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From 12a59abc22d6664f7d3944f625ceefee92de8820 Mon Sep 17 00:00:00 2001
From: Eric Dumazet <edumazet@google.com>
Date: Sat, 3 Dec 2016 11:14:55 -0800
Subject: [PATCH 06/10] tcp: tcp_mtu_probe() is likely to exit early
Adding a likely() in tcp_mtu_probe() moves its code which used to
be inlined in front of tcp_write_xmit()
We still have a cache line miss to access icsk->icsk_mtup.enabled,
we will probably have to reorganize fields to help data locality.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
net/ipv4/tcp_output.c | 18 +++++++++---------
1 file changed, 9 insertions(+), 9 deletions(-)
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -1973,26 +1973,26 @@ static bool tcp_can_coalesce_send_queue_
*/
static int tcp_mtu_probe(struct sock *sk)
{
- struct tcp_sock *tp = tcp_sk(sk);
struct inet_connection_sock *icsk = inet_csk(sk);
+ struct tcp_sock *tp = tcp_sk(sk);
struct sk_buff *skb, *nskb, *next;
struct net *net = sock_net(sk);
- int len;
int probe_size;
int size_needed;
- int copy;
+ int copy, len;
int mss_now;
int interval;
/* Not currently probing/verifying,
* not in recovery,
* have enough cwnd, and
- * not SACKing (the variable headers throw things off) */
- if (!icsk->icsk_mtup.enabled ||
- icsk->icsk_mtup.probe_size ||
- inet_csk(sk)->icsk_ca_state != TCP_CA_Open ||
- tp->snd_cwnd < 11 ||
- tp->rx_opt.num_sacks || tp->rx_opt.dsack)
+ * not SACKing (the variable headers throw things off)
+ */
+ if (likely(!icsk->icsk_mtup.enabled ||
+ icsk->icsk_mtup.probe_size ||
+ inet_csk(sk)->icsk_ca_state != TCP_CA_Open ||
+ tp->snd_cwnd < 11 ||
+ tp->rx_opt.num_sacks || tp->rx_opt.dsack))
return -1;
/* Use binary search for probe_size between tcp_mss_base,
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