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[TCP]: Limit processing lost_retrans loop to work-to-do cases

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This addition of lost_retrans_low to tcp_sock might be
unnecessary, it's not clear how often lost_retrans worker is
executed when there wasn't work to do.

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 2007-10-11 17:36:13 -07:00 committed by David S. Miller
parent f785a8e28b
commit b08d6cb22c
3 changed files with 15 additions and 3 deletions
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2
include/linux/tcp.h
View File

@ -348,6 +348,8 @@ struct tcp_sock {
int lost_cnt_hint;
int retransmit_cnt_hint;
u32 lost_retrans_low; /* Sent seq after any rxmit (lowest) */
u16 advmss; /* Advertised MSS */
u16 prior_ssthresh; /* ssthresh saved at recovery start */
u32 lost_out; /* Lost packets */

14
net/ipv4/tcp_input.c
View File

@ -1112,7 +1112,8 @@ static int tcp_is_sackblock_valid(struct tcp_sock *tp, int is_dsack,
*
* Search retransmitted skbs from write_queue that were sent when snd_nxt was
* less than what is now known to be received by the other end (derived from
* SACK blocks by the caller).
* SACK blocks by the caller). Also calculate the lowest snd_nxt among the
* remaining retransmitted skbs to avoid some costly processing per ACKs.
*/
static int tcp_mark_lost_retrans(struct sock *sk, u32 received_upto)
{
@ -1120,6 +1121,7 @@ static int tcp_mark_lost_retrans(struct sock *sk, u32 received_upto)
struct sk_buff *skb;
int flag = 0;
int cnt = 0;
u32 new_low_seq = 0;
tcp_for_write_queue(skb, sk) {
u32 ack_seq = TCP_SKB_CB(skb)->ack_seq;
@ -1151,9 +1153,15 @@ static int tcp_mark_lost_retrans(struct sock *sk, u32 received_upto)
NET_INC_STATS_BH(LINUX_MIB_TCPLOSTRETRANSMIT);
}
} else {
if (!new_low_seq || before(ack_seq, new_low_seq))
new_low_seq = ack_seq;
cnt += tcp_skb_pcount(skb);
}
}
if (tp->retrans_out)
tp->lost_retrans_low = new_low_seq;
return flag;
}
@ -1481,8 +1489,8 @@ tcp_sacktag_write_queue(struct sock *sk, struct sk_buff *ack_skb, u32 prior_snd_
}
}
if (tp->retrans_out && highest_sack_end_seq &&
after(highest_sack_end_seq, tp->high_seq) &&
if (tp->retrans_out &&
after(highest_sack_end_seq, tp->lost_retrans_low) &&
icsk->icsk_ca_state == TCP_CA_Recovery)
flag |= tcp_mark_lost_retrans(sk, highest_sack_end_seq);

2
net/ipv4/tcp_output.c
View File

@ -1914,6 +1914,8 @@ int tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb)
printk(KERN_DEBUG "retrans_out leaked.\n");
}
#endif
if (!tp->retrans_out)
tp->lost_retrans_low = tp->snd_nxt;
TCP_SKB_CB(skb)->sacked |= TCPCB_RETRANS;
tp->retrans_out += tcp_skb_pcount(skb);