Re: Timeline of IPoIB performance

[Roland Dreier <rolandd@cisco.com>]

    Herbert> Try reverting the changeset

    Herbert> 314324121f9b94b2ca657a494cf2b9cb0e4a28cc

    Herbert> which lies between these two points and may be relevant.

Matt, I pulled this out of git for you.  I guess Herbert is suggesting
to patch -R the below against 2.6.12-rc5:

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 79835a6..5bad504 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -4355,16 +4355,7 @@ int tcp_rcv_established(struct sock *sk,
 					goto no_ack;
 			}
 
-			if (eaten) {
-				if (tcp_in_quickack_mode(tp)) {
-					tcp_send_ack(sk);
-				} else {
-					tcp_send_delayed_ack(sk);
-				}
-			} else {
-				__tcp_ack_snd_check(sk, 0);
-			}
-
+			__tcp_ack_snd_check(sk, 0);
 no_ack:
 			if (eaten)
 				__kfree_skb(skb);