virtio-net: per-queue RPS config

On multiqueue network devices, RPS maps are configured independently
for each receive queue through /sys/class/net/$DEV/queues/rx-*.

On virtio-net currently all packets use the map from rx-0, because the
real rx queue is not known at time of map lookup by get_rps_cpu.

Call skb_record_rx_queue in the driver rx path to make lookup work.

Recording the receive queue has ramifications beyond RPS, such as in
sticky load balancing decisions for sockets (skb_tx_hash) and XPS.

Reported-by: Mark Hlady <mhlady@google.com>
Signed-off-by: Willem de Bruijn <willemb@google.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 0237250..236ba5d 100644 (file)
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -1035,6 +1035,7 @@ static void receive_buf(struct virtnet_info *vi, struct receive_queue *rq,
                goto frame_err;
        }
 
+       skb_record_rx_queue(skb, vq2rxq(rq->vq));
        skb->protocol = eth_type_trans(skb, dev);
        pr_debug("Receiving skb proto 0x%04x len %i type %i\n",
                 ntohs(skb->protocol), skb->len, skb->pkt_type);