> + max_virtqueue_pairs), &curr_queue_pairs);
> +
> + /* We need at least 2 queue's */
> + if (err)
> + curr_queue_pairs = 1;

Huh? Just call this queue_pairs. It's not curr_ at all...

> + if (virtio_has_feature(vdev, VIRTIO_NET_F_CTRL_VQ))
> + vi->has_cvq = true;
> +
> + /* Use single tx/rx queue pair as default */
> + vi->curr_queue_pairs = 1;
> + vi->max_queue_pairs = curr_queue_pairs;

See...

Cheers,
Rusty.