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authorEric Dumazet <dada1@cosmosbay.com>2009-05-01 12:05:06 -0400
committerDavid S. Miller <davem@davemloft.net>2009-05-01 12:05:06 -0400
commitec581f6a42bbbea5271c66da9769a41b46c74e10 (patch)
tree608636f6519789f3504fd4d0077568cc25d89b5a
parent7a67e56fd362d3edfde1f19170893508c3940d3a (diff)
net: Fix skb_tx_hash() for forwarding workloads.
When skb_rx_queue_recorded() is true, we dont want to use jash distribution as the device driver exactly told us which queue was selected at RX time. jhash makes a statistical shuffle, but this wont work with 8 static inputs. Later improvements would be to compute reciprocal value of real_num_tx_queues to avoid a divide here. But this computation should be done once, when real_num_tx_queues is set. This needs a separate patch, and a new field in struct net_device. Reported-by: Andrew Dickinson <andrew@whydna.net> Signed-off-by: Eric Dumazet <dada1@cosmosbay.com> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--net/core/dev.c9
1 files changed, 5 insertions, 4 deletions
diff --git a/net/core/dev.c b/net/core/dev.c
index 308a7d0c277f..e2e9e4af3ace 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -1735,11 +1735,12 @@ u16 skb_tx_hash(const struct net_device *dev, const struct sk_buff *skb)
1735{ 1735{
1736 u32 hash; 1736 u32 hash;
1737 1737
1738 if (skb_rx_queue_recorded(skb)) { 1738 if (skb_rx_queue_recorded(skb))
1739 hash = skb_get_rx_queue(skb); 1739 return skb_get_rx_queue(skb) % dev->real_num_tx_queues;
1740 } else if (skb->sk && skb->sk->sk_hash) { 1740
1741 if (skb->sk && skb->sk->sk_hash)
1741 hash = skb->sk->sk_hash; 1742 hash = skb->sk->sk_hash;
1742 } else 1743 else
1743 hash = skb->protocol; 1744 hash = skb->protocol;
1744 1745
1745 hash = jhash_1word(hash, skb_tx_hashrnd); 1746 hash = jhash_1word(hash, skb_tx_hashrnd);