Commit 702821f4 authored Aug 28, 2013 by Eric Dumazet Committed by David S. Miller Aug 30, 2013

net: revert 8728c544 ("net: dev_pick_tx() fix")



commit 8728c544 ("net: dev_pick_tx() fix") and commit
b6fe83e9 ("bonding: refine IFF_XMIT_DST_RELEASE capability")
are quite incompatible : Queue selection is disabled because skb
dst was dropped before entering bonding device.

This causes major performance regression, mainly because TCP packets
for a given flow can be sent to multiple queues.

This is particularly visible when using the new FQ packet scheduler
with MQ + FQ setup on the slaves.

We can safely revert the first commit now that 416186fb
("net: Split core bits of netdev_pick_tx into __netdev_pick_tx")
properly caps the queue_index.

Reported-by: Xi Wang <xii@google.com>
Diagnosed-by: Xi Wang <xii@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Tom Herbert <therbert@google.com>
Cc: Alexander Duyck <alexander.h.duyck@intel.com>
Cc: Denys Fedorysychenko <nuclearcat@nuclearcat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent 25ad6117

net/core/flow_dissector.c

+3 −8

Original line number	Diff line number	Diff line
		@@ -346,15 +346,10 @@ u16 __netdev_pick_tx(struct net_device dev, struct sk_buff skb)
		if (new_index < 0)
		new_index = skb_tx_hash(dev, skb);

		if (queue_index != new_index && sk) {
		struct dst_entry *dst =
		rcu_dereference_check(sk->sk_dst_cache, 1);

		if (dst && skb_dst(skb) == dst)
		if (queue_index != new_index && sk &&
		rcu_access_pointer(sk->sk_dst_cache))
		sk_tx_queue_set(sk, queue_index);

		}

		queue_index = new_index;
		}