From 12a59abc22d6664f7d3944f625ceefee92de8820 Mon Sep 17 00:00:00 2001 From: Eric Dumazet 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 Signed-off-by: David S. Miller --- 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 @@ -1976,26 +1976,26 @@ 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,