From ccdbb6e96beca362db876d820ac1e560ff6d9579 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Thu, 10 Oct 2013 08:43:00 -0700 Subject: [PATCH] tcp: tcp_transmit_skb() optimizations 1) We need to take a timestamp only for skb that should be cloned. Other skbs are not in write queue and no rtt estimation is done on them. 2) the unlikely() hint is wrong for receivers (they send pure ACK) Signed-off-by: Eric Dumazet Cc: MF Nowlan Cc: Yuchung Cheng Cc: Neal Cardwell Acked-By: Yuchung Cheng Signed-off-by: David S. Miller --- net/ipv4/tcp_output.c | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-) diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index 2822ad0..e5ce0e1 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -850,15 +850,15 @@ static int tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, int clone_it, BUG_ON(!skb || !tcp_skb_pcount(skb)); - /* If congestion control is doing timestamping, we must - * take such a timestamp before we potentially clone/copy. - */ - if (icsk->icsk_ca_ops->flags & TCP_CONG_RTT_STAMP) - __net_timestamp(skb); - - if (likely(clone_it)) { + if (clone_it) { const struct sk_buff *fclone = skb + 1; + /* If congestion control is doing timestamping, we must + * take such a timestamp before we potentially clone/copy. + */ + if (icsk->icsk_ca_ops->flags & TCP_CONG_RTT_STAMP) + __net_timestamp(skb); + if (unlikely(skb->fclone == SKB_FCLONE_ORIG && fclone->fclone == SKB_FCLONE_CLONE)) NET_INC_STATS_BH(sock_net(sk), -- 2.7.4