diff options
Diffstat (limited to 'drivers/net/virtio_net.c')
| -rw-r--r-- | drivers/net/virtio_net.c | 16 |
1 files changed, 12 insertions, 4 deletions
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index 59b0e9754ae3..63c7810e1545 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -749,9 +749,9 @@ static int virtnet_poll(struct napi_struct *napi, int budget) { struct receive_queue *rq = container_of(napi, struct receive_queue, napi); - unsigned int r, received = 0; + unsigned int r, received; - received += virtnet_receive(rq, budget - received); + received = virtnet_receive(rq, budget); /* Out of packets? */ if (received < budget) { @@ -939,8 +939,16 @@ static netdev_tx_t start_xmit(struct sk_buff *skb, struct net_device *dev) skb_orphan(skb); nf_reset(skb); - /* Apparently nice girls don't return TX_BUSY; stop the queue - * before it gets out of hand. Naturally, this wastes entries. */ + /* If running out of space, stop queue to avoid getting packets that we + * are then unable to transmit. + * An alternative would be to force queuing layer to requeue the skb by + * returning NETDEV_TX_BUSY. However, NETDEV_TX_BUSY should not be + * returned in a normal path of operation: it means that driver is not + * maintaining the TX queue stop/start state properly, and causes + * the stack to do a non-trivial amount of useless work. + * Since most packets only take 1 or 2 ring slots, stopping the queue + * early means 16 slots are typically wasted. + */ if (sq->vq->num_free < 2+MAX_SKB_FRAGS) { netif_stop_subqueue(dev, qnum); if (unlikely(!virtqueue_enable_cb_delayed(sq->vq))) { |