diff mbox

[net-next,2/2] tcp: remove false sharing in tcp_rcv_state_process()

Message ID 1460610340-22163-3-git-send-email-edumazet@google.com
State Accepted, archived
Delegated to: David Miller
Headers show

Commit Message

Eric Dumazet April 14, 2016, 5:05 a.m. UTC 
Last known hot point during SYNFLOOD attack is the clearing
of rx_opt.saw_tstamp in tcp_rcv_state_process()

It is not needed for a listener, so we move it where it matters.

Performance while a SYNFLOOD hits a single listener socket
went from 5 Mpps to 6 Mpps on my test server (24 cores, 8 NIC RX queues)

Signed-off-by: Eric Dumazet <edumazet@google.com>
---
 net/ipv4/tcp_input.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
diff mbox

Patch

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 7ea7034af83f..90e0d9256b74 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -5796,8 +5796,6 @@  int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb)
 	int queued = 0;
 	bool acceptable;
 
-	tp->rx_opt.saw_tstamp = 0;
-
 	switch (sk->sk_state) {
 	case TCP_CLOSE:
 		goto discard;
@@ -5838,6 +5836,7 @@  int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb)
 		goto discard;
 
 	case TCP_SYN_SENT:
+		tp->rx_opt.saw_tstamp = 0;
 		queued = tcp_rcv_synsent_state_process(sk, skb, th);
 		if (queued >= 0)
 			return queued;
@@ -5849,6 +5848,7 @@  int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb)
 		return 0;
 	}
 
+	tp->rx_opt.saw_tstamp = 0;
 	req = tp->fastopen_rsk;
 	if (req) {
 		WARN_ON_ONCE(sk->sk_state != TCP_SYN_RECV &&