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| author | David S. Miller <davem@davemloft.net> | 2009-05-03 14:43:10 -0700 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2009-05-03 14:43:10 -0700 |
| commit | 513de11bba246b7a67df4c314d9fc936b6a75d0e (patch) | |
| tree | 773f446b9a609e771ff75ebd9bfacd4d3d52f99f /net/core/dev.c | |
| parent | accc5b4f902b0ba83b2c6c48f2d9e7c204cef4a8 (diff) | |
| download | lwn-513de11bba246b7a67df4c314d9fc936b6a75d0e.tar.gz lwn-513de11bba246b7a67df4c314d9fc936b6a75d0e.zip | |
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
larger.
Therefore, a subtraction loop is always going to be faster than
modulus.
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/core/dev.c')
| -rw-r--r-- | net/core/dev.c | 8 |
1 files changed, 6 insertions, 2 deletions
diff --git a/net/core/dev.c b/net/core/dev.c index 81442957c5c2..3c8073fe970a 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -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; |