On 10/09/2018 05:41 PM, Shannon Nelson wrote:
> From: Silviu Smarandache <silviu.smaranda...@oracle.com>
>
> This patch modifies the RPS processing code so that it searches
> for a matching vlan interface on the packet and then uses the
> RPS settings of the vlan interface. If no vlan interface
> is found or the vlan interface does not have RPS enabled,
> it will fall back to the RPS settings of the underlying device.
>
> In supporting VMs where we can't control the OS being used,
> we'd like to separate the VM cpu processing from the host's
> cpus as a way to help mitigate the impact of the L1TF issue.
> When running the VM's traffic on a vlan we can stick the Rx
> processing on one set of cpus separate from the VM's cpus.
> Yes, choosing to use this may cause a bit of throughput pain
> when the packets are actually passed into the VM and have to
> move from one cache to another.
>
> Orabug: 28645929
>
> Signed-off-by: Silviu Smarandache <silviu.smaranda...@oracle.com>
> Signed-off-by: Shannon Nelson <shannon.nel...@oracle.com>
> ---
> net/core/dev.c | 59
> +++++++++++++++++++++++++++++++++++++++++++++++++++++++---
> 1 file changed, 56 insertions(+), 3 deletions(-)
>
> diff --git a/net/core/dev.c b/net/core/dev.c
> index 0b2d777..1da3f63 100644
> --- a/net/core/dev.c
> +++ b/net/core/dev.c
> @@ -3971,8 +3971,8 @@ set_rps_cpu(struct net_device *dev, struct sk_buff *skb,
> * CPU from the RPS map of the receiving queue for a given skb.
> * rcu_read_lock must be held on entry.
> */
> -static int get_rps_cpu(struct net_device *dev, struct sk_buff *skb,
> - struct rps_dev_flow **rflowp)
> +static int __get_rps_cpu(struct net_device *dev, struct sk_buff *skb,
> + struct rps_dev_flow **rflowp)
> {
> const struct rps_sock_flow_table *sock_flow_table;
> struct netdev_rx_queue *rxqueue = dev->_rx;
> @@ -4066,6 +4066,35 @@ static int get_rps_cpu(struct net_device *dev, struct
> sk_buff *skb,
> return cpu;
> }
>
> +static int get_rps_cpu(struct net_device *dev, struct sk_buff *skb,
> + struct rps_dev_flow **rflowp)
> +{
> + /* Check for a vlan device with RPS settings */
> + if (skb_vlan_tag_present(skb)) {
> + struct net_device *vdev;
> + u16 vid;
> +
> + vid = skb_vlan_tag_get_id(skb);
> + vdev = __vlan_find_dev_deep_rcu(dev, skb->vlan_proto, vid);
> + if (vdev) {
> + /* recorded queue is not referring to the vlan device.
> + * Save and restore it
> + */
> + int cpu;
> + u16 queue_mapping = skb_get_queue_mapping(skb);
> +
> + skb_set_queue_mapping(skb, 0);
> + cpu = __get_rps_cpu(vdev, skb, rflowp);
> + skb_set_queue_mapping(skb, queue_mapping);
This is really ugly :/
Also what makes vlan so special compared to say macvlan ?
