From: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Date: Sat, 28 Feb 2009 04:44:27 +0000 (+0000)
Subject: tcp: don't backtrack to sacked skbs
X-Git-Url: http://git.cdn.openwrt.org/?a=commitdiff_plain;h=ac11ba753f3aa839292c1a3b6c971c637ad2e839;p=openwrt%2Fstaging%2Fblogic.git

tcp: don't backtrack to sacked skbs

Backtracking to sacked skbs is a horrible performance killer
since the hint cannot be advanced successfully past them...
...And it's totally unnecessary too.

In theory this is 2.6.27..28 regression but I doubt anybody
can make .28 to have worse performance because of other TCP
improvements.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>
---

diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index f6f61b3e677b..2471cd4f66db 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -2065,7 +2065,7 @@ begin_fwd:
 			goto begin_fwd;
 
 		} else if (!(sacked & TCPCB_LOST)) {
-			if (hole == NULL && !(sacked & TCPCB_SACKED_RETRANS))
+			if (hole == NULL && !(sacked & (TCPCB_SACKED_RETRANS|TCPCB_SACKED_ACKED)))
 				hole = skb;
 			continue;