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Commit 758ce5c8 authored by Ilpo Järvinen's avatar Ilpo Järvinen Committed by David S. Miller
Browse files

tcp: add helper for AI algorithm 



It seems that implementation in yeah was inconsistent to what
other did as it would increase cwnd one ack earlier than the
others do.

Size benefits:

  bictcp_cong_avoid |  -36
  tcp_cong_avoid_ai |  +52
  bictcp_cong_avoid |  -34
  tcp_scalable_cong_avoid |  -36
  tcp_veno_cong_avoid |  -12
  tcp_yeah_cong_avoid |  -38

= -104 bytes total

Signed-off-by: default avatarIlpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 571a5dd8

include/net/tcp.h

+1 −0
Original line number Diff line number Diff line
@@ -685,6 +685,7 @@ extern void tcp_get_allowed_congestion_control(char *buf, size_t len); 
extern int tcp_set_allowed_congestion_control(char *allowed);

extern int tcp_set_congestion_control(struct sock *sk, const char *name);

extern void tcp_slow_start(struct tcp_sock *tp);

extern void tcp_cong_avoid_ai(struct tcp_sock *tp, u32 w);



extern struct tcp_congestion_ops tcp_init_congestion_ops;

extern u32 tcp_reno_ssthresh(struct sock *sk);

net/ipv4/tcp_bic.c

+1 −10
Original line number Diff line number Diff line
@@ -149,16 +149,7 @@ static void bictcp_cong_avoid(struct sock *sk, u32 ack, u32 in_flight) 
		tcp_slow_start(tp);

	else {

		bictcp_update(ca, tp->snd_cwnd);



		/* In dangerous area, increase slowly.

		 * In theory this is tp->snd_cwnd += 1 / tp->snd_cwnd

		 */

		if (tp->snd_cwnd_cnt >= ca->cnt) {

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

				tp->snd_cwnd++;

			tp->snd_cwnd_cnt = 0;

		} else

			tp->snd_cwnd_cnt++;

		tcp_cong_avoid_ai(tp, ca->cnt);

	}



}

net/ipv4/tcp_cong.c

+14 −7
Original line number Diff line number Diff line
@@ -336,6 +336,19 @@ void tcp_slow_start(struct tcp_sock *tp) 
}

EXPORT_SYMBOL_GPL(tcp_slow_start);



/* In theory this is tp->snd_cwnd += 1 / tp->snd_cwnd (or alternative w) */

void tcp_cong_avoid_ai(struct tcp_sock *tp, u32 w)

{

	if (tp->snd_cwnd_cnt >= w) {

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

			tp->snd_cwnd++;

		tp->snd_cwnd_cnt = 0;

	} else {

		tp->snd_cwnd_cnt++;

	}

}

EXPORT_SYMBOL_GPL(tcp_cong_avoid_ai);



/*

 * TCP Reno congestion control

 * This is special case used for fallback as well.
@@ -365,13 +378,7 @@ void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 in_flight) 
				tp->snd_cwnd++;

		}

	} else {

		/* In theory this is tp->snd_cwnd += 1 / tp->snd_cwnd */

		if (tp->snd_cwnd_cnt >= tp->snd_cwnd) {

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

				tp->snd_cwnd++;

			tp->snd_cwnd_cnt = 0;

		} else

			tp->snd_cwnd_cnt++;

		tcp_cong_avoid_ai(tp, tp->snd_cwnd);

	}

}

EXPORT_SYMBOL_GPL(tcp_reno_cong_avoid);

net/ipv4/tcp_cubic.c

+1 −10
Original line number Diff line number Diff line
@@ -294,16 +294,7 @@ static void bictcp_cong_avoid(struct sock *sk, u32 ack, u32 in_flight) 
		tcp_slow_start(tp);

	} else {

		bictcp_update(ca, tp->snd_cwnd);



		/* In dangerous area, increase slowly.

		 * In theory this is tp->snd_cwnd += 1 / tp->snd_cwnd

		 */

		if (tp->snd_cwnd_cnt >= ca->cnt) {

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

				tp->snd_cwnd++;

			tp->snd_cwnd_cnt = 0;

		} else

			tp->snd_cwnd_cnt++;

		tcp_cong_avoid_ai(tp, ca->cnt);

	}



}

net/ipv4/tcp_scalable.c

+2 −8
Original line number Diff line number Diff line
@@ -24,14 +24,8 @@ static void tcp_scalable_cong_avoid(struct sock *sk, u32 ack, u32 in_flight) 


	if (tp->snd_cwnd <= tp->snd_ssthresh)

		tcp_slow_start(tp);

	else {

		tp->snd_cwnd_cnt++;

		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;

		}

	}

	else

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

}



static u32 tcp_scalable_ssthresh(struct sock *sk)