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Commit b08d6cb2 authored by Ilpo Järvinen's avatar Ilpo Järvinen Committed by David S. Miller
Browse files

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



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: default avatarIlpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent f785a8e2

include/linux/tcp.h

+2 −0
Original line number Diff line number Diff line
@@ -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			*/

net/ipv4/tcp_input.c

+11 −3
Original line number Diff line number Diff line
@@ -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);

net/ipv4/tcp_output.c

+2 −0
Original line number Diff line number Diff line
@@ -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);