| Message ID | 1279034660.2634.439.camel@edumazet-laptop |
|---|---|
| State | Accepted, archived |
| Delegated to: | David Miller |
| Headers | show |
From: Eric Dumazet <eric.dumazet@gmail.com> Date: Tue, 13 Jul 2010 17:24:20 +0200 > 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> Applied, thanks Eric. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/net/core/dev.c b/net/core/dev.c index 723a347..70a900a 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);
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> --- net/core/dev.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-) -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html