[PATCH 1/3] Advance fast path pointer for first block only

[Baruch Even <baruch@ev-en.org>]

Only advance the SACK fast-path pointer for the first block, the fast-path
assumes that only the first block advances next time so we should not move the
skb for the next sack blocks.

Signed-Off-By: Baruch Even <baruch@ev-en.org>

---

I'm not sure about the fack_count part, this patch changes the value that is
maintained in this case.

Index: 2.6-rc6/net/ipv4/tcp_input.c
===================================================================
--- 2.6-rc6.orig/net/ipv4/tcp_input.c	2007-01-27 14:53:27.000000000 +0200
+++ 2.6-rc6/net/ipv4/tcp_input.c	2007-01-27 15:59:22.000000000 +0200
@@ -1048,8 +1048,13 @@
 			int in_sack, pcount;
 			u8 sacked;
 
-			tp->fastpath_skb_hint = skb;
-			tp->fastpath_cnt_hint = fack_count;
+			if (i == 0) {
+				/* Only advance the hint for the first SACK
+				 * block, the hint is for quickly handling the
+				 * advancing of the first SACK blocks only. */
+				tp->fastpath_skb_hint = skb;
+				tp->fastpath_cnt_hint = fack_count;
+			}
 
 			/* The retransmission queue is always in order, so
 			 * we can short-circuit the walk early.