1116864Speter/*-
2125537Sru * Copyright (c) 2009-2010
3125537Sru *	Swinburne University of Technology, Melbourne, Australia
4 * Copyright (c) 2010 Lawrence Stewart <lstewart@freebsd.org>
5 * Copyright (c) 2010-2011 The FreeBSD Foundation
6 * All rights reserved.
7 *
8 * This software was developed at the Centre for Advanced Internet
9 * Architectures, Swinburne University of Technology, by David Hayes and
10 * Lawrence Stewart, made possible in part by a grant from the Cisco University
11 * Research Program Fund at Community Foundation Silicon Valley.
12 *
13 * Portions of this software were developed at the Centre for Advanced Internet
14 * Architectures, Swinburne University of Technology, Melbourne, Australia by
15 * David Hayes under sponsorship from the FreeBSD Foundation.
16 *
17 * Redistribution and use in source and binary forms, with or without
18 * modification, are permitted provided that the following conditions
19 * are met:
20 * 1. Redistributions of source code must retain the above copyright
21 *    notice, this list of conditions and the following disclaimer.
22 * 2. Redistributions in binary form must reproduce the above copyright
23 *    notice, this list of conditions and the following disclaimer in the
24 *    documentation and/or other materials provided with the distribution.
25 *
26 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
27 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
28 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
29 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
30 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
31 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
32 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
33 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
34 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
35 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
36 * SUCH DAMAGE.
37 */
38
39/*
40 * An implementation of the Vegas congestion control algorithm for FreeBSD,
41 * based on L. S. Brakmo and L. L. Peterson, "TCP Vegas: end to end congestion
42 * avoidance on a global internet", IEEE J. Sel. Areas Commun., vol. 13, no. 8,
43 * pp. 1465-1480, Oct. 1995. The original Vegas duplicate ack policy has not
44 * been implemented, since clock ticks are not as coarse as they were (i.e.
45 * 500ms) when Vegas was designed. Also, packets are timed once per RTT as in
46 * the original paper.
47 *
48 * Originally released as part of the NewTCP research project at Swinburne
49 * University of Technology's Centre for Advanced Internet Architectures,
50 * Melbourne, Australia, which was made possible in part by a grant from the
51 * Cisco University Research Program Fund at Community Foundation Silicon
52 * Valley. More details are available at:
53 *   http://caia.swin.edu.au/urp/newtcp/
54 */
55
56#include <sys/cdefs.h>
57__FBSDID("$FreeBSD: releng/10.3/sys/netinet/cc/cc_vegas.c 220592 2011-04-13 11:28:46Z pluknet $");
58
59#include <sys/param.h>
60#include <sys/kernel.h>
61#include <sys/khelp.h>
62#include <sys/malloc.h>
63#include <sys/module.h>
64#include <sys/queue.h>
65#include <sys/socket.h>
66#include <sys/socketvar.h>
67#include <sys/sysctl.h>
68#include <sys/systm.h>
69
70#include <net/if.h>
71#include <net/vnet.h>
72
73#include <netinet/cc.h>
74#include <netinet/tcp_seq.h>
75#include <netinet/tcp_timer.h>
76#include <netinet/tcp_var.h>
77
78#include <netinet/cc/cc_module.h>
79
80#include <netinet/khelp/h_ertt.h>
81
82#define	CAST_PTR_INT(X)	(*((int*)(X)))
83
84/*
85 * Private signal type for rate based congestion signal.
86 * See <netinet/cc.h> for appropriate bit-range to use for private signals.
87 */
88#define	CC_VEGAS_RATE	0x01000000
89
90static void	vegas_ack_received(struct cc_var *ccv, uint16_t ack_type);
91static void	vegas_cb_destroy(struct cc_var *ccv);
92static int	vegas_cb_init(struct cc_var *ccv);
93static void	vegas_cong_signal(struct cc_var *ccv, uint32_t signal_type);
94static void	vegas_conn_init(struct cc_var *ccv);
95static int	vegas_mod_init(void);
96
97struct vegas {
98	int slow_start_toggle;
99};
100
101static int32_t ertt_id;
102
103static VNET_DEFINE(uint32_t, vegas_alpha) = 1;
104static VNET_DEFINE(uint32_t, vegas_beta) = 3;
105#define	V_vegas_alpha	VNET(vegas_alpha)
106#define	V_vegas_beta	VNET(vegas_beta)
107
108static MALLOC_DEFINE(M_VEGAS, "vegas data",
109    "Per connection data required for the Vegas congestion control algorithm");
110
111struct cc_algo vegas_cc_algo = {
112	.name = "vegas",
113	.ack_received = vegas_ack_received,
114	.cb_destroy = vegas_cb_destroy,
115	.cb_init = vegas_cb_init,
116	.cong_signal = vegas_cong_signal,
117	.conn_init = vegas_conn_init,
118	.mod_init = vegas_mod_init
119};
120
121/*
122 * The vegas window adjustment is done once every RTT, as indicated by the
123 * ERTT_NEW_MEASUREMENT flag. This flag is reset once the new measurment data
124 * has been used.
125 */
126static void
127vegas_ack_received(struct cc_var *ccv, uint16_t ack_type)
128{
129	struct ertt *e_t;
130	struct vegas *vegas_data;
131	long actual_tx_rate, expected_tx_rate, ndiff;
132
133	e_t = khelp_get_osd(CCV(ccv, osd), ertt_id);
134	vegas_data = ccv->cc_data;
135
136	if (e_t->flags & ERTT_NEW_MEASUREMENT) { /* Once per RTT. */
137		if (e_t->minrtt && e_t->markedpkt_rtt) {
138			expected_tx_rate = e_t->marked_snd_cwnd / e_t->minrtt;
139			actual_tx_rate = e_t->bytes_tx_in_marked_rtt /
140			    e_t->markedpkt_rtt;
141			ndiff = (expected_tx_rate - actual_tx_rate) *
142			    e_t->minrtt / CCV(ccv, t_maxseg);
143
144			if (ndiff < V_vegas_alpha) {
145				if (CCV(ccv, snd_cwnd) <=
146				    CCV(ccv, snd_ssthresh)) {
147					vegas_data->slow_start_toggle =
148					    vegas_data->slow_start_toggle ?
149					    0 : 1;
150				} else {
151					vegas_data->slow_start_toggle = 0;
152					CCV(ccv, snd_cwnd) =
153					    min(CCV(ccv, snd_cwnd) +
154					    CCV(ccv, t_maxseg),
155					    TCP_MAXWIN << CCV(ccv, snd_scale));
156				}
157			} else if (ndiff > V_vegas_beta) {
158				/* Rate-based congestion. */
159				vegas_cong_signal(ccv, CC_VEGAS_RATE);
160				vegas_data->slow_start_toggle = 0;
161			}
162		}
163		e_t->flags &= ~ERTT_NEW_MEASUREMENT;
164	}
165
166	if (vegas_data->slow_start_toggle)
167		newreno_cc_algo.ack_received(ccv, ack_type);
168}
169
170static void
171vegas_cb_destroy(struct cc_var *ccv)
172{
173
174	if (ccv->cc_data != NULL)
175		free(ccv->cc_data, M_VEGAS);
176}
177
178static int
179vegas_cb_init(struct cc_var *ccv)
180{
181	struct vegas *vegas_data;
182
183	vegas_data = malloc(sizeof(struct vegas), M_VEGAS, M_NOWAIT);
184
185	if (vegas_data == NULL)
186		return (ENOMEM);
187
188	vegas_data->slow_start_toggle = 1;
189	ccv->cc_data = vegas_data;
190
191	return (0);
192}
193
194/*
195 * If congestion has been triggered triggered by the Vegas measured rates, it is
196 * handled here, otherwise it falls back to newreno's congestion handling.
197 */
198static void
199vegas_cong_signal(struct cc_var *ccv, uint32_t signal_type)
200{
201	struct vegas *vegas_data;
202	int presignalrecov;
203
204	vegas_data = ccv->cc_data;
205
206	if (IN_RECOVERY(CCV(ccv, t_flags)))
207		presignalrecov = 1;
208	else
209		presignalrecov = 0;
210
211	switch(signal_type) {
212	case CC_VEGAS_RATE:
213		if (!IN_RECOVERY(CCV(ccv, t_flags))) {
214			CCV(ccv, snd_cwnd) = max(2 * CCV(ccv, t_maxseg),
215			    CCV(ccv, snd_cwnd) - CCV(ccv, t_maxseg));
216			if (CCV(ccv, snd_cwnd) < CCV(ccv, snd_ssthresh))
217				/* Exit slow start. */
218				CCV(ccv, snd_ssthresh) = CCV(ccv, snd_cwnd);
219		}
220		break;
221
222	default:
223		newreno_cc_algo.cong_signal(ccv, signal_type);
224	}
225
226	if (IN_RECOVERY(CCV(ccv, t_flags)) && !presignalrecov)
227		vegas_data->slow_start_toggle =
228		    (CCV(ccv, snd_cwnd) < CCV(ccv, snd_ssthresh)) ? 1 : 0;
229}
230
231static void
232vegas_conn_init(struct cc_var *ccv)
233{
234	struct vegas *vegas_data;
235
236	vegas_data = ccv->cc_data;
237	vegas_data->slow_start_toggle = 1;
238}
239
240static int
241vegas_mod_init(void)
242{
243
244	ertt_id = khelp_get_id("ertt");
245	if (ertt_id <= 0) {
246		printf("%s: h_ertt module not found\n", __func__);
247		return (ENOENT);
248	}
249
250	vegas_cc_algo.after_idle = newreno_cc_algo.after_idle;
251	vegas_cc_algo.post_recovery = newreno_cc_algo.post_recovery;
252
253	return (0);
254}
255
256static int
257vegas_alpha_handler(SYSCTL_HANDLER_ARGS)
258{
259	int error;
260	uint32_t new;
261
262	new = V_vegas_alpha;
263	error = sysctl_handle_int(oidp, &new, 0, req);
264	if (error == 0 && req->newptr != NULL) {
265		if (CAST_PTR_INT(req->newptr) < 1 ||
266		    CAST_PTR_INT(req->newptr) > V_vegas_beta)
267			error = EINVAL;
268		else
269			V_vegas_alpha = new;
270	}
271
272	return (error);
273}
274
275static int
276vegas_beta_handler(SYSCTL_HANDLER_ARGS)
277{
278	int error;
279	uint32_t new;
280
281	new = V_vegas_beta;
282	error = sysctl_handle_int(oidp, &new, 0, req);
283	if (error == 0 && req->newptr != NULL) {
284		if (CAST_PTR_INT(req->newptr) < 1 ||
285		    CAST_PTR_INT(req->newptr) < V_vegas_alpha)
286			 error = EINVAL;
287		else
288			V_vegas_beta = new;
289	}
290
291	return (error);
292}
293
294SYSCTL_DECL(_net_inet_tcp_cc_vegas);
295SYSCTL_NODE(_net_inet_tcp_cc, OID_AUTO, vegas, CTLFLAG_RW, NULL,
296    "Vegas related settings");
297
298SYSCTL_VNET_PROC(_net_inet_tcp_cc_vegas, OID_AUTO, alpha,
299    CTLTYPE_UINT|CTLFLAG_RW, &VNET_NAME(vegas_alpha), 1, &vegas_alpha_handler,
300    "IU", "vegas alpha, specified as number of \"buffers\" (0 < alpha < beta)");
301
302SYSCTL_VNET_PROC(_net_inet_tcp_cc_vegas, OID_AUTO, beta,
303    CTLTYPE_UINT|CTLFLAG_RW, &VNET_NAME(vegas_beta), 3, &vegas_beta_handler,
304    "IU", "vegas beta, specified as number of \"buffers\" (0 < alpha < beta)");
305
306DECLARE_CC_MODULE(vegas, &vegas_cc_algo);
307MODULE_DEPEND(vegas, ertt, 1, 1, 1);
308