2 * Copyright (c) 2009-2010
3 * Swinburne University of Technology, Melbourne, Australia
4 * Copyright (c) 2010 Lawrence Stewart <lstewart@freebsd.org>
5 * Copyright (c) 2010-2011 The FreeBSD Foundation
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.
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.
17 * Redistribution and use in source and binary forms, with or without
18 * modification, are permitted provided that the following conditions
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.
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
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
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/
56 #include <sys/cdefs.h>
57 __FBSDID("$FreeBSD$");
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>
73 #include <netinet/cc.h>
74 #include <netinet/tcp_seq.h>
75 #include <netinet/tcp_timer.h>
76 #include <netinet/tcp_var.h>
78 #include <netinet/cc/cc_module.h>
80 #include <netinet/khelp/h_ertt.h>
82 #define CAST_PTR_INT(X) (*((int*)(X)))
85 * Private signal type for rate based congestion signal.
86 * See <netinet/cc.h> for appropriate bit-range to use for private signals.
88 #define CC_VEGAS_RATE 0x01000000
90 static void vegas_ack_received(struct cc_var *ccv, uint16_t ack_type);
91 static void vegas_cb_destroy(struct cc_var *ccv);
92 static int vegas_cb_init(struct cc_var *ccv);
93 static void vegas_cong_signal(struct cc_var *ccv, uint32_t signal_type);
94 static void vegas_conn_init(struct cc_var *ccv);
95 static int vegas_mod_init(void);
98 int slow_start_toggle;
101 static int32_t ertt_id;
103 static VNET_DEFINE(uint32_t, vegas_alpha) = 1;
104 static VNET_DEFINE(uint32_t, vegas_beta) = 3;
105 #define V_vegas_alpha VNET(vegas_alpha)
106 #define V_vegas_beta VNET(vegas_beta)
108 static MALLOC_DEFINE(M_VEGAS, "vegas data",
109 "Per connection data required for the Vegas congestion control algorithm");
111 struct cc_algo vegas_cc_algo = {
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
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
127 vegas_ack_received(struct cc_var *ccv, uint16_t ack_type)
130 struct vegas *vegas_data;
131 long actual_tx_rate, expected_tx_rate, ndiff;
133 e_t = khelp_get_osd(CCV(ccv, osd), ertt_id);
134 vegas_data = ccv->cc_data;
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 /
141 ndiff = (expected_tx_rate - actual_tx_rate) *
142 e_t->minrtt / CCV(ccv, t_maxseg);
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 ?
151 vegas_data->slow_start_toggle = 0;
153 min(CCV(ccv, snd_cwnd) +
155 TCP_MAXWIN << CCV(ccv, snd_scale));
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;
163 e_t->flags &= ~ERTT_NEW_MEASUREMENT;
166 if (vegas_data->slow_start_toggle)
167 newreno_cc_algo.ack_received(ccv, ack_type);
171 vegas_cb_destroy(struct cc_var *ccv)
174 if (ccv->cc_data != NULL)
175 free(ccv->cc_data, M_VEGAS);
179 vegas_cb_init(struct cc_var *ccv)
181 struct vegas *vegas_data;
183 vegas_data = malloc(sizeof(struct vegas), M_VEGAS, M_NOWAIT);
185 if (vegas_data == NULL)
188 vegas_data->slow_start_toggle = 1;
189 ccv->cc_data = vegas_data;
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.
199 vegas_cong_signal(struct cc_var *ccv, uint32_t signal_type)
201 struct vegas *vegas_data;
204 vegas_data = ccv->cc_data;
206 if (IN_RECOVERY(CCV(ccv, t_flags)))
211 switch(signal_type) {
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);
223 newreno_cc_algo.cong_signal(ccv, signal_type);
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;
232 vegas_conn_init(struct cc_var *ccv)
234 struct vegas *vegas_data;
236 vegas_data = ccv->cc_data;
237 vegas_data->slow_start_toggle = 1;
244 ertt_id = khelp_get_id("ertt");
246 printf("%s: h_ertt module not found\n", __func__);
250 vegas_cc_algo.after_idle = newreno_cc_algo.after_idle;
251 vegas_cc_algo.post_recovery = newreno_cc_algo.post_recovery;
257 vegas_alpha_handler(SYSCTL_HANDLER_ARGS)
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)
276 vegas_beta_handler(SYSCTL_HANDLER_ARGS)
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)
294 SYSCTL_DECL(_net_inet_tcp_cc_vegas);
295 SYSCTL_NODE(_net_inet_tcp_cc, OID_AUTO, vegas, CTLFLAG_RW, NULL,
296 "Vegas related settings");
298 SYSCTL_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)");
302 SYSCTL_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)");
306 DECLARE_CC_MODULE(vegas, &vegas_cc_algo);
307 MODULE_DEPEND(vegas, ertt, 1, 1, 1);