generic: net: tcp: backport tcp tx performance patches

[openwrt/staging/hauke.git] / target / linux / generic / backport-4.9 / 024-6-tcp-tcp_mtu_probe-is-likely-to-exit-early.patch

diff --git a/target/linux/generic/backport-4.9/024-6-tcp-tcp_mtu_probe-is-likely-to-exit-early.patch b/target/linux/generic/backport-4.9/024-6-tcp-tcp_mtu_probe-is-likely-to-exit-early.patch
new file mode 100644 (file)
index 0000000..f0ae2a9
--- /dev/null
+++ b/target/linux/generic/backport-4.9/024-6-tcp-tcp_mtu_probe-is-likely-to-exit-early.patch
@@ -0,0 +1,55 @@
+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
+@@ -1925,26 +1925,26 @@ static inline void tcp_mtu_check_reprobe
+  */
+ 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,