[linux.git] / net / ipv4 / tcp_htcp.c

/*
 * H-TCP congestion control. The algorithm is detailed in:
 * R.N.Shorten, D.J.Leith:
 *   "H-TCP: TCP for high-speed and long-distance networks"
 *   Proc. PFLDnet, Argonne, 2004.
 * http://www.hamilton.ie/net/htcp3.pdf
 */

#include <linux/mm.h>
#include <linux/module.h>
#include <net/tcp.h>

#define ALPHA_BASE	(1<<7)	/* 1.0 with shift << 7 */
#define BETA_MIN	(1<<6)	/* 0.5 with shift << 7 */
#define BETA_MAX	102	/* 0.8 with shift << 7 */

static int use_rtt_scaling __read_mostly = 1;
module_param(use_rtt_scaling, int, 0644);
MODULE_PARM_DESC(use_rtt_scaling, "turn on/off RTT scaling");

static int use_bandwidth_switch __read_mostly = 1;
module_param(use_bandwidth_switch, int, 0644);
MODULE_PARM_DESC(use_bandwidth_switch, "turn on/off bandwidth switcher");

struct htcp {
	u32	alpha;		/* Fixed point arith, << 7 */
	u8	beta;           /* Fixed point arith, << 7 */
	u8	modeswitch;	/* Delay modeswitch
				   until we had at least one congestion event */
	u16	pkts_acked;
	u32	packetcount;
	u32	minRTT;
	u32	maxRTT;
	u32	last_cong;	/* Time since last congestion event end */
	u32	undo_last_cong;

	u32	undo_maxRTT;
	u32	undo_old_maxB;

	/* Bandwidth estimation */
	u32	minB;
	u32	maxB;
	u32	old_maxB;
	u32	Bi;
	u32	lasttime;
};

static inline u32 htcp_cong_time(const struct htcp *ca)
{
	return jiffies - ca->last_cong;
}

static inline u32 htcp_ccount(const struct htcp *ca)
{
	return htcp_cong_time(ca) / ca->minRTT;
}

static inline void htcp_reset(struct htcp *ca)
{
	ca->undo_last_cong = ca->last_cong;
	ca->undo_maxRTT = ca->maxRTT;
	ca->undo_old_maxB = ca->old_maxB;

	ca->last_cong = jiffies;
}

static u32 htcp_cwnd_undo(struct sock *sk)
{
	const struct tcp_sock *tp = tcp_sk(sk);
	struct htcp *ca = inet_csk_ca(sk);

	if (ca->undo_last_cong) {
		ca->last_cong = ca->undo_last_cong;
		ca->maxRTT = ca->undo_maxRTT;
		ca->old_maxB = ca->undo_old_maxB;
		ca->undo_last_cong = 0;
	}

	return max(tp->snd_cwnd, (tp->snd_ssthresh << 7) / ca->beta);
}

static inline void measure_rtt(struct sock *sk, u32 srtt)
{
	const struct inet_connection_sock *icsk = inet_csk(sk);
	struct htcp *ca = inet_csk_ca(sk);

	/* keep track of minimum RTT seen so far, minRTT is zero at first */
	if (ca->minRTT > srtt || !ca->minRTT)
		ca->minRTT = srtt;

	/* max RTT */
	if (icsk->icsk_ca_state == TCP_CA_Open) {
		if (ca->maxRTT < ca->minRTT)
			ca->maxRTT = ca->minRTT;
		if (ca->maxRTT < srtt &&
		    srtt <= ca->maxRTT + msecs_to_jiffies(20))
			ca->maxRTT = srtt;
	}
}

static void measure_achieved_throughput(struct sock *sk,
					u32 pkts_acked, s32 rtt)
{
	const struct inet_connection_sock *icsk = inet_csk(sk);
	const struct tcp_sock *tp = tcp_sk(sk);
	struct htcp *ca = inet_csk_ca(sk);
	u32 now = tcp_time_stamp;

	if (icsk->icsk_ca_state == TCP_CA_Open)
		ca->pkts_acked = pkts_acked;

	if (rtt > 0)
		measure_rtt(sk, usecs_to_jiffies(rtt));

	if (!use_bandwidth_switch)
		return;

	/* achieved throughput calculations */
	if (!((1 << icsk->icsk_ca_state) & (TCPF_CA_Open | TCPF_CA_Disorder))) {
		ca->packetcount = 0;
		ca->lasttime = now;
		return;
	}

	ca->packetcount += pkts_acked;

	if (ca->packetcount >= tp->snd_cwnd - (ca->alpha >> 7 ? : 1) &&
	    now - ca->lasttime >= ca->minRTT &&
	    ca->minRTT > 0) {
		__u32 cur_Bi = ca->packetcount * HZ / (now - ca->lasttime);

		if (htcp_ccount(ca) <= 3) {
			/* just after backoff */
			ca->minB = ca->maxB = ca->Bi = cur_Bi;
		} else {
			ca->Bi = (3 * ca->Bi + cur_Bi) / 4;
			if (ca->Bi > ca->maxB)
				ca->maxB = ca->Bi;
			if (ca->minB > ca->maxB)
				ca->minB = ca->maxB;
		}
		ca->packetcount = 0;
		ca->lasttime = now;
	}
}

static inline void htcp_beta_update(struct htcp *ca, u32 minRTT, u32 maxRTT)
{
	if (use_bandwidth_switch) {
		u32 maxB = ca->maxB;
		u32 old_maxB = ca->old_maxB;

		ca->old_maxB = ca->maxB;
		if (!between(5 * maxB, 4 * old_maxB, 6 * old_maxB)) {
			ca->beta = BETA_MIN;
			ca->modeswitch = 0;
			return;
		}
	}

	if (ca->modeswitch && minRTT > msecs_to_jiffies(10) && maxRTT) {
		ca->beta = (minRTT << 7) / maxRTT;
		if (ca->beta < BETA_MIN)
			ca->beta = BETA_MIN;
		else if (ca->beta > BETA_MAX)
			ca->beta = BETA_MAX;
	} else {
		ca->beta = BETA_MIN;
		ca->modeswitch = 1;
	}
}

static inline void htcp_alpha_update(struct htcp *ca)
{
	u32 minRTT = ca->minRTT;
	u32 factor = 1;
	u32 diff = htcp_cong_time(ca);

	if (diff > HZ) {
		diff -= HZ;
		factor = 1 + (10 * diff + ((diff / 2) * (diff / 2) / HZ)) / HZ;
	}

	if (use_rtt_scaling && minRTT) {
		u32 scale = (HZ << 3) / (10 * minRTT);

		/* clamping ratio to interval [0.5,10]<<3 */
		scale = min(max(scale, 1U << 2), 10U << 3);
		factor = (factor << 3) / scale;
		if (!factor)
			factor = 1;
	}

	ca->alpha = 2 * factor * ((1 << 7) - ca->beta);
	if (!ca->alpha)
		ca->alpha = ALPHA_BASE;
}

/*
 * After we have the rtt data to calculate beta, we'd still prefer to wait one
 * rtt before we adjust our beta to ensure we are working from a consistent
 * data.
 *
 * This function should be called when we hit a congestion event since only at
 * that point do we really have a real sense of maxRTT (the queues en route
 * were getting just too full now).
 */
static void htcp_param_update(struct sock *sk)
{
	struct htcp *ca = inet_csk_ca(sk);
	u32 minRTT = ca->minRTT;
	u32 maxRTT = ca->maxRTT;

	htcp_beta_update(ca, minRTT, maxRTT);
	htcp_alpha_update(ca);

	/* add slowly fading memory for maxRTT to accommodate routing changes */
	if (minRTT > 0 && maxRTT > minRTT)
		ca->maxRTT = minRTT + ((maxRTT - minRTT) * 95) / 100;
}

static u32 htcp_recalc_ssthresh(struct sock *sk)
{
	const struct tcp_sock *tp = tcp_sk(sk);
	const struct htcp *ca = inet_csk_ca(sk);

	htcp_param_update(sk);
	return max((tp->snd_cwnd * ca->beta) >> 7, 2U);
}

static void htcp_cong_avoid(struct sock *sk, u32 ack, u32 acked)
{
	struct tcp_sock *tp = tcp_sk(sk);
	struct htcp *ca = inet_csk_ca(sk);

	if (!tcp_is_cwnd_limited(sk))
		return;

	if (tcp_in_slow_start(tp))
		tcp_slow_start(tp, acked);
	else {
		/* In dangerous area, increase slowly.
		 * In theory this is tp->snd_cwnd += alpha / tp->snd_cwnd
		 */
		if ((tp->snd_cwnd_cnt * ca->alpha)>>7 >= tp->snd_cwnd) {
			if (tp->snd_cwnd < tp->snd_cwnd_clamp)
				tp->snd_cwnd++;
			tp->snd_cwnd_cnt = 0;
			htcp_alpha_update(ca);
		} else
			tp->snd_cwnd_cnt += ca->pkts_acked;

		ca->pkts_acked = 1;
	}
}

static void htcp_init(struct sock *sk)
{
	struct htcp *ca = inet_csk_ca(sk);

	memset(ca, 0, sizeof(struct htcp));
	ca->alpha = ALPHA_BASE;
	ca->beta = BETA_MIN;
	ca->pkts_acked = 1;
	ca->last_cong = jiffies;
}

static void htcp_state(struct sock *sk, u8 new_state)
{
	switch (new_state) {
	case TCP_CA_Open:
		{
			struct htcp *ca = inet_csk_ca(sk);

			if (ca->undo_last_cong) {
				ca->last_cong = jiffies;
				ca->undo_last_cong = 0;
			}
		}
		break;
	case TCP_CA_CWR:
	case TCP_CA_Recovery:
	case TCP_CA_Loss:
		htcp_reset(inet_csk_ca(sk));
		break;
	}
}

static struct tcp_congestion_ops htcp __read_mostly = {
	.init		= htcp_init,
	.ssthresh	= htcp_recalc_ssthresh,
	.cong_avoid	= htcp_cong_avoid,
	.set_state	= htcp_state,
	.undo_cwnd	= htcp_cwnd_undo,
	.pkts_acked	= measure_achieved_throughput,
	.owner		= THIS_MODULE,
	.name		= "htcp",
};

static int __init htcp_register(void)
{
	BUILD_BUG_ON(sizeof(struct htcp) > ICSK_CA_PRIV_SIZE);
	BUILD_BUG_ON(BETA_MIN >= BETA_MAX);
	return tcp_register_congestion_control(&htcp);
}

static void __exit htcp_unregister(void)
{
	tcp_unregister_congestion_control(&htcp);
}

module_init(htcp_register);
module_exit(htcp_unregister);

MODULE_AUTHOR("Baruch Even");
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("H-TCP");
Commit	Line	Data
a7868ea6 BE	1	/*
	2	* H-TCP congestion control. The algorithm is detailed in:
	3	* R.N.Shorten, D.J.Leith:
	4	* "H-TCP: TCP for high-speed and long-distance networks"
	5	* Proc. PFLDnet, Argonne, 2004.
	6	* http://www.hamilton.ie/net/htcp3.pdf
	7	*/
	8
a7868ea6 BE	9	#include <linux/mm.h>
	10	#include <linux/module.h>
	11	#include <net/tcp.h>
	12
9121c777 SH	13	#define ALPHA_BASE (1<<7) /* 1.0 with shift << 7 */
9121c777 SH	14	#define BETA_MIN (1<<6) /* 0.5 with shift << 7 */
a7868ea6 BE	15	#define BETA_MAX 102 /* 0.8 with shift << 7 */
a7868ea6 BE	16
9121c777	17	static int use_rtt_scaling __read_mostly = 1;
a7868ea6 BE	18	module_param(use_rtt_scaling, int, 0644);
	19	MODULE_PARM_DESC(use_rtt_scaling, "turn on/off RTT scaling");
	20
9121c777	21	static int use_bandwidth_switch __read_mostly = 1;
a7868ea6 BE	22	module_param(use_bandwidth_switch, int, 0644);
	23	MODULE_PARM_DESC(use_bandwidth_switch, "turn on/off bandwidth switcher");
	24
	25	struct htcp {
2a272f98	26	u32 alpha; /* Fixed point arith, << 7 */
a7868ea6	27	u8 beta; /* Fixed point arith, << 7 */
9121c777 SH	28	u8 modeswitch; /* Delay modeswitch
9121c777 SH	29	until we had at least one congestion event */
0bc6d90b BE	30	u16 pkts_acked;
0bc6d90b BE	31	u32 packetcount;
a7868ea6 BE	32	u32 minRTT;
a7868ea6 BE	33	u32 maxRTT;
2404043a DM	34	u32 last_cong; /* Time since last congestion event end */
2404043a DM	35	u32 undo_last_cong;
a7868ea6 BE	36
	37	u32 undo_maxRTT;
	38	u32 undo_old_maxB;
	39
	40	/* Bandwidth estimation */
	41	u32 minB;
	42	u32 maxB;
	43	u32 old_maxB;
	44	u32 Bi;
	45	u32 lasttime;
	46	};
	47
9121c777	48	static inline u32 htcp_cong_time(const struct htcp *ca)
50bf3e22 BE	49	{
	50	return jiffies - ca->last_cong;
	51	}
	52
9121c777	53	static inline u32 htcp_ccount(const struct htcp *ca)
50bf3e22	54	{
9121c777	55	return htcp_cong_time(ca) / ca->minRTT;
50bf3e22 BE	56	}
50bf3e22 BE	57
a7868ea6 BE	58	static inline void htcp_reset(struct htcp *ca)
a7868ea6 BE	59	{
50bf3e22	60	ca->undo_last_cong = ca->last_cong;
a7868ea6 BE	61	ca->undo_maxRTT = ca->maxRTT;
	62	ca->undo_old_maxB = ca->old_maxB;
	63
50bf3e22	64	ca->last_cong = jiffies;
a7868ea6 BE	65	}
a7868ea6 BE	66
6687e988	67	static u32 htcp_cwnd_undo(struct sock *sk)
a7868ea6	68	{
6687e988 ACM	69	const struct tcp_sock *tp = tcp_sk(sk);
6687e988 ACM	70	struct htcp *ca = inet_csk_ca(sk);
9121c777	71
8f65b535 DL	72	if (ca->undo_last_cong) {
	73	ca->last_cong = ca->undo_last_cong;
	74	ca->maxRTT = ca->undo_maxRTT;
	75	ca->old_maxB = ca->undo_old_maxB;
	76	ca->undo_last_cong = 0;
	77	}
9121c777 SH	78
9121c777 SH	79	return max(tp->snd_cwnd, (tp->snd_ssthresh << 7) / ca->beta);
a7868ea6 BE	80	}
a7868ea6 BE	81
113bbbd8	82	static inline void measure_rtt(struct sock *sk, u32 srtt)
a7868ea6	83	{
6687e988	84	const struct inet_connection_sock *icsk = inet_csk(sk);
6687e988	85	struct htcp *ca = inet_csk_ca(sk);
a7868ea6 BE	86
	87	/* keep track of minimum RTT seen so far, minRTT is zero at first */
	88	if (ca->minRTT > srtt \|\| !ca->minRTT)
	89	ca->minRTT = srtt;
	90
	91	/* max RTT */
f34d1955	92	if (icsk->icsk_ca_state == TCP_CA_Open) {
a7868ea6 BE	93	if (ca->maxRTT < ca->minRTT)
a7868ea6 BE	94	ca->maxRTT = ca->minRTT;
9d4fb27d JP	95	if (ca->maxRTT < srtt &&
9d4fb27d JP	96	srtt <= ca->maxRTT + msecs_to_jiffies(20))
a7868ea6 BE	97	ca->maxRTT = srtt;
	98	}
	99	}
	100
688d1945	101	static void measure_achieved_throughput(struct sock *sk,
688d1945	102	u32 pkts_acked, s32 rtt)
a7868ea6	103	{
6687e988 ACM	104	const struct inet_connection_sock *icsk = inet_csk(sk);
	105	const struct tcp_sock *tp = tcp_sk(sk);
	106	struct htcp *ca = inet_csk_ca(sk);
a7868ea6 BE	107	u32 now = tcp_time_stamp;
a7868ea6 BE	108
0bc6d90b BE	109	if (icsk->icsk_ca_state == TCP_CA_Open)
	110	ca->pkts_acked = pkts_acked;
	111
113bbbd8 SH	112	if (rtt > 0)
	113	measure_rtt(sk, usecs_to_jiffies(rtt));
	114
0bc6d90b BE	115	if (!use_bandwidth_switch)
	116	return;
	117
a7868ea6	118	/* achieved throughput calculations */
571a5dd8	119	if (!((1 << icsk->icsk_ca_state) & (TCPF_CA_Open \| TCPF_CA_Disorder))) {
a7868ea6 BE	120	ca->packetcount = 0;
	121	ca->lasttime = now;
	122	return;
	123	}
	124
	125	ca->packetcount += pkts_acked;
	126
9d4fb27d JP	127	if (ca->packetcount >= tp->snd_cwnd - (ca->alpha >> 7 ? : 1) &&
	128	now - ca->lasttime >= ca->minRTT &&
	129	ca->minRTT > 0) {
9121c777 SH	130	__u32 cur_Bi = ca->packetcount * HZ / (now - ca->lasttime);
9121c777 SH	131
50bf3e22	132	if (htcp_ccount(ca) <= 3) {
a7868ea6 BE	133	/* just after backoff */
	134	ca->minB = ca->maxB = ca->Bi = cur_Bi;
	135	} else {
9121c777	136	ca->Bi = (3 * ca->Bi + cur_Bi) / 4;
a7868ea6 BE	137	if (ca->Bi > ca->maxB)
	138	ca->maxB = ca->Bi;
	139	if (ca->minB > ca->maxB)
	140	ca->minB = ca->maxB;
	141	}
	142	ca->packetcount = 0;
	143	ca->lasttime = now;
	144	}
	145	}
	146
	147	static inline void htcp_beta_update(struct htcp *ca, u32 minRTT, u32 maxRTT)
	148	{
	149	if (use_bandwidth_switch) {
	150	u32 maxB = ca->maxB;
	151	u32 old_maxB = ca->old_maxB;
a7868ea6	152
688d1945	153	ca->old_maxB = ca->maxB;
9121c777	154	if (!between(5 * maxB, 4 * old_maxB, 6 * old_maxB)) {
a7868ea6 BE	155	ca->beta = BETA_MIN;
	156	ca->modeswitch = 0;
	157	return;
	158	}
	159	}
	160
c33ad6e4	161	if (ca->modeswitch && minRTT > msecs_to_jiffies(10) && maxRTT) {
9121c777	162	ca->beta = (minRTT << 7) / maxRTT;
a7868ea6 BE	163	if (ca->beta < BETA_MIN)
	164	ca->beta = BETA_MIN;
	165	else if (ca->beta > BETA_MAX)
	166	ca->beta = BETA_MAX;
	167	} else {
	168	ca->beta = BETA_MIN;
	169	ca->modeswitch = 1;
	170	}
	171	}
	172
	173	static inline void htcp_alpha_update(struct htcp *ca)
	174	{
	175	u32 minRTT = ca->minRTT;
	176	u32 factor = 1;
50bf3e22	177	u32 diff = htcp_cong_time(ca);
a7868ea6 BE	178
	179	if (diff > HZ) {
	180	diff -= HZ;
9121c777	181	factor = 1 + (10 * diff + ((diff / 2) * (diff / 2) / HZ)) / HZ;
a7868ea6 BE	182	}
	183
	184	if (use_rtt_scaling && minRTT) {
9121c777 SH	185	u32 scale = (HZ << 3) / (10 * minRTT);
	186
	187	/* clamping ratio to interval [0.5,10]<<3 */
	188	scale = min(max(scale, 1U << 2), 10U << 3);
	189	factor = (factor << 3) / scale;
a7868ea6 BE	190	if (!factor)
	191	factor = 1;
	192	}
	193
9121c777	194	ca->alpha = 2 * factor * ((1 << 7) - ca->beta);
a7868ea6 BE	195	if (!ca->alpha)
	196	ca->alpha = ALPHA_BASE;
	197	}
	198
9121c777 SH	199	/*
9121c777 SH	200	* After we have the rtt data to calculate beta, we'd still prefer to wait one
a7868ea6 BE	201	* rtt before we adjust our beta to ensure we are working from a consistent
	202	* data.
	203	*
	204	* This function should be called when we hit a congestion event since only at
	205	* that point do we really have a real sense of maxRTT (the queues en route
	206	* were getting just too full now).
	207	*/
6687e988	208	static void htcp_param_update(struct sock *sk)
a7868ea6	209	{
6687e988	210	struct htcp *ca = inet_csk_ca(sk);
a7868ea6 BE	211	u32 minRTT = ca->minRTT;
	212	u32 maxRTT = ca->maxRTT;
	213
	214	htcp_beta_update(ca, minRTT, maxRTT);
	215	htcp_alpha_update(ca);
	216
9121c777	217	/* add slowly fading memory for maxRTT to accommodate routing changes */
a7868ea6	218	if (minRTT > 0 && maxRTT > minRTT)
9121c777	219	ca->maxRTT = minRTT + ((maxRTT - minRTT) * 95) / 100;
a7868ea6 BE	220	}
a7868ea6 BE	221
6687e988	222	static u32 htcp_recalc_ssthresh(struct sock *sk)
a7868ea6	223	{
6687e988 ACM	224	const struct tcp_sock *tp = tcp_sk(sk);
6687e988 ACM	225	const struct htcp *ca = inet_csk_ca(sk);
9121c777	226
6687e988	227	htcp_param_update(sk);
a7868ea6 BE	228	return max((tp->snd_cwnd * ca->beta) >> 7, 2U);
	229	}
	230
24901551	231	static void htcp_cong_avoid(struct sock *sk, u32 ack, u32 acked)
a7868ea6	232	{
6687e988 ACM	233	struct tcp_sock *tp = tcp_sk(sk);
6687e988 ACM	234	struct htcp *ca = inet_csk_ca(sk);
a7868ea6	235
24901551	236	if (!tcp_is_cwnd_limited(sk))
a7868ea6 BE	237	return;
a7868ea6 BE	238
071d5080	239	if (tcp_in_slow_start(tp))
9f9843a7	240	tcp_slow_start(tp, acked);
7faffa1c	241	else {
7faffa1c	242	/* In dangerous area, increase slowly.
a7868ea6 BE	243	* In theory this is tp->snd_cwnd += alpha / tp->snd_cwnd
a7868ea6 BE	244	*/
0bc6d90b	245	if ((tp->snd_cwnd_cnt * ca->alpha)>>7 >= tp->snd_cwnd) {
a7868ea6 BE	246	if (tp->snd_cwnd < tp->snd_cwnd_clamp)
	247	tp->snd_cwnd++;
	248	tp->snd_cwnd_cnt = 0;
50bf3e22	249	htcp_alpha_update(ca);
0bc6d90b BE	250	} else
	251	tp->snd_cwnd_cnt += ca->pkts_acked;
	252
	253	ca->pkts_acked = 1;
a7868ea6 BE	254	}
	255	}
	256
6687e988	257	static void htcp_init(struct sock *sk)
a7868ea6	258	{
6687e988	259	struct htcp *ca = inet_csk_ca(sk);
a7868ea6 BE	260
	261	memset(ca, 0, sizeof(struct htcp));
	262	ca->alpha = ALPHA_BASE;
	263	ca->beta = BETA_MIN;
0bc6d90b	264	ca->pkts_acked = 1;
50bf3e22	265	ca->last_cong = jiffies;
a7868ea6 BE	266	}
a7868ea6 BE	267
6687e988	268	static void htcp_state(struct sock *sk, u8 new_state)
a7868ea6 BE	269	{
a7868ea6 BE	270	switch (new_state) {
50bf3e22 BE	271	case TCP_CA_Open:
	272	{
	273	struct htcp *ca = inet_csk_ca(sk);
688d1945	274
8f65b535 DL	275	if (ca->undo_last_cong) {
	276	ca->last_cong = jiffies;
	277	ca->undo_last_cong = 0;
	278	}
50bf3e22 BE	279	}
50bf3e22 BE	280	break;
a7868ea6 BE	281	case TCP_CA_CWR:
	282	case TCP_CA_Recovery:
	283	case TCP_CA_Loss:
6687e988	284	htcp_reset(inet_csk_ca(sk));
a7868ea6 BE	285	break;
	286	}
	287	}
	288
a252bebe	289	static struct tcp_congestion_ops htcp __read_mostly = {
a7868ea6 BE	290	.init = htcp_init,
a7868ea6 BE	291	.ssthresh = htcp_recalc_ssthresh,
a7868ea6 BE	292	.cong_avoid = htcp_cong_avoid,
	293	.set_state = htcp_state,
	294	.undo_cwnd = htcp_cwnd_undo,
	295	.pkts_acked = measure_achieved_throughput,
	296	.owner = THIS_MODULE,
	297	.name = "htcp",
	298	};
	299
	300	static int __init htcp_register(void)
	301	{
74975d40	302	BUILD_BUG_ON(sizeof(struct htcp) > ICSK_CA_PRIV_SIZE);
a7868ea6	303	BUILD_BUG_ON(BETA_MIN >= BETA_MAX);
a7868ea6 BE	304	return tcp_register_congestion_control(&htcp);
	305	}
	306
	307	static void __exit htcp_unregister(void)
	308	{
	309	tcp_unregister_congestion_control(&htcp);
	310	}
	311
	312	module_init(htcp_register);
	313	module_exit(htcp_unregister);
	314
	315	MODULE_AUTHOR("Baruch Even");
	316	MODULE_LICENSE("GPL");
	317	MODULE_DESCRIPTION("H-TCP");