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| author | Eric Dumazet <eric.dumazet@gmail.com> | 2010-07-13 05:24:20 +0000 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2010-07-14 15:33:27 -0700 |
| commit | 87fd308cfc6b2e880bf717a740bd5c58d2aed10c (patch) | |
| tree | 15c27522669b08a6d26efbcd447abf3d78ad13fb /net | |
| parent | 3a047bf87b1b6f69c62ab9fb28072c639cb7e2fa (diff) | |
| download | lwn-87fd308cfc6b2e880bf717a740bd5c58d2aed10c.tar.gz lwn-87fd308cfc6b2e880bf717a740bd5c58d2aed10c.zip | |
net: skb_tx_hash() fix relative to skb_orphan_try()
commit fc6055a5ba31e2 (net: Introduce skb_orphan_try()) added early
orphaning of skbs.
This unfortunately added a performance regression in skb_tx_hash() in
case of stacked devices (bonding, vlans, ...)
Since skb->sk is now NULL, we cannot access sk->sk_hash anymore to
spread tx packets to multiple NIC queues on multiqueue devices.
skb_tx_hash() in this case only uses skb->protocol, same value for all
flows.
skb_orphan_try() can copy sk->sk_hash into skb->rxhash and skb_tx_hash()
can use this saved sk_hash value to compute its internal hash value.
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
| -rw-r--r-- | net/core/dev.c | 13 |
1 files changed, 10 insertions, 3 deletions
diff --git a/net/core/dev.c b/net/core/dev.c index 723a34710ad4..4b05fdf762ab 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -1911,8 +1911,16 @@ static int dev_gso_segment(struct sk_buff *skb) */ static inline void skb_orphan_try(struct sk_buff *skb) { - if (!skb_tx(skb)->flags) + struct sock *sk = skb->sk; + + if (sk && !skb_tx(skb)->flags) { + /* skb_tx_hash() wont be able to get sk. + * We copy sk_hash into skb->rxhash + */ + if (!skb->rxhash) + skb->rxhash = sk->sk_hash; skb_orphan(skb); + } } int dev_hard_start_xmit(struct sk_buff *skb, struct net_device *dev, @@ -1998,8 +2006,7 @@ u16 skb_tx_hash(const struct net_device *dev, const struct sk_buff *skb) if (skb->sk && skb->sk->sk_hash) hash = skb->sk->sk_hash; else - hash = (__force u16) skb->protocol; - + hash = (__force u16) skb->protocol ^ skb->rxhash; hash = jhash_1word(hash, hashrnd); return (u16) (((u64) hash * dev->real_num_tx_queues) >> 32); |