Commit fa4cb9eb authored by Pengcheng Yang's avatar Pengcheng Yang Committed by David S. Miller
Browse files

tcp: fix stretch ACK bugs in Yeah 



Change Yeah to properly handle stretch ACKs in additive
increase mode by passing in the count of ACKed packets
to tcp_cong_avoid_ai().

In addition, we re-implemented the scalable path using
tcp_cong_avoid_ai() and removed the pkts_acked variable.

Signed-off-by: default avatarPengcheng Yang <yangpc@wangsu.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent ca04f5d4

net/ipv4/tcp_yeah.c

+11 −30
Original line number Diff line number Diff line
@@ -36,8 +36,6 @@ struct yeah { 


	u32 reno_count;

	u32 fast_count;



	u32 pkts_acked;

};



static void tcp_yeah_init(struct sock *sk)
@@ -57,18 +55,6 @@ static void tcp_yeah_init(struct sock *sk) 
	tp->snd_cwnd_clamp = min_t(u32, tp->snd_cwnd_clamp, 0xffffffff/128);

}



static void tcp_yeah_pkts_acked(struct sock *sk,

				const struct ack_sample *sample)

{

	const struct inet_connection_sock *icsk = inet_csk(sk);

	struct yeah *yeah = inet_csk_ca(sk);



	if (icsk->icsk_ca_state == TCP_CA_Open)

		yeah->pkts_acked = sample->pkts_acked;



	tcp_vegas_pkts_acked(sk, sample);

}



static void tcp_yeah_cong_avoid(struct sock *sk, u32 ack, u32 acked)

{

	struct tcp_sock *tp = tcp_sk(sk);
@@ -77,24 +63,19 @@ static void tcp_yeah_cong_avoid(struct sock *sk, u32 ack, u32 acked) 
	if (!tcp_is_cwnd_limited(sk))

		return;



	if (tcp_in_slow_start(tp))

		tcp_slow_start(tp, acked);



	else if (!yeah->doing_reno_now) {

		/* Scalable */



		tp->snd_cwnd_cnt += yeah->pkts_acked;

		if (tp->snd_cwnd_cnt > min(tp->snd_cwnd, TCP_SCALABLE_AI_CNT)) {

			if (tp->snd_cwnd < tp->snd_cwnd_clamp)

				tp->snd_cwnd++;

			tp->snd_cwnd_cnt = 0;

	if (tcp_in_slow_start(tp)) {

		acked = tcp_slow_start(tp, acked);

		if (!acked)

			goto do_vegas;

	}



		yeah->pkts_acked = 1;



	if (!yeah->doing_reno_now) {

		/* Scalable */

		tcp_cong_avoid_ai(tp, min(tp->snd_cwnd, TCP_SCALABLE_AI_CNT),

				  acked);

	} else {

		/* Reno */

		tcp_cong_avoid_ai(tp, tp->snd_cwnd, 1);

		tcp_cong_avoid_ai(tp, tp->snd_cwnd, acked);

	}



	/* The key players are v_vegas.beg_snd_una and v_beg_snd_nxt.
@@ -118,7 +99,7 @@ static void tcp_yeah_cong_avoid(struct sock *sk, u32 ack, u32 acked) 
	 * of bytes we send in an RTT is often less than our cwnd will allow.

	 * So we keep track of our cwnd separately, in v_beg_snd_cwnd.

	 */



do_vegas:

	if (after(ack, yeah->vegas.beg_snd_nxt)) {

		/* We do the Vegas calculations only if we got enough RTT

		 * samples that we can be reasonably sure that we got
@@ -232,7 +213,7 @@ static struct tcp_congestion_ops tcp_yeah __read_mostly = { 
	.set_state	= tcp_vegas_state,

	.cwnd_event	= tcp_vegas_cwnd_event,

	.get_info	= tcp_vegas_get_info,

	.pkts_acked	= tcp_yeah_pkts_acked,

	.pkts_acked	= tcp_vegas_pkts_acked,



	.owner		= THIS_MODULE,

	.name		= "yeah",

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