Re: [PATCH net-next 3/3] virtio-net: change the number of queuesthrough ethtool

From: Michael S. Tsirkin
Date: Tue Dec 04 2012 - 08:47:18 EST


On Tue, Dec 04, 2012 at 07:07:58PM +0800, Jason Wang wrote:
> This patch implement the ethtool_{set|get}_channels method of ethool to allow
> user to change the number of queues dymaically when the device is running. This
> would let the user to configure it on demand.
>
> Signed-off-by: Jason Wang <jasowang@xxxxxxxxxx>
> ---
> drivers/net/virtio_net.c | 44 ++++++++++++++++++++++++++++++++++++++++++++
> 1 files changed, 44 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 912f5b2..b9f9887 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -1589,10 +1589,54 @@ static struct virtio_driver virtio_net_driver = {
> #endif
> };
>
> +/* TODO: Eliminate OOO packets during switching */
> +static int virtnet_set_channels(struct net_device *dev,
> + struct ethtool_channels *channels)
> +{
> + struct virtnet_info *vi = netdev_priv(dev);
> + u16 queue_pairs = channels->combined_count;
> + u16 old_queue_pairs = vi->curr_queue_pairs;
> +
> + /* We don't support separate rx/tx channels.
> + * We don't allow setting 'other' channels.
> + */
> + if (channels->rx_count || channels->tx_count || channels->other_count)
> + return -EINVAL;
> +
> + if (queue_pairs > vi->max_queue_pairs)
> + return -EINVAL;
> +
> + vi->curr_queue_pairs = queue_pairs;
> + if (virtnet_set_queues(vi) == 0) {
> + netif_set_real_num_tx_queues(dev, vi->curr_queue_pairs);
> + netif_set_real_num_rx_queues(dev, vi->curr_queue_pairs);

Just use queue_pairs - it's shorter.

> +
> + virtnet_set_affinity(vi, true);
> + } else
> + vi->curr_queue_pairs = old_queue_pairs;

Should be
ret = virtnet_set_queues(vi);
if (ret) {
vi->curr_queue_pairs = old_queue_pairs;
return ret;
}
otherwise we loose error reporting.

Also it's better if virtnet_set_queues
gets queue_pairs as parameter and set curr_queue_pairs
on success.

> +
> + return 0;
> +}
> +
> +static void virtnet_get_channels(struct net_device *dev,
> + struct ethtool_channels *channels)
> +{
> + struct virtnet_info *vi = netdev_priv(dev);
> +
> + channels->combined_count = vi->curr_queue_pairs;
> + channels->max_combined = vi->max_queue_pairs;
> + channels->max_other = 0;
> + channels->rx_count = 0;
> + channels->tx_count = 0;
> + channels->other_count = 0;
> +}
> +
> static const struct ethtool_ops virtnet_ethtool_ops = {
> .get_drvinfo = virtnet_get_drvinfo,
> .get_link = ethtool_op_get_link,
> .get_ringparam = virtnet_get_ringparam,
> + .set_channels = virtnet_set_channels,
> + .get_channels = virtnet_get_channels,
> };
>
> static int __init init(void)
> --
> 1.7.1
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/