From 2594a2a928a010bf27e6545f90bc2de7ed5ed075 Mon Sep 17 00:00:00 2001
From: Eric Dumazet <edumazet@google.com>
Date: Fri, 9 Sep 2016 14:22:45 -0700
Subject: [PATCH] tcp: better use ooo_last_skb in tcp_data_queue_ofo()
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Willem noticed that we could avoid an rbtree lookup if the
the attempt to coalesce incoming skb to the last skb failed
for some reason.
Since most ooo additions are at the tail, this is definitely
worth adding a test and fast path.
Suggested-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Yaogong Wang <wygivan@google.com>
Cc: Yuchung Cheng <ycheng@google.com>
Cc: Neal Cardwell <ncardwell@google.com>
Cc: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
net/ipv4/tcp_input.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index a5934c4c8cd4e..70b892db99018 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -4461,6 +4461,12 @@ static void tcp_data_queue_ofo(struct sock *sk, struct sk_buff *skb)
skb = NULL;
goto add_sack;
}
+ /* Can avoid an rbtree lookup if we are adding skb after ooo_last_skb */
+ if (!before(seq, TCP_SKB_CB(tp->ooo_last_skb)->end_seq)) {
+ parent = &tp->ooo_last_skb->rbnode;
+ p = &parent->rb_right;
+ goto insert;
+ }
/* Find place to insert this segment. Handle overlaps on the way. */
parent = NULL;
@@ -4503,7 +4509,7 @@ static void tcp_data_queue_ofo(struct sock *sk, struct sk_buff *skb)
}
p = &parent->rb_right;
}
-
+insert:
/* Insert segment into RB tree. */
rb_link_node(&skb->rbnode, parent, p);
rb_insert_color(&skb->rbnode, &tp->out_of_order_queue);
--
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