From 92ee76b6d99bfcdab6162816c9025541ef7248eb Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ilpo=20J=C3=A4rvinen?= <ilpo.jarvinen@helsinki.fi>
Date: Mon, 24 Nov 2008 21:26:56 -0800
Subject: [PATCH] tcp: Make shifting not clear the hints
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The earlier version was just very basic one which is "playing
safe" by always clearing the hints. However, clearing of a hint
is extremely costly operation with large windows, so it must be
avoided at all cost whenever possible, there is a way with
shifting too achieve not-clearing.
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
net/ipv4/tcp_input.c | 16 ++++++++++++++--
1 file changed, 14 insertions(+), 2 deletions(-)
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 97d57676b8ee..e6291dde3348 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -1379,6 +1379,11 @@ static int tcp_shifted_skb(struct sock *sk, struct sk_buff *prev,
BUG_ON(!pcount);
+ /* Tweak before seqno plays */
+ if (!tcp_is_fack(tp) && tcp_is_sack(tp) && tp->lost_skb_hint &&
+ !before(TCP_SKB_CB(tp->lost_skb_hint)->seq, TCP_SKB_CB(skb)->seq))
+ tp->lost_cnt_hint += pcount;
+
TCP_SKB_CB(prev)->end_seq += shifted;
TCP_SKB_CB(skb)->seq += shifted;
@@ -1408,8 +1413,6 @@ static int tcp_shifted_skb(struct sock *sk, struct sk_buff *prev,
/* Difference in this won't matter, both ACKed by the same cumul. ACK */
TCP_SKB_CB(prev)->sacked |= (TCP_SKB_CB(skb)->sacked & TCPCB_EVER_RETRANS);
- tcp_clear_all_retrans_hints(tp);
-
if (skb->len > 0) {
BUG_ON(!tcp_skb_pcount(skb));
return 0;
@@ -1417,6 +1420,15 @@ static int tcp_shifted_skb(struct sock *sk, struct sk_buff *prev,
/* Whole SKB was eaten :-) */
+ if (skb == tp->retransmit_skb_hint)
+ tp->retransmit_skb_hint = prev;
+ if (skb == tp->scoreboard_skb_hint)
+ tp->scoreboard_skb_hint = prev;
+ if (skb == tp->lost_skb_hint) {
+ tp->lost_skb_hint = prev;
+ tp->lost_cnt_hint -= tcp_skb_pcount(prev);
+ }
+
TCP_SKB_CB(skb)->flags |= TCP_SKB_CB(prev)->flags;
if (skb == tcp_highest_sack(sk))
tcp_advance_highest_sack(sk, skb);
--
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