Commit 513de11b authored by David S. Miller's avatar David S. Miller

net: Avoid modulus in skb_tx_hash() for forwarding case.

Based almost entirely upon a patch by Eric Dumazet.

The common case is to have num-tx-queues <= num_rx_queues
and even if num_tx_queues is larger it will not be significantly

Therefore, a subtraction loop is always going to be faster than
Signed-off-by: default avatarDavid S. Miller <>
parent accc5b4f
......@@ -1735,8 +1735,12 @@ u16 skb_tx_hash(const struct net_device *dev, const struct sk_buff *skb)
u32 hash;
if (skb_rx_queue_recorded(skb))
return skb_get_rx_queue(skb) % dev->real_num_tx_queues;
if (skb_rx_queue_recorded(skb)) {
hash = skb_get_rx_queue(skb);
while (unlikely (hash >= dev->real_num_tx_queues))
hash -= dev->real_num_tx_queues;
return hash;
if (skb->sk && skb->sk->sk_hash)
hash = skb->sk->sk_hash;
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