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tcp: back retransmit_high when it over-estimated

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If lost skb is sacked, we might have nothing to retransmit
as high as the retransmit_high is pointing to, so place
it lower to avoid unnecessary walking.

This is mainly for the case where high L'ed skbs gets sacked.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Ilpo Järvinen 2008-09-20 21:26:22 -07:00 committed by David S. Miller
parent 90638a04ad
commit 618d9f2554
1 changed files with 10 additions and 2 deletions
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12
net/ipv4/tcp_output.c
View file

@ -2035,16 +2035,22 @@ void tcp_xmit_retransmit_queue(struct sock *sk)
struct tcp_sock *tp = tcp_sk(sk); struct tcp_sock *tp = tcp_sk(sk);
struct sk_buff *skb; struct sk_buff *skb;
struct sk_buff *hole = NULL; struct sk_buff *hole = NULL;
u32 last_lost;
int mib_idx; int mib_idx;
int fwd_rexmitting = 0; int fwd_rexmitting = 0;
if (!tp->lost_out) if (!tp->lost_out)
tp->retransmit_high = tp->snd_una; tp->retransmit_high = tp->snd_una;
if (tp->retransmit_skb_hint) if (tp->retransmit_skb_hint) {
skb = tp->retransmit_skb_hint; skb = tp->retransmit_skb_hint;
else last_lost = TCP_SKB_CB(skb)->end_seq;
if (after(last_lost, tp->retransmit_high))
last_lost = tp->retransmit_high;
} else {
skb = tcp_write_queue_head(sk); skb = tcp_write_queue_head(sk);
last_lost = tp->snd_una;
}
/* First pass: retransmit lost packets. */ /* First pass: retransmit lost packets. */
tcp_for_write_queue_from(skb, sk) { tcp_for_write_queue_from(skb, sk) {
@ -2073,6 +2079,7 @@ void tcp_xmit_retransmit_queue(struct sock *sk)
mib_idx = LINUX_MIB_TCPFORWARDRETRANS; mib_idx = LINUX_MIB_TCPFORWARDRETRANS;
} else if (!before(TCP_SKB_CB(skb)->seq, tp->retransmit_high)) { } else if (!before(TCP_SKB_CB(skb)->seq, tp->retransmit_high)) {
tp->retransmit_high = last_lost;
if (!tcp_can_forward_retransmit(sk)) if (!tcp_can_forward_retransmit(sk))
break; break;
/* Backtrack if necessary to non-L'ed skb */ /* Backtrack if necessary to non-L'ed skb */
@ -2089,6 +2096,7 @@ void tcp_xmit_retransmit_queue(struct sock *sk)
continue; continue;
} else { } else {
last_lost = TCP_SKB_CB(skb)->end_seq;
if (icsk->icsk_ca_state != TCP_CA_Loss) if (icsk->icsk_ca_state != TCP_CA_Loss)
mib_idx = LINUX_MIB_TCPFASTRETRANS; mib_idx = LINUX_MIB_TCPFASTRETRANS;
else else