Bug #366

Description

———- Forwarded message ———-
From: Eric Dumazet eric.dumazet@gmail.com
Date: Tue, Apr 17, 2012 at 2:28 AM
Subject: [PATCH] tcp: fix tcp_grow_window() for large incoming frames
To: David Miller davem@davemloft.net
Cc: Neal Cardwell ncardwell@google.com, Tom Herbert
therbert@google.com, netdev netdev@vger.kernel.org

From: Eric Dumazet edumazet@google.com

tcp_grow_window() has to grow rcv_ssthresh up to window_clamp, allowing
sender to increase its window.

tcp_grow_window() still assumes a tcp frame is under MSS, but its no
longer true with LRO/GRO.

This patch fixes one of the performance issue we noticed with GRO on.

Signed-off-by: Eric Dumazet edumazet@google.com
Cc: Neal Cardwell ncardwell@google.com
Cc: Tom Herbert therbert@google.com
—
Sorry for the delay, this was discussed a long time ago.

 net/ipv4/tcp_input.c |    1 +
 1 file changed, 1 insertion(+)

diff –git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 9944c1d..3ff36406 100644
— a/net/ipv4/tcp_input.c
**+ b/net/ipv4/tcp_input.c
@ -335,6 +335,7@ static void tcp_grow_window(struct sock *sk, const
struct sk_buff *skb)
                       incr = __tcp_grow_window(sk, skb);

               if (incr) {
+                       incr = max_t(int, incr, 2 * skb->len);
                       tp->rcv_ssthresh = min(tp->rcv_ssthresh + incr,
                                              tp->window_clamp);
                       inet_csk(sk)->icsk_ack.quick |= 1;