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Message-Id: <20140514.140828.379626997254455792.davem@davemloft.net>
Date: Wed, 14 May 2014 14:08:28 -0400 (EDT)
From: David Miller <davem@...emloft.net>
To: panweiping3@...il.com
Cc: netdev@...r.kernel.org
Subject: Re: [PATCH net] tcp: set retransmit_high on loop exit
From: Weiping Pan <panweiping3@...il.com>
Date: Sun, 11 May 2014 20:57:30 +0800
> To save some CPU cycles slightly.
>
> Signed-off-by: Weiping Pan <panweiping3@...il.com>
Can a TCP expert please review this?
> ---
> net/ipv4/tcp_input.c | 8 ++++++--
> 1 file changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
> index d6b46eb..e431037 100644
> --- a/net/ipv4/tcp_input.c
> +++ b/net/ipv4/tcp_input.c
> @@ -1941,8 +1941,13 @@ void tcp_enter_loss(struct sock *sk, int how)
> tcp_clear_all_retrans_hints(tp);
>
> tcp_for_write_queue(skb, sk) {
> - if (skb == tcp_send_head(sk))
> + if (skb == tcp_send_head(sk)) {
> + if (skb != tcp_write_queue_head(sk)) {
> + skb = tcp_write_queue_prev(sk, skb);
> + tp->retransmit_high = TCP_SKB_CB(skb)->end_seq;
> + }
> break;
> + }
>
> if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_RETRANS)
> tp->undo_marker = 0;
> @@ -1952,7 +1957,6 @@ void tcp_enter_loss(struct sock *sk, int how)
> TCP_SKB_CB(skb)->sacked &= ~TCPCB_SACKED_ACKED;
> TCP_SKB_CB(skb)->sacked |= TCPCB_LOST;
> tp->lost_out += tcp_skb_pcount(skb);
> - tp->retransmit_high = TCP_SKB_CB(skb)->end_seq;
> }
> }
> tcp_verify_left_out(tp);
> --
> 1.9.0
>
> --
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