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Commit 8ea333eb authored by John Heffner's avatar John Heffner Committed by David S. Miller
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[TCP]: Fix and simplify microsecond rtt sampling 



This changes the microsecond RTT sampling so that samples are taken in
the same way that RTT samples are taken for the RTO calculator: on the
last segment acknowledged, and only when the segment hasn't been
retransmitted.

Signed-off-by: default avatarJohn Heffner <jheffner@psc.edu>
Acked-by: default avatarStephen Hemminger <shemminger@osdl.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent bfbea8a8

net/ipv4/tcp_input.c

+8 −8
Original line number Diff line number Diff line
@@ -2239,13 +2239,12 @@ static int tcp_tso_acked(struct sock *sk, struct sk_buff *skb, 
	return acked;

}



static u32 tcp_usrtt(const struct sk_buff *skb)

static u32 tcp_usrtt(struct timeval *tv)

{

	struct timeval tv, now;

	struct timeval now;



	do_gettimeofday(&now);

	skb_get_timestamp(skb, &tv);

	return (now.tv_sec - tv.tv_sec) * 1000000 + (now.tv_usec - tv.tv_usec);

	return (now.tv_sec - tv->tv_sec) * 1000000 + (now.tv_usec - tv->tv_usec);

}



/* Remove acknowledged frames from the retransmission queue. */
@@ -2260,6 +2259,7 @@ static int tcp_clean_rtx_queue(struct sock *sk, __s32 *seq_rtt_p) 
	u32 pkts_acked = 0;

	void (*rtt_sample)(struct sock *sk, u32 usrtt)

		= icsk->icsk_ca_ops->rtt_sample;

	struct timeval tv;



	while ((skb = skb_peek(&sk->sk_write_queue)) &&

	       skb != sk->sk_send_head) {
@@ -2308,8 +2308,7 @@ static int tcp_clean_rtx_queue(struct sock *sk, __s32 *seq_rtt_p) 
				seq_rtt = -1;

			} else if (seq_rtt < 0) {

				seq_rtt = now - scb->when;

				if (rtt_sample)

					(*rtt_sample)(sk, tcp_usrtt(skb));

				skb_get_timestamp(skb, &tv);

			}

			if (sacked & TCPCB_SACKED_ACKED)

				tp->sacked_out -= tcp_skb_pcount(skb);
@@ -2322,8 +2321,7 @@ static int tcp_clean_rtx_queue(struct sock *sk, __s32 *seq_rtt_p) 
			}

		} else if (seq_rtt < 0) {

			seq_rtt = now - scb->when;

			if (rtt_sample)

				(*rtt_sample)(sk, tcp_usrtt(skb));

			skb_get_timestamp(skb, &tv);

		}

		tcp_dec_pcount_approx(&tp->fackets_out, skb);

		tcp_packets_out_dec(tp, skb);
@@ -2335,6 +2333,8 @@ static int tcp_clean_rtx_queue(struct sock *sk, __s32 *seq_rtt_p) 
	if (acked&FLAG_ACKED) {

		tcp_ack_update_rtt(sk, acked, seq_rtt);

		tcp_ack_packets_out(sk, tp);

		if (rtt_sample && !(acked & FLAG_RETRANS_DATA_ACKED))

			(*rtt_sample)(sk, tcp_usrtt(&tv));



		if (icsk->icsk_ca_ops->pkts_acked)

			icsk->icsk_ca_ops->pkts_acked(sk, pkts_acked);