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net: sk_add_backlog() take rmem_alloc into account

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Current socket backlog limit is not enough to really stop DDOS attacks,
because user thread spend many time to process a full backlog each
round, and user might crazy spin on socket lock.

We should add backlog size and receive_queue size (aka rmem_alloc) to
pace writers, and let user run without being slow down too much.

Introduce a sk_rcvqueues_full() helper, to avoid taking socket lock in
stress situations.

Under huge stress from a multiqueue/RPS enabled NIC, a single flow udp
receiver can now process ~200.000 pps (instead of ~100 pps before the
patch) on a 8 core machine.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet
2010-04-27 15:13:20 -07:00
committed by David S. Miller
parent 6e7676c1a7
commit c377411f24
5 changed files with 27 additions and 6 deletions
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8
net/ipv6/udp.c
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@@ -584,6 +584,10 @@ static void flush_stack(struct sock **stack, unsigned int count,
sk = stack[i];
if (skb1) {
if (sk_rcvqueues_full(sk, skb)) {
kfree_skb(skb1);
goto drop;
}
bh_lock_sock(sk);
if (!sock_owned_by_user(sk))
udpv6_queue_rcv_skb(sk, skb1);
@@ -759,6 +763,10 @@ int __udp6_lib_rcv(struct sk_buff *skb, struct udp_table *udptable,
/* deliver */
if (sk_rcvqueues_full(sk, skb)) {
sock_put(sk);
goto discard;
}
bh_lock_sock(sk);
if (!sock_owned_by_user(sk))
udpv6_queue_rcv_skb(sk, skb);