diff options
| -rw-r--r-- | drivers/net/virtio_net.c | 14 |
1 files changed, 9 insertions, 5 deletions
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index a829930dac15..63c7810e1545 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -939,11 +939,15 @@ static netdev_tx_t start_xmit(struct sk_buff *skb, struct net_device *dev) skb_orphan(skb); nf_reset(skb); - /* It is better to stop queue if running out of space - * instead of forcing queuing layer to requeue the skb - * by returning TX_BUSY (and cause a BUG message). - * Since most packets only take 1 or 2 ring slots - * this means 16 slots are typically wasted. + /* 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); |