Linux Audio

Check our new training course

Loading...
v6.8
  1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * TCP Veno congestion control
  4 *
  5 * This is based on the congestion detection/avoidance scheme described in
  6 *    C. P. Fu, S. C. Liew.
  7 *    "TCP Veno: TCP Enhancement for Transmission over Wireless Access Networks."
  8 *    IEEE Journal on Selected Areas in Communication,
  9 *    Feb. 2003.
 10 * 	See https://www.ie.cuhk.edu.hk/fileadmin/staff_upload/soung/Journal/J3.pdf
 11 */
 12
 13#include <linux/mm.h>
 14#include <linux/module.h>
 15#include <linux/skbuff.h>
 16#include <linux/inet_diag.h>
 17
 18#include <net/tcp.h>
 19
 20/* Default values of the Veno variables, in fixed-point representation
 21 * with V_PARAM_SHIFT bits to the right of the binary point.
 22 */
 23#define V_PARAM_SHIFT 1
 24static const int beta = 3 << V_PARAM_SHIFT;
 25
 26/* Veno variables */
 27struct veno {
 28	u8 doing_veno_now;	/* if true, do veno for this rtt */
 29	u16 cntrtt;		/* # of rtts measured within last rtt */
 30	u32 minrtt;		/* min of rtts measured within last rtt (in usec) */
 31	u32 basertt;		/* the min of all Veno rtt measurements seen (in usec) */
 32	u32 inc;		/* decide whether to increase cwnd */
 33	u32 diff;		/* calculate the diff rate */
 34};
 35
 36/* There are several situations when we must "re-start" Veno:
 37 *
 38 *  o when a connection is established
 39 *  o after an RTO
 40 *  o after fast recovery
 41 *  o when we send a packet and there is no outstanding
 42 *    unacknowledged data (restarting an idle connection)
 43 *
 44 */
 45static inline void veno_enable(struct sock *sk)
 46{
 47	struct veno *veno = inet_csk_ca(sk);
 48
 49	/* turn on Veno */
 50	veno->doing_veno_now = 1;
 51
 52	veno->minrtt = 0x7fffffff;
 53}
 54
 55static inline void veno_disable(struct sock *sk)
 56{
 57	struct veno *veno = inet_csk_ca(sk);
 58
 59	/* turn off Veno */
 60	veno->doing_veno_now = 0;
 61}
 62
 63static void tcp_veno_init(struct sock *sk)
 64{
 65	struct veno *veno = inet_csk_ca(sk);
 66
 67	veno->basertt = 0x7fffffff;
 68	veno->inc = 1;
 69	veno_enable(sk);
 70}
 71
 72/* Do rtt sampling needed for Veno. */
 73static void tcp_veno_pkts_acked(struct sock *sk,
 74				const struct ack_sample *sample)
 75{
 76	struct veno *veno = inet_csk_ca(sk);
 77	u32 vrtt;
 78
 79	if (sample->rtt_us < 0)
 80		return;
 81
 82	/* Never allow zero rtt or baseRTT */
 83	vrtt = sample->rtt_us + 1;
 84
 85	/* Filter to find propagation delay: */
 86	if (vrtt < veno->basertt)
 87		veno->basertt = vrtt;
 88
 89	/* Find the min rtt during the last rtt to find
 90	 * the current prop. delay + queuing delay:
 91	 */
 92	veno->minrtt = min(veno->minrtt, vrtt);
 93	veno->cntrtt++;
 94}
 95
 96static void tcp_veno_state(struct sock *sk, u8 ca_state)
 97{
 98	if (ca_state == TCP_CA_Open)
 99		veno_enable(sk);
100	else
101		veno_disable(sk);
102}
103
104/*
105 * If the connection is idle and we are restarting,
106 * then we don't want to do any Veno calculations
107 * until we get fresh rtt samples.  So when we
108 * restart, we reset our Veno state to a clean
109 * state. After we get acks for this flight of
110 * packets, _then_ we can make Veno calculations
111 * again.
112 */
113static void tcp_veno_cwnd_event(struct sock *sk, enum tcp_ca_event event)
114{
115	if (event == CA_EVENT_CWND_RESTART || event == CA_EVENT_TX_START)
116		tcp_veno_init(sk);
117}
118
119static void tcp_veno_cong_avoid(struct sock *sk, u32 ack, u32 acked)
120{
121	struct tcp_sock *tp = tcp_sk(sk);
122	struct veno *veno = inet_csk_ca(sk);
123
124	if (!veno->doing_veno_now) {
125		tcp_reno_cong_avoid(sk, ack, acked);
126		return;
127	}
128
129	/* limited by applications */
130	if (!tcp_is_cwnd_limited(sk))
131		return;
132
133	/* We do the Veno calculations only if we got enough rtt samples */
134	if (veno->cntrtt <= 2) {
135		/* We don't have enough rtt samples to do the Veno
136		 * calculation, so we'll behave like Reno.
137		 */
138		tcp_reno_cong_avoid(sk, ack, acked);
139	} else {
140		u64 target_cwnd;
141		u32 rtt;
142
143		/* We have enough rtt samples, so, using the Veno
144		 * algorithm, we determine the state of the network.
145		 */
146
147		rtt = veno->minrtt;
148
149		target_cwnd = (u64)tcp_snd_cwnd(tp) * veno->basertt;
150		target_cwnd <<= V_PARAM_SHIFT;
151		do_div(target_cwnd, rtt);
152
153		veno->diff = (tcp_snd_cwnd(tp) << V_PARAM_SHIFT) - target_cwnd;
154
155		if (tcp_in_slow_start(tp)) {
156			/* Slow start. */
157			acked = tcp_slow_start(tp, acked);
158			if (!acked)
159				goto done;
160		}
161
162		/* Congestion avoidance. */
163		if (veno->diff < beta) {
164			/* In the "non-congestive state", increase cwnd
165			 * every rtt.
166			 */
167			tcp_cong_avoid_ai(tp, tcp_snd_cwnd(tp), acked);
168		} else {
169			/* In the "congestive state", increase cwnd
170			 * every other rtt.
171			 */
172			if (tp->snd_cwnd_cnt >= tcp_snd_cwnd(tp)) {
173				if (veno->inc &&
174				    tcp_snd_cwnd(tp) < tp->snd_cwnd_clamp) {
175					tcp_snd_cwnd_set(tp, tcp_snd_cwnd(tp) + 1);
176					veno->inc = 0;
177				} else
178					veno->inc = 1;
179				tp->snd_cwnd_cnt = 0;
180			} else
181				tp->snd_cwnd_cnt += acked;
182		}
183done:
184		if (tcp_snd_cwnd(tp) < 2)
185			tcp_snd_cwnd_set(tp, 2);
186		else if (tcp_snd_cwnd(tp) > tp->snd_cwnd_clamp)
187			tcp_snd_cwnd_set(tp, tp->snd_cwnd_clamp);
188	}
189	/* Wipe the slate clean for the next rtt. */
190	/* veno->cntrtt = 0; */
191	veno->minrtt = 0x7fffffff;
192}
193
194/* Veno MD phase */
195static u32 tcp_veno_ssthresh(struct sock *sk)
196{
197	const struct tcp_sock *tp = tcp_sk(sk);
198	struct veno *veno = inet_csk_ca(sk);
199
200	if (veno->diff < beta)
201		/* in "non-congestive state", cut cwnd by 1/5 */
202		return max(tcp_snd_cwnd(tp) * 4 / 5, 2U);
203	else
204		/* in "congestive state", cut cwnd by 1/2 */
205		return max(tcp_snd_cwnd(tp) >> 1U, 2U);
206}
207
208static struct tcp_congestion_ops tcp_veno __read_mostly = {
209	.init		= tcp_veno_init,
210	.ssthresh	= tcp_veno_ssthresh,
211	.undo_cwnd	= tcp_reno_undo_cwnd,
212	.cong_avoid	= tcp_veno_cong_avoid,
213	.pkts_acked	= tcp_veno_pkts_acked,
214	.set_state	= tcp_veno_state,
215	.cwnd_event	= tcp_veno_cwnd_event,
216
217	.owner		= THIS_MODULE,
218	.name		= "veno",
219};
220
221static int __init tcp_veno_register(void)
222{
223	BUILD_BUG_ON(sizeof(struct veno) > ICSK_CA_PRIV_SIZE);
224	tcp_register_congestion_control(&tcp_veno);
225	return 0;
226}
227
228static void __exit tcp_veno_unregister(void)
229{
230	tcp_unregister_congestion_control(&tcp_veno);
231}
232
233module_init(tcp_veno_register);
234module_exit(tcp_veno_unregister);
235
236MODULE_AUTHOR("Bin Zhou, Cheng Peng Fu");
237MODULE_LICENSE("GPL");
238MODULE_DESCRIPTION("TCP Veno");
v6.13.7
  1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * TCP Veno congestion control
  4 *
  5 * This is based on the congestion detection/avoidance scheme described in
  6 *    C. P. Fu, S. C. Liew.
  7 *    "TCP Veno: TCP Enhancement for Transmission over Wireless Access Networks."
  8 *    IEEE Journal on Selected Areas in Communication,
  9 *    Feb. 2003.
 10 * 	See https://www.ie.cuhk.edu.hk/fileadmin/staff_upload/soung/Journal/J3.pdf
 11 */
 12
 13#include <linux/mm.h>
 14#include <linux/module.h>
 15#include <linux/skbuff.h>
 16#include <linux/inet_diag.h>
 17
 18#include <net/tcp.h>
 19
 20/* Default values of the Veno variables, in fixed-point representation
 21 * with V_PARAM_SHIFT bits to the right of the binary point.
 22 */
 23#define V_PARAM_SHIFT 1
 24static const int beta = 3 << V_PARAM_SHIFT;
 25
 26/* Veno variables */
 27struct veno {
 28	u8 doing_veno_now;	/* if true, do veno for this rtt */
 29	u16 cntrtt;		/* # of rtts measured within last rtt */
 30	u32 minrtt;		/* min of rtts measured within last rtt (in usec) */
 31	u32 basertt;		/* the min of all Veno rtt measurements seen (in usec) */
 32	u32 inc;		/* decide whether to increase cwnd */
 33	u32 diff;		/* calculate the diff rate */
 34};
 35
 36/* There are several situations when we must "re-start" Veno:
 37 *
 38 *  o when a connection is established
 39 *  o after an RTO
 40 *  o after fast recovery
 41 *  o when we send a packet and there is no outstanding
 42 *    unacknowledged data (restarting an idle connection)
 43 *
 44 */
 45static inline void veno_enable(struct sock *sk)
 46{
 47	struct veno *veno = inet_csk_ca(sk);
 48
 49	/* turn on Veno */
 50	veno->doing_veno_now = 1;
 51
 52	veno->minrtt = 0x7fffffff;
 53}
 54
 55static inline void veno_disable(struct sock *sk)
 56{
 57	struct veno *veno = inet_csk_ca(sk);
 58
 59	/* turn off Veno */
 60	veno->doing_veno_now = 0;
 61}
 62
 63static void tcp_veno_init(struct sock *sk)
 64{
 65	struct veno *veno = inet_csk_ca(sk);
 66
 67	veno->basertt = 0x7fffffff;
 68	veno->inc = 1;
 69	veno_enable(sk);
 70}
 71
 72/* Do rtt sampling needed for Veno. */
 73static void tcp_veno_pkts_acked(struct sock *sk,
 74				const struct ack_sample *sample)
 75{
 76	struct veno *veno = inet_csk_ca(sk);
 77	u32 vrtt;
 78
 79	if (sample->rtt_us < 0)
 80		return;
 81
 82	/* Never allow zero rtt or baseRTT */
 83	vrtt = sample->rtt_us + 1;
 84
 85	/* Filter to find propagation delay: */
 86	if (vrtt < veno->basertt)
 87		veno->basertt = vrtt;
 88
 89	/* Find the min rtt during the last rtt to find
 90	 * the current prop. delay + queuing delay:
 91	 */
 92	veno->minrtt = min(veno->minrtt, vrtt);
 93	veno->cntrtt++;
 94}
 95
 96static void tcp_veno_state(struct sock *sk, u8 ca_state)
 97{
 98	if (ca_state == TCP_CA_Open)
 99		veno_enable(sk);
100	else
101		veno_disable(sk);
102}
103
104/*
105 * If the connection is idle and we are restarting,
106 * then we don't want to do any Veno calculations
107 * until we get fresh rtt samples.  So when we
108 * restart, we reset our Veno state to a clean
109 * state. After we get acks for this flight of
110 * packets, _then_ we can make Veno calculations
111 * again.
112 */
113static void tcp_veno_cwnd_event(struct sock *sk, enum tcp_ca_event event)
114{
115	if (event == CA_EVENT_CWND_RESTART || event == CA_EVENT_TX_START)
116		tcp_veno_init(sk);
117}
118
119static void tcp_veno_cong_avoid(struct sock *sk, u32 ack, u32 acked)
120{
121	struct tcp_sock *tp = tcp_sk(sk);
122	struct veno *veno = inet_csk_ca(sk);
123
124	if (!veno->doing_veno_now) {
125		tcp_reno_cong_avoid(sk, ack, acked);
126		return;
127	}
128
129	/* limited by applications */
130	if (!tcp_is_cwnd_limited(sk))
131		return;
132
133	/* We do the Veno calculations only if we got enough rtt samples */
134	if (veno->cntrtt <= 2) {
135		/* We don't have enough rtt samples to do the Veno
136		 * calculation, so we'll behave like Reno.
137		 */
138		tcp_reno_cong_avoid(sk, ack, acked);
139	} else {
140		u64 target_cwnd;
141		u32 rtt;
142
143		/* We have enough rtt samples, so, using the Veno
144		 * algorithm, we determine the state of the network.
145		 */
146
147		rtt = veno->minrtt;
148
149		target_cwnd = (u64)tcp_snd_cwnd(tp) * veno->basertt;
150		target_cwnd <<= V_PARAM_SHIFT;
151		do_div(target_cwnd, rtt);
152
153		veno->diff = (tcp_snd_cwnd(tp) << V_PARAM_SHIFT) - target_cwnd;
154
155		if (tcp_in_slow_start(tp)) {
156			/* Slow start. */
157			acked = tcp_slow_start(tp, acked);
158			if (!acked)
159				goto done;
160		}
161
162		/* Congestion avoidance. */
163		if (veno->diff < beta) {
164			/* In the "non-congestive state", increase cwnd
165			 * every rtt.
166			 */
167			tcp_cong_avoid_ai(tp, tcp_snd_cwnd(tp), acked);
168		} else {
169			/* In the "congestive state", increase cwnd
170			 * every other rtt.
171			 */
172			if (tp->snd_cwnd_cnt >= tcp_snd_cwnd(tp)) {
173				if (veno->inc &&
174				    tcp_snd_cwnd(tp) < tp->snd_cwnd_clamp) {
175					tcp_snd_cwnd_set(tp, tcp_snd_cwnd(tp) + 1);
176					veno->inc = 0;
177				} else
178					veno->inc = 1;
179				tp->snd_cwnd_cnt = 0;
180			} else
181				tp->snd_cwnd_cnt += acked;
182		}
183done:
184		if (tcp_snd_cwnd(tp) < 2)
185			tcp_snd_cwnd_set(tp, 2);
186		else if (tcp_snd_cwnd(tp) > tp->snd_cwnd_clamp)
187			tcp_snd_cwnd_set(tp, tp->snd_cwnd_clamp);
188	}
189	/* Wipe the slate clean for the next rtt. */
190	/* veno->cntrtt = 0; */
191	veno->minrtt = 0x7fffffff;
192}
193
194/* Veno MD phase */
195static u32 tcp_veno_ssthresh(struct sock *sk)
196{
197	const struct tcp_sock *tp = tcp_sk(sk);
198	struct veno *veno = inet_csk_ca(sk);
199
200	if (veno->diff < beta)
201		/* in "non-congestive state", cut cwnd by 1/5 */
202		return max(tcp_snd_cwnd(tp) * 4 / 5, 2U);
203	else
204		/* in "congestive state", cut cwnd by 1/2 */
205		return max(tcp_snd_cwnd(tp) >> 1U, 2U);
206}
207
208static struct tcp_congestion_ops tcp_veno __read_mostly = {
209	.init		= tcp_veno_init,
210	.ssthresh	= tcp_veno_ssthresh,
211	.undo_cwnd	= tcp_reno_undo_cwnd,
212	.cong_avoid	= tcp_veno_cong_avoid,
213	.pkts_acked	= tcp_veno_pkts_acked,
214	.set_state	= tcp_veno_state,
215	.cwnd_event	= tcp_veno_cwnd_event,
216
217	.owner		= THIS_MODULE,
218	.name		= "veno",
219};
220
221static int __init tcp_veno_register(void)
222{
223	BUILD_BUG_ON(sizeof(struct veno) > ICSK_CA_PRIV_SIZE);
224	tcp_register_congestion_control(&tcp_veno);
225	return 0;
226}
227
228static void __exit tcp_veno_unregister(void)
229{
230	tcp_unregister_congestion_control(&tcp_veno);
231}
232
233module_init(tcp_veno_register);
234module_exit(tcp_veno_unregister);
235
236MODULE_AUTHOR("Bin Zhou, Cheng Peng Fu");
237MODULE_LICENSE("GPL");
238MODULE_DESCRIPTION("TCP Veno");