[mirror_ubuntu-artful-kernel.git] / net / ipv4 / tcp_illinois.c

/*
 * TCP Illinois congestion control.
 * Home page:
 *	http://www.ews.uiuc.edu/~shaoliu/tcpillinois/index.html
 *
 * The algorithm is described in:
 * "TCP-Illinois: A Loss and Delay-Based Congestion Control Algorithm
 *  for High-Speed Networks"
 * http://www.ifp.illinois.edu/~srikant/Papers/liubassri06perf.pdf
 *
 * Implemented from description in paper and ns-2 simulation.
 * Copyright (C) 2007 Stephen Hemminger <shemminger@linux-foundation.org>
 */

#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/inet_diag.h>
#include <asm/div64.h>
#include <net/tcp.h>

#define ALPHA_SHIFT	7
#define ALPHA_SCALE	(1u<<ALPHA_SHIFT)
#define ALPHA_MIN	((3*ALPHA_SCALE)/10)	/* ~0.3 */
#define ALPHA_MAX	(10*ALPHA_SCALE)	/* 10.0 */
#define ALPHA_BASE	ALPHA_SCALE		/* 1.0 */
#define RTT_MAX		(U32_MAX / ALPHA_MAX)	/* 3.3 secs */

#define BETA_SHIFT	6
#define BETA_SCALE	(1u<<BETA_SHIFT)
#define BETA_MIN	(BETA_SCALE/8)		/* 0.125 */
#define BETA_MAX	(BETA_SCALE/2)		/* 0.5 */
#define BETA_BASE	BETA_MAX

static int win_thresh __read_mostly = 15;
module_param(win_thresh, int, 0);
MODULE_PARM_DESC(win_thresh, "Window threshold for starting adaptive sizing");

static int theta __read_mostly = 5;
module_param(theta, int, 0);
MODULE_PARM_DESC(theta, "# of fast RTT's before full growth");

/* TCP Illinois Parameters */
struct illinois {
	u64	sum_rtt;	/* sum of rtt's measured within last rtt */
	u16	cnt_rtt;	/* # of rtts measured within last rtt */
	u32	base_rtt;	/* min of all rtt in usec */
	u32	max_rtt;	/* max of all rtt in usec */
	u32	end_seq;	/* right edge of current RTT */
	u32	alpha;		/* Additive increase */
	u32	beta;		/* Muliplicative decrease */
	u32	loss_cwnd;	/* cwnd on loss */
	u16	acked;		/* # packets acked by current ACK */
	u8	rtt_above;	/* average rtt has gone above threshold */
	u8	rtt_low;	/* # of rtts measurements below threshold */
};

static void rtt_reset(struct sock *sk)
{
	struct tcp_sock *tp = tcp_sk(sk);
	struct illinois *ca = inet_csk_ca(sk);

	ca->end_seq = tp->snd_nxt;
	ca->cnt_rtt = 0;
	ca->sum_rtt = 0;

	/* TODO: age max_rtt? */
}

static void tcp_illinois_init(struct sock *sk)
{
	struct illinois *ca = inet_csk_ca(sk);

	ca->alpha = ALPHA_MAX;
	ca->beta = BETA_BASE;
	ca->base_rtt = 0x7fffffff;
	ca->max_rtt = 0;

	ca->acked = 0;
	ca->rtt_low = 0;
	ca->rtt_above = 0;

	rtt_reset(sk);
}

/* Measure RTT for each ack. */
static void tcp_illinois_acked(struct sock *sk, const struct ack_sample *sample)
{
	struct illinois *ca = inet_csk_ca(sk);
	s32 rtt_us = sample->rtt_us;

	ca->acked = sample->pkts_acked;

	/* dup ack, no rtt sample */
	if (rtt_us < 0)
		return;

	/* ignore bogus values, this prevents wraparound in alpha math */
	if (rtt_us > RTT_MAX)
		rtt_us = RTT_MAX;

	/* keep track of minimum RTT seen so far */
	if (ca->base_rtt > rtt_us)
		ca->base_rtt = rtt_us;

	/* and max */
	if (ca->max_rtt < rtt_us)
		ca->max_rtt = rtt_us;

	++ca->cnt_rtt;
	ca->sum_rtt += rtt_us;
}

/* Maximum queuing delay */
static inline u32 max_delay(const struct illinois *ca)
{
	return ca->max_rtt - ca->base_rtt;
}

/* Average queuing delay */
static inline u32 avg_delay(const struct illinois *ca)
{
	u64 t = ca->sum_rtt;

	do_div(t, ca->cnt_rtt);
	return t - ca->base_rtt;
}

/*
 * Compute value of alpha used for additive increase.
 * If small window then use 1.0, equivalent to Reno.
 *
 * For larger windows, adjust based on average delay.
 * A. If average delay is at minimum (we are uncongested),
 *    then use large alpha (10.0) to increase faster.
 * B. If average delay is at maximum (getting congested)
 *    then use small alpha (0.3)
 *
 * The result is a convex window growth curve.
 */
static u32 alpha(struct illinois *ca, u32 da, u32 dm)
{
	u32 d1 = dm / 100;	/* Low threshold */

	if (da <= d1) {
		/* If never got out of low delay zone, then use max */
		if (!ca->rtt_above)
			return ALPHA_MAX;

		/* Wait for 5 good RTT's before allowing alpha to go alpha max.
		 * This prevents one good RTT from causing sudden window increase.
		 */
		if (++ca->rtt_low < theta)
			return ca->alpha;

		ca->rtt_low = 0;
		ca->rtt_above = 0;
		return ALPHA_MAX;
	}

	ca->rtt_above = 1;

	/*
	 * Based on:
	 *
	 *      (dm - d1) amin amax
	 * k1 = -------------------
	 *         amax - amin
	 *
	 *       (dm - d1) amin
	 * k2 = ----------------  - d1
	 *        amax - amin
	 *
	 *             k1
	 * alpha = ----------
	 *          k2 + da
	 */

	dm -= d1;
	da -= d1;
	return (dm * ALPHA_MAX) /
		(dm + (da  * (ALPHA_MAX - ALPHA_MIN)) / ALPHA_MIN);
}

/*
 * Beta used for multiplicative decrease.
 * For small window sizes returns same value as Reno (0.5)
 *
 * If delay is small (10% of max) then beta = 1/8
 * If delay is up to 80% of max then beta = 1/2
 * In between is a linear function
 */
static u32 beta(u32 da, u32 dm)
{
	u32 d2, d3;

	d2 = dm / 10;
	if (da <= d2)
		return BETA_MIN;

	d3 = (8 * dm) / 10;
	if (da >= d3 || d3 <= d2)
		return BETA_MAX;

	/*
	 * Based on:
	 *
	 *       bmin d3 - bmax d2
	 * k3 = -------------------
	 *         d3 - d2
	 *
	 *       bmax - bmin
	 * k4 = -------------
	 *         d3 - d2
	 *
	 * b = k3 + k4 da
	 */
	return (BETA_MIN * d3 - BETA_MAX * d2 + (BETA_MAX - BETA_MIN) * da)
		/ (d3 - d2);
}

/* Update alpha and beta values once per RTT */
static void update_params(struct sock *sk)
{
	struct tcp_sock *tp = tcp_sk(sk);
	struct illinois *ca = inet_csk_ca(sk);

	if (tp->snd_cwnd < win_thresh) {
		ca->alpha = ALPHA_BASE;
		ca->beta = BETA_BASE;
	} else if (ca->cnt_rtt > 0) {
		u32 dm = max_delay(ca);
		u32 da = avg_delay(ca);

		ca->alpha = alpha(ca, da, dm);
		ca->beta = beta(da, dm);
	}

	rtt_reset(sk);
}

/*
 * In case of loss, reset to default values
 */
static void tcp_illinois_state(struct sock *sk, u8 new_state)
{
	struct illinois *ca = inet_csk_ca(sk);

	if (new_state == TCP_CA_Loss) {
		ca->alpha = ALPHA_BASE;
		ca->beta = BETA_BASE;
		ca->rtt_low = 0;
		ca->rtt_above = 0;
		rtt_reset(sk);
	}
}

/*
 * Increase window in response to successful acknowledgment.
 */
static void tcp_illinois_cong_avoid(struct sock *sk, u32 ack, u32 acked)
{
	struct tcp_sock *tp = tcp_sk(sk);
	struct illinois *ca = inet_csk_ca(sk);

	if (after(ack, ca->end_seq))
		update_params(sk);

	/* RFC2861 only increase cwnd if fully utilized */
	if (!tcp_is_cwnd_limited(sk))
		return;

	/* In slow start */
	if (tcp_in_slow_start(tp))
		tcp_slow_start(tp, acked);

	else {
		u32 delta;

		/* snd_cwnd_cnt is # of packets since last cwnd increment */
		tp->snd_cwnd_cnt += ca->acked;
		ca->acked = 1;

		/* This is close approximation of:
		 * tp->snd_cwnd += alpha/tp->snd_cwnd
		*/
		delta = (tp->snd_cwnd_cnt * ca->alpha) >> ALPHA_SHIFT;
		if (delta >= tp->snd_cwnd) {
			tp->snd_cwnd = min(tp->snd_cwnd + delta / tp->snd_cwnd,
					   (u32)tp->snd_cwnd_clamp);
			tp->snd_cwnd_cnt = 0;
		}
	}
}

static u32 tcp_illinois_ssthresh(struct sock *sk)
{
	struct tcp_sock *tp = tcp_sk(sk);
	struct illinois *ca = inet_csk_ca(sk);

	ca->loss_cwnd = tp->snd_cwnd;
	/* Multiplicative decrease */
	return max(tp->snd_cwnd - ((tp->snd_cwnd * ca->beta) >> BETA_SHIFT), 2U);
}

static u32 tcp_illinois_cwnd_undo(struct sock *sk)
{
	const struct illinois *ca = inet_csk_ca(sk);

	return max(tcp_sk(sk)->snd_cwnd, ca->loss_cwnd);
}

/* Extract info for Tcp socket info provided via netlink. */
static size_t tcp_illinois_info(struct sock *sk, u32 ext, int *attr,
				union tcp_cc_info *info)
{
	const struct illinois *ca = inet_csk_ca(sk);

	if (ext & (1 << (INET_DIAG_VEGASINFO - 1))) {
		info->vegas.tcpv_enabled = 1;
		info->vegas.tcpv_rttcnt = ca->cnt_rtt;
		info->vegas.tcpv_minrtt = ca->base_rtt;
		info->vegas.tcpv_rtt = 0;

		if (info->vegas.tcpv_rttcnt > 0) {
			u64 t = ca->sum_rtt;

			do_div(t, info->vegas.tcpv_rttcnt);
			info->vegas.tcpv_rtt = t;
		}
		*attr = INET_DIAG_VEGASINFO;
		return sizeof(struct tcpvegas_info);
	}
	return 0;
}

static struct tcp_congestion_ops tcp_illinois __read_mostly = {
	.init		= tcp_illinois_init,
	.ssthresh	= tcp_illinois_ssthresh,
	.undo_cwnd	= tcp_illinois_cwnd_undo,
	.cong_avoid	= tcp_illinois_cong_avoid,
	.set_state	= tcp_illinois_state,
	.get_info	= tcp_illinois_info,
	.pkts_acked	= tcp_illinois_acked,

	.owner		= THIS_MODULE,
	.name		= "illinois",
};

static int __init tcp_illinois_register(void)
{
	BUILD_BUG_ON(sizeof(struct illinois) > ICSK_CA_PRIV_SIZE);
	return tcp_register_congestion_control(&tcp_illinois);
}

static void __exit tcp_illinois_unregister(void)
{
	tcp_unregister_congestion_control(&tcp_illinois);
}

module_init(tcp_illinois_register);
module_exit(tcp_illinois_unregister);

MODULE_AUTHOR("Stephen Hemminger, Shao Liu");
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("TCP Illinois");
MODULE_VERSION("1.0");
Commit	Line	Data
c462238d SH	1	/*
	2	* TCP Illinois congestion control.
	3	* Home page:
	4	* http://www.ews.uiuc.edu/~shaoliu/tcpillinois/index.html
	5	*
	6	* The algorithm is described in:
	7	* "TCP-Illinois: A Loss and Delay-Based Congestion Control Algorithm
	8	* for High-Speed Networks"
631dd1a8	9	* http://www.ifp.illinois.edu/~srikant/Papers/liubassri06perf.pdf
c462238d SH	10	*
	11	* Implemented from description in paper and ns-2 simulation.
	12	* Copyright (C) 2007 Stephen Hemminger <shemminger@linux-foundation.org>
	13	*/
	14
	15	#include <linux/module.h>
	16	#include <linux/skbuff.h>
	17	#include <linux/inet_diag.h>
	18	#include <asm/div64.h>
	19	#include <net/tcp.h>
	20
	21	#define ALPHA_SHIFT 7
	22	#define ALPHA_SCALE (1u<<ALPHA_SHIFT)
	23	#define ALPHA_MIN ((3ALPHA_SCALE)/10) / ~0.3 */
	24	#define ALPHA_MAX (10ALPHA_SCALE) / 10.0 */
	25	#define ALPHA_BASE ALPHA_SCALE /* 1.0 */
65d1b4a7	26	#define RTT_MAX (U32_MAX / ALPHA_MAX) /* 3.3 secs */
c462238d SH	27
	28	#define BETA_SHIFT 6
	29	#define BETA_SCALE (1u<<BETA_SHIFT)
65d1b4a7 SH	30	#define BETA_MIN (BETA_SCALE/8) /* 0.125 */
	31	#define BETA_MAX (BETA_SCALE/2) /* 0.5 */
	32	#define BETA_BASE BETA_MAX
c462238d SH	33
c462238d SH	34	static int win_thresh __read_mostly = 15;
65d1b4a7	35	module_param(win_thresh, int, 0);
c462238d SH	36	MODULE_PARM_DESC(win_thresh, "Window threshold for starting adaptive sizing");
c462238d SH	37
65d1b4a7 SH	38	static int theta __read_mostly = 5;
	39	module_param(theta, int, 0);
	40	MODULE_PARM_DESC(theta, "# of fast RTT's before full growth");
c462238d SH	41
c462238d SH	42	/* TCP Illinois Parameters */
65d1b4a7 SH	43	struct illinois {
	44	u64 sum_rtt; /* sum of rtt's measured within last rtt */
	45	u16 cnt_rtt; /* # of rtts measured within last rtt */
	46	u32 base_rtt; /* min of all rtt in usec */
	47	u32 max_rtt; /* max of all rtt in usec */
	48	u32 end_seq; /* right edge of current RTT */
	49	u32 alpha; /* Additive increase */
	50	u32 beta; /* Muliplicative decrease */
85f7e750	51	u32 loss_cwnd; /* cwnd on loss */
65d1b4a7 SH	52	u16 acked; /* # packets acked by current ACK */
	53	u8 rtt_above; /* average rtt has gone above threshold */
	54	u8 rtt_low; /* # of rtts measurements below threshold */
c462238d SH	55	};
c462238d SH	56
65d1b4a7 SH	57	static void rtt_reset(struct sock *sk)
	58	{
	59	struct tcp_sock *tp = tcp_sk(sk);
	60	struct illinois *ca = inet_csk_ca(sk);
	61
	62	ca->end_seq = tp->snd_nxt;
	63	ca->cnt_rtt = 0;
	64	ca->sum_rtt = 0;
	65
	66	/* TODO: age max_rtt? */
	67	}
	68
c462238d SH	69	static void tcp_illinois_init(struct sock *sk)
c462238d SH	70	{
65d1b4a7 SH	71	struct illinois *ca = inet_csk_ca(sk);
	72
	73	ca->alpha = ALPHA_MAX;
	74	ca->beta = BETA_BASE;
	75	ca->base_rtt = 0x7fffffff;
	76	ca->max_rtt = 0;
	77
	78	ca->acked = 0;
	79	ca->rtt_low = 0;
	80	ca->rtt_above = 0;
c462238d	81
65d1b4a7	82	rtt_reset(sk);
c462238d SH	83	}
c462238d SH	84
65d1b4a7	85	/* Measure RTT for each ack. */
756ee172	86	static void tcp_illinois_acked(struct sock sk, const struct ack_sample sample)
c462238d	87	{
65d1b4a7	88	struct illinois *ca = inet_csk_ca(sk);
756ee172	89	s32 rtt_us = sample->rtt_us;
164891aa	90
756ee172	91	ca->acked = sample->pkts_acked;
164891aa	92
30cfd0ba	93	/* dup ack, no rtt sample */
756ee172	94	if (rtt_us < 0)
b9ce204f IJ	95	return;
b9ce204f IJ	96
65d1b4a7	97	/* ignore bogus values, this prevents wraparound in alpha math */
756ee172 LB	98	if (rtt_us > RTT_MAX)
756ee172 LB	99	rtt_us = RTT_MAX;
c462238d	100
65d1b4a7	101	/* keep track of minimum RTT seen so far */
756ee172 LB	102	if (ca->base_rtt > rtt_us)
756ee172 LB	103	ca->base_rtt = rtt_us;
65d1b4a7 SH	104
65d1b4a7 SH	105	/* and max */
756ee172 LB	106	if (ca->max_rtt < rtt_us)
756ee172 LB	107	ca->max_rtt = rtt_us;
c462238d	108
65d1b4a7	109	++ca->cnt_rtt;
756ee172	110	ca->sum_rtt += rtt_us;
c462238d SH	111	}
c462238d SH	112
65d1b4a7 SH	113	/* Maximum queuing delay */
65d1b4a7 SH	114	static inline u32 max_delay(const struct illinois *ca)
c462238d	115	{
65d1b4a7 SH	116	return ca->max_rtt - ca->base_rtt;
65d1b4a7 SH	117	}
c462238d	118
65d1b4a7 SH	119	/* Average queuing delay */
	120	static inline u32 avg_delay(const struct illinois *ca)
	121	{
	122	u64 t = ca->sum_rtt;
c462238d	123
65d1b4a7 SH	124	do_div(t, ca->cnt_rtt);
65d1b4a7 SH	125	return t - ca->base_rtt;
c462238d SH	126	}
	127
	128	/*
	129	* Compute value of alpha used for additive increase.
	130	* If small window then use 1.0, equivalent to Reno.
	131	*
	132	* For larger windows, adjust based on average delay.
	133	* A. If average delay is at minimum (we are uncongested),
	134	* then use large alpha (10.0) to increase faster.
	135	* B. If average delay is at maximum (getting congested)
65d1b4a7	136	* then use small alpha (0.3)
c462238d SH	137	*
	138	* The result is a convex window growth curve.
	139	*/
65d1b4a7	140	static u32 alpha(struct illinois *ca, u32 da, u32 dm)
c462238d	141	{
65d1b4a7	142	u32 d1 = dm / 100; /* Low threshold */
c462238d	143
c462238d	144	if (da <= d1) {
65d1b4a7 SH	145	/* If never got out of low delay zone, then use max */
65d1b4a7 SH	146	if (!ca->rtt_above)
c462238d	147	return ALPHA_MAX;
65d1b4a7 SH	148
	149	/* Wait for 5 good RTT's before allowing alpha to go alpha max.
	150	* This prevents one good RTT from causing sudden window increase.
	151	*/
	152	if (++ca->rtt_low < theta)
	153	return ca->alpha;
	154
	155	ca->rtt_low = 0;
	156	ca->rtt_above = 0;
	157	return ALPHA_MAX;
c462238d SH	158	}
c462238d SH	159
65d1b4a7	160	ca->rtt_above = 1;
c462238d SH	161
	162	/*
	163	* Based on:
	164	*
	165	* (dm - d1) amin amax
	166	* k1 = -------------------
	167	* amax - amin
	168	*
	169	* (dm - d1) amin
	170	* k2 = ---------------- - d1
	171	* amax - amin
	172	*
	173	* k1
	174	* alpha = ----------
	175	* k2 + da
	176	*/
	177
	178	dm -= d1;
	179	da -= d1;
65d1b4a7 SH	180	return (dm * ALPHA_MAX) /
65d1b4a7 SH	181	(dm + (da * (ALPHA_MAX - ALPHA_MIN)) / ALPHA_MIN);
c462238d SH	182	}
	183
	184	/*
	185	* Beta used for multiplicative decrease.
	186	* For small window sizes returns same value as Reno (0.5)
	187	*
	188	* If delay is small (10% of max) then beta = 1/8
	189	* If delay is up to 80% of max then beta = 1/2
	190	* In between is a linear function
	191	*/
65d1b4a7	192	static u32 beta(u32 da, u32 dm)
c462238d	193	{
c462238d SH	194	u32 d2, d3;
c462238d SH	195
c462238d SH	196	d2 = dm / 10;
	197	if (da <= d2)
	198	return BETA_MIN;
65d1b4a7	199
c462238d SH	200	d3 = (8 * dm) / 10;
	201	if (da >= d3 \|\| d3 <= d2)
	202	return BETA_MAX;
	203
	204	/*
	205	* Based on:
	206	*
	207	* bmin d3 - bmax d2
	208	* k3 = -------------------
	209	* d3 - d2
	210	*
	211	* bmax - bmin
	212	* k4 = -------------
	213	* d3 - d2
	214	*
	215	* b = k3 + k4 da
	216	*/
	217	return (BETA_MIN * d3 - BETA_MAX * d2 + (BETA_MAX - BETA_MIN) * da)
	218	/ (d3 - d2);
	219	}
	220
65d1b4a7 SH	221	/* Update alpha and beta values once per RTT */
	222	static void update_params(struct sock *sk)
	223	{
	224	struct tcp_sock *tp = tcp_sk(sk);
	225	struct illinois *ca = inet_csk_ca(sk);
	226
	227	if (tp->snd_cwnd < win_thresh) {
	228	ca->alpha = ALPHA_BASE;
	229	ca->beta = BETA_BASE;
	230	} else if (ca->cnt_rtt > 0) {
	231	u32 dm = max_delay(ca);
	232	u32 da = avg_delay(ca);
	233
	234	ca->alpha = alpha(ca, da, dm);
	235	ca->beta = beta(da, dm);
	236	}
	237
	238	rtt_reset(sk);
	239	}
	240
	241	/*
	242	* In case of loss, reset to default values
	243	*/
	244	static void tcp_illinois_state(struct sock *sk, u8 new_state)
	245	{
	246	struct illinois *ca = inet_csk_ca(sk);
	247
	248	if (new_state == TCP_CA_Loss) {
	249	ca->alpha = ALPHA_BASE;
	250	ca->beta = BETA_BASE;
	251	ca->rtt_low = 0;
	252	ca->rtt_above = 0;
	253	rtt_reset(sk);
	254	}
	255	}
	256
	257	/*
	258	* Increase window in response to successful acknowledgment.
	259	*/
24901551	260	static void tcp_illinois_cong_avoid(struct sock *sk, u32 ack, u32 acked)
65d1b4a7 SH	261	{
	262	struct tcp_sock *tp = tcp_sk(sk);
	263	struct illinois *ca = inet_csk_ca(sk);
	264
	265	if (after(ack, ca->end_seq))
	266	update_params(sk);
	267
	268	/* RFC2861 only increase cwnd if fully utilized */
24901551	269	if (!tcp_is_cwnd_limited(sk))
65d1b4a7 SH	270	return;
	271
	272	/* In slow start */
071d5080	273	if (tcp_in_slow_start(tp))
9f9843a7	274	tcp_slow_start(tp, acked);
65d1b4a7 SH	275
	276	else {
	277	u32 delta;
	278
	279	/* snd_cwnd_cnt is # of packets since last cwnd increment */
	280	tp->snd_cwnd_cnt += ca->acked;
	281	ca->acked = 1;
	282
	283	/* This is close approximation of:
	284	* tp->snd_cwnd += alpha/tp->snd_cwnd
	285	*/
	286	delta = (tp->snd_cwnd_cnt * ca->alpha) >> ALPHA_SHIFT;
	287	if (delta >= tp->snd_cwnd) {
	288	tp->snd_cwnd = min(tp->snd_cwnd + delta / tp->snd_cwnd,
688d1945	289	(u32)tp->snd_cwnd_clamp);
65d1b4a7 SH	290	tp->snd_cwnd_cnt = 0;
	291	}
	292	}
	293	}
	294
c462238d SH	295	static u32 tcp_illinois_ssthresh(struct sock *sk)
	296	{
	297	struct tcp_sock *tp = tcp_sk(sk);
65d1b4a7	298	struct illinois *ca = inet_csk_ca(sk);
c462238d	299
85f7e750	300	ca->loss_cwnd = tp->snd_cwnd;
c462238d	301	/* Multiplicative decrease */
a357dde9	302	return max(tp->snd_cwnd - ((tp->snd_cwnd * ca->beta) >> BETA_SHIFT), 2U);
c462238d SH	303	}
c462238d SH	304
85f7e750 FW	305	static u32 tcp_illinois_cwnd_undo(struct sock *sk)
	306	{
	307	const struct illinois *ca = inet_csk_ca(sk);
	308
	309	return max(tcp_sk(sk)->snd_cwnd, ca->loss_cwnd);
	310	}
	311
65d1b4a7	312	/* Extract info for Tcp socket info provided via netlink. */
64f40ff5 ED	313	static size_t tcp_illinois_info(struct sock sk, u32 ext, int attr,
64f40ff5 ED	314	union tcp_cc_info *info)
c462238d	315	{
65d1b4a7	316	const struct illinois *ca = inet_csk_ca(sk);
c462238d SH	317
c462238d SH	318	if (ext & (1 << (INET_DIAG_VEGASINFO - 1))) {
64f40ff5 ED	319	info->vegas.tcpv_enabled = 1;
	320	info->vegas.tcpv_rttcnt = ca->cnt_rtt;
	321	info->vegas.tcpv_minrtt = ca->base_rtt;
	322	info->vegas.tcpv_rtt = 0;
65d1b4a7	323
64f40ff5	324	if (info->vegas.tcpv_rttcnt > 0) {
8f363b77	325	u64 t = ca->sum_rtt;
c462238d	326
64f40ff5 ED	327	do_div(t, info->vegas.tcpv_rttcnt);
64f40ff5 ED	328	info->vegas.tcpv_rtt = t;
8f363b77	329	}
64f40ff5 ED	330	*attr = INET_DIAG_VEGASINFO;
64f40ff5 ED	331	return sizeof(struct tcpvegas_info);
c462238d	332	}
521f1cf1	333	return 0;
c462238d SH	334	}
c462238d SH	335
a252bebe	336	static struct tcp_congestion_ops tcp_illinois __read_mostly = {
c462238d SH	337	.init = tcp_illinois_init,
c462238d SH	338	.ssthresh = tcp_illinois_ssthresh,
85f7e750	339	.undo_cwnd = tcp_illinois_cwnd_undo,
c462238d	340	.cong_avoid = tcp_illinois_cong_avoid,
65d1b4a7	341	.set_state = tcp_illinois_state,
65d1b4a7 SH	342	.get_info = tcp_illinois_info,
65d1b4a7 SH	343	.pkts_acked = tcp_illinois_acked,
c462238d SH	344
	345	.owner = THIS_MODULE,
	346	.name = "illinois",
	347	};
	348
	349	static int __init tcp_illinois_register(void)
	350	{
65d1b4a7	351	BUILD_BUG_ON(sizeof(struct illinois) > ICSK_CA_PRIV_SIZE);
c462238d SH	352	return tcp_register_congestion_control(&tcp_illinois);
	353	}
	354
	355	static void __exit tcp_illinois_unregister(void)
	356	{
	357	tcp_unregister_congestion_control(&tcp_illinois);
	358	}
	359
	360	module_init(tcp_illinois_register);
	361	module_exit(tcp_illinois_unregister);
	362
	363	MODULE_AUTHOR("Stephen Hemminger, Shao Liu");
	364	MODULE_LICENSE("GPL");
	365	MODULE_DESCRIPTION("TCP Illinois");
65d1b4a7	366	MODULE_VERSION("1.0");