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Commit 071d5080 authored by Yuchung Cheng's avatar Yuchung Cheng Committed by David S. Miller
Browse files

tcp: add tcp_in_slow_start helper 



Add a helper to test the slow start condition in various congestion
control modules and other places. This is to prepare a slight improvement
in policy as to exactly when to slow start.

Signed-off-by: default avatarYuchung Cheng <ycheng@google.com>
Signed-off-by: default avatarNeal Cardwell <ncardwell@google.com>
Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarNandita Dukkipati <nanditad@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 1007f59d

include/net/tcp.h

+6 −1
Original line number Diff line number Diff line
@@ -989,6 +989,11 @@ static inline unsigned int tcp_packets_in_flight(const struct tcp_sock *tp) 


#define TCP_INFINITE_SSTHRESH	0x7fffffff



static inline bool tcp_in_slow_start(const struct tcp_sock *tp)

{

	return tp->snd_cwnd <= tp->snd_ssthresh;

}



static inline bool tcp_in_initial_slowstart(const struct tcp_sock *tp)

{

	return tp->snd_ssthresh >= TCP_INFINITE_SSTHRESH;
@@ -1065,7 +1070,7 @@ static inline bool tcp_is_cwnd_limited(const struct sock *sk) 
	const struct tcp_sock *tp = tcp_sk(sk);



	/* If in slow start, ensure cwnd grows to twice what was ACKed. */

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

	if (tcp_in_slow_start(tp))

		return tp->snd_cwnd < 2 * tp->max_packets_out;



	return tp->is_cwnd_limited;

net/ipv4/tcp_bic.c

+1 −1
Original line number Diff line number Diff line
@@ -146,7 +146,7 @@ static void bictcp_cong_avoid(struct sock *sk, u32 ack, u32 acked) 
	if (!tcp_is_cwnd_limited(sk))

		return;



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

	if (tcp_in_slow_start(tp))

		tcp_slow_start(tp, acked);

	else {

		bictcp_update(ca, tp->snd_cwnd);

net/ipv4/tcp_cong.c

+1 −1
Original line number Diff line number Diff line
@@ -413,7 +413,7 @@ void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 acked) 
		return;



	/* In "safe" area, increase. */

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

	if (tcp_in_slow_start(tp)) {

		acked = tcp_slow_start(tp, acked);

		if (!acked)

			return;

net/ipv4/tcp_cubic.c

+2 −2
Original line number Diff line number Diff line
@@ -320,7 +320,7 @@ static void bictcp_cong_avoid(struct sock *sk, u32 ack, u32 acked) 
	if (!tcp_is_cwnd_limited(sk))

		return;



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

	if (tcp_in_slow_start(tp)) {

		if (hystart && after(ack, ca->end_seq))

			bictcp_hystart_reset(sk);

		acked = tcp_slow_start(tp, acked);
@@ -439,7 +439,7 @@ static void bictcp_acked(struct sock *sk, u32 cnt, s32 rtt_us) 
		ca->delay_min = delay;



	/* hystart triggers when cwnd is larger than some threshold */

	if (hystart && tp->snd_cwnd <= tp->snd_ssthresh &&

	if (hystart && tcp_in_slow_start(tp) &&

	    tp->snd_cwnd >= hystart_low_window)

		hystart_update(sk, delay);

}

net/ipv4/tcp_highspeed.c

+1 −1
Original line number Diff line number Diff line
@@ -116,7 +116,7 @@ static void hstcp_cong_avoid(struct sock *sk, u32 ack, u32 acked) 
	if (!tcp_is_cwnd_limited(sk))

		return;



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

	if (tcp_in_slow_start(tp))

		tcp_slow_start(tp, acked);

	else {

		/* Update AIMD parameters.