Commit fb4d3d1d authored by Yuchung Cheng's avatar Yuchung Cheng Committed by David S. Miller
Browse files

tcp: move tcp_update_cwnd_in_recovery 



To prepare replacing rate halving with PRR algorithm in CWR state.

Signed-off-by: default avatarYuchung Cheng <ycheng@google.com>
Acked-by: default avatarNeal Cardwell <ncardwell@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 09484d1f

net/ipv4/tcp_input.c

+32 −32
Original line number Diff line number Diff line
@@ -2700,6 +2700,38 @@ static bool tcp_try_undo_loss(struct sock *sk) 
	return false;

}



/* This function implements the PRR algorithm, specifcally the PRR-SSRB

 * (proportional rate reduction with slow start reduction bound) as described in

 * http://www.ietf.org/id/draft-mathis-tcpm-proportional-rate-reduction-01.txt.

 * It computes the number of packets to send (sndcnt) based on packets newly

 * delivered:

 *   1) If the packets in flight is larger than ssthresh, PRR spreads the

 *	cwnd reductions across a full RTT.

 *   2) If packets in flight is lower than ssthresh (such as due to excess

 *	losses and/or application stalls), do not perform any further cwnd

 *	reductions, but instead slow start up to ssthresh.

 */

static void tcp_update_cwnd_in_recovery(struct sock *sk, int newly_acked_sacked,

					int fast_rexmit, int flag)

{

	struct tcp_sock *tp = tcp_sk(sk);

	int sndcnt = 0;

	int delta = tp->snd_ssthresh - tcp_packets_in_flight(tp);



	if (tcp_packets_in_flight(tp) > tp->snd_ssthresh) {

		u64 dividend = (u64)tp->snd_ssthresh * tp->prr_delivered +

			       tp->prior_cwnd - 1;

		sndcnt = div_u64(dividend, tp->prior_cwnd) - tp->prr_out;

	} else {

		sndcnt = min_t(int, delta,

			       max_t(int, tp->prr_delivered - tp->prr_out,

				     newly_acked_sacked) + 1);

	}



	sndcnt = max(sndcnt, (fast_rexmit ? 1 : 0));

	tp->snd_cwnd = tcp_packets_in_flight(tp) + sndcnt;

}



static inline void tcp_complete_cwr(struct sock *sk)

{

	struct tcp_sock *tp = tcp_sk(sk);
@@ -2854,38 +2886,6 @@ void tcp_simple_retransmit(struct sock *sk) 
}

EXPORT_SYMBOL(tcp_simple_retransmit);



/* This function implements the PRR algorithm, specifcally the PRR-SSRB

 * (proportional rate reduction with slow start reduction bound) as described in

 * http://www.ietf.org/id/draft-mathis-tcpm-proportional-rate-reduction-01.txt.

 * It computes the number of packets to send (sndcnt) based on packets newly

 * delivered:

 *   1) If the packets in flight is larger than ssthresh, PRR spreads the

 *	cwnd reductions across a full RTT.

 *   2) If packets in flight is lower than ssthresh (such as due to excess

 *	losses and/or application stalls), do not perform any further cwnd

 *	reductions, but instead slow start up to ssthresh.

 */

static void tcp_update_cwnd_in_recovery(struct sock *sk, int newly_acked_sacked,

					int fast_rexmit, int flag)

{

	struct tcp_sock *tp = tcp_sk(sk);

	int sndcnt = 0;

	int delta = tp->snd_ssthresh - tcp_packets_in_flight(tp);



	if (tcp_packets_in_flight(tp) > tp->snd_ssthresh) {

		u64 dividend = (u64)tp->snd_ssthresh * tp->prr_delivered +

			       tp->prior_cwnd - 1;

		sndcnt = div_u64(dividend, tp->prior_cwnd) - tp->prr_out;

	} else {

		sndcnt = min_t(int, delta,

			       max_t(int, tp->prr_delivered - tp->prr_out,

				     newly_acked_sacked) + 1);

	}



	sndcnt = max(sndcnt, (fast_rexmit ? 1 : 0));

	tp->snd_cwnd = tcp_packets_in_flight(tp) + sndcnt;

}



static void tcp_enter_recovery(struct sock *sk, bool ece_ack)

{

	struct tcp_sock *tp = tcp_sk(sk);