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Commit 72dc5b92 authored by Stephen Hemminger's avatar Stephen Hemminger Committed by David S. Miller
Browse files

[TCP]: Minimum congestion window consolidation. 



Many of the TCP congestion methods all just use ssthresh
as the minimum congestion window on decrease.  Rather than
duplicating the code, just have that be the default if that
handle in the ops structure is not set.

Minor behaviour change to TCP compound.  It probably wants
to use this (ssthresh) as lower bound, rather than ssthresh/2
because the latter causes undershoot on loss.

Signed-off-by: default avatarStephen Hemminger <shemminger@osdl.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent a4ed2584

include/net/tcp.h

+2 −2
Original line number Diff line number Diff line
@@ -632,7 +632,7 @@ struct tcp_congestion_ops { 
	/* return slow start threshold (required) */

	u32 (*ssthresh)(struct sock *sk);

	/* lower bound for congestion window (optional) */

	u32 (*min_cwnd)(struct sock *sk);

	u32 (*min_cwnd)(const struct sock *sk);

	/* do new cwnd calculation (required) */

	void (*cong_avoid)(struct sock *sk, u32 ack,

			   u32 rtt, u32 in_flight, int good_ack);
@@ -667,7 +667,7 @@ extern struct tcp_congestion_ops tcp_init_congestion_ops; 
extern u32 tcp_reno_ssthresh(struct sock *sk);

extern void tcp_reno_cong_avoid(struct sock *sk, u32 ack,

				u32 rtt, u32 in_flight, int flag);

extern u32 tcp_reno_min_cwnd(struct sock *sk);

extern u32 tcp_reno_min_cwnd(const struct sock *sk);

extern struct tcp_congestion_ops tcp_reno;



static inline void tcp_set_ca_state(struct sock *sk, const u8 ca_state)

net/ipv4/tcp_bic.c

+0 −7
Original line number Diff line number Diff line
@@ -198,12 +198,6 @@ static u32 bictcp_undo_cwnd(struct sock *sk) 
	return max(tp->snd_cwnd, ca->last_max_cwnd);

}



static u32 bictcp_min_cwnd(struct sock *sk)

{

	const struct tcp_sock *tp = tcp_sk(sk);

	return tp->snd_ssthresh;

}



static void bictcp_state(struct sock *sk, u8 new_state)

{

	if (new_state == TCP_CA_Loss)
@@ -231,7 +225,6 @@ static struct tcp_congestion_ops bictcp = { 
	.cong_avoid	= bictcp_cong_avoid,

	.set_state	= bictcp_state,

	.undo_cwnd	= bictcp_undo_cwnd,

	.min_cwnd	= bictcp_min_cwnd,

	.pkts_acked     = bictcp_acked,

	.owner		= THIS_MODULE,

	.name		= "bic",

net/ipv4/tcp_compound.c

+0 −1
Original line number Diff line number Diff line
@@ -419,7 +419,6 @@ static struct tcp_congestion_ops tcp_compound = { 
	.init		= tcp_compound_init,

	.ssthresh	= tcp_reno_ssthresh,

	.cong_avoid	= tcp_compound_cong_avoid,

	.min_cwnd	= tcp_reno_min_cwnd,

	.rtt_sample	= tcp_compound_rtt_calc,

	.set_state	= tcp_compound_state,

	.cwnd_event	= tcp_compound_cwnd_event,

net/ipv4/tcp_cong.c

+3 −3
Original line number Diff line number Diff line
@@ -38,7 +38,7 @@ int tcp_register_congestion_control(struct tcp_congestion_ops *ca) 
	int ret = 0;



	/* all algorithms must implement ssthresh and cong_avoid ops */

	if (!ca->ssthresh || !ca->cong_avoid || !ca->min_cwnd) {

	if (!ca->ssthresh || !ca->cong_avoid) {

		printk(KERN_ERR "TCP %s does not implement required ops\n",

		       ca->name);

		return -EINVAL;
@@ -251,8 +251,8 @@ u32 tcp_reno_ssthresh(struct sock *sk) 
}

EXPORT_SYMBOL_GPL(tcp_reno_ssthresh);



/* Lower bound on congestion window. */

u32 tcp_reno_min_cwnd(struct sock *sk)

/* Lower bound on congestion window with halving. */

u32 tcp_reno_min_cwnd(const struct sock *sk)

{

	const struct tcp_sock *tp = tcp_sk(sk);

	return tp->snd_ssthresh/2;

net/ipv4/tcp_cubic.c

+0 −6
Original line number Diff line number Diff line
@@ -325,11 +325,6 @@ static u32 bictcp_undo_cwnd(struct sock *sk) 
	return max(tcp_sk(sk)->snd_cwnd, ca->last_max_cwnd);

}



static u32 bictcp_min_cwnd(struct sock *sk)

{

	return tcp_sk(sk)->snd_ssthresh;

}



static void bictcp_state(struct sock *sk, u8 new_state)

{

	if (new_state == TCP_CA_Loss)
@@ -357,7 +352,6 @@ static struct tcp_congestion_ops cubictcp = { 
	.cong_avoid	= bictcp_cong_avoid,

	.set_state	= bictcp_state,

	.undo_cwnd	= bictcp_undo_cwnd,

	.min_cwnd	= bictcp_min_cwnd,

	.pkts_acked     = bictcp_acked,

	.owner		= THIS_MODULE,

	.name		= "cubic",