tcp: remove false sharing in tcp_rcv_state_process()
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>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 7ea7034..90e0d925 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -5796,8 +5796,6 @@
int queued = 0;
bool acceptable;
- tp->rx_opt.saw_tstamp = 0;
-
switch (sk->sk_state) {
case TCP_CLOSE:
goto discard;
@@ -5838,6 +5836,7 @@
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 @@
return 0;
}
+ tp->rx_opt.saw_tstamp = 0;
req = tp->fastopen_rsk;
if (req) {
WARN_ON_ONCE(sk->sk_state != TCP_SYN_RECV &&
