/*- * Copyright (c) 2009-2010 * Swinburne University of Technology, Melbourne, Australia * Copyright (c) 2010 Lawrence Stewart * Copyright (c) 2010-2011 The FreeBSD Foundation * All rights reserved. * * This software was developed at the Centre for Advanced Internet * Architectures, Swinburne University of Technology, by David Hayes and * Lawrence Stewart, made possible in part by a grant from the Cisco University * Research Program Fund at Community Foundation Silicon Valley. * * Portions of this software were developed at the Centre for Advanced Internet * Architectures, Swinburne University of Technology, Melbourne, Australia by * David Hayes under sponsorship from the FreeBSD Foundation. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. */ /* * An implementation of the Vegas congestion control algorithm for FreeBSD, * based on L. S. Brakmo and L. L. Peterson, "TCP Vegas: end to end congestion * avoidance on a global internet", IEEE J. Sel. Areas Commun., vol. 13, no. 8, * pp. 1465-1480, Oct. 1995. The original Vegas duplicate ack policy has not * been implemented, since clock ticks are not as coarse as they were (i.e. * 500ms) when Vegas was designed. Also, packets are timed once per RTT as in * the original paper. * * Originally released as part of the NewTCP research project at Swinburne * University of Technology's Centre for Advanced Internet Architectures, * Melbourne, Australia, which was made possible in part by a grant from the * Cisco University Research Program Fund at Community Foundation Silicon * Valley. More details are available at: * http://caia.swin.edu.au/urp/newtcp/ */ #include __FBSDID("$FreeBSD$"); #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #define CAST_PTR_INT(X) (*((int*)(X))) /* * Private signal type for rate based congestion signal. * See for appropriate bit-range to use for private signals. */ #define CC_VEGAS_RATE 0x01000000 static void vegas_ack_received(struct cc_var *ccv, uint16_t ack_type); static void vegas_cb_destroy(struct cc_var *ccv); static int vegas_cb_init(struct cc_var *ccv); static void vegas_cong_signal(struct cc_var *ccv, uint32_t signal_type); static void vegas_conn_init(struct cc_var *ccv); static int vegas_mod_init(void); struct vegas { int slow_start_toggle; }; static int32_t ertt_id; static VNET_DEFINE(uint32_t, vegas_alpha) = 1; static VNET_DEFINE(uint32_t, vegas_beta) = 3; #define V_vegas_alpha VNET(vegas_alpha) #define V_vegas_beta VNET(vegas_beta) static MALLOC_DEFINE(M_VEGAS, "vegas data", "Per connection data required for the Vegas congestion control algorithm"); struct cc_algo vegas_cc_algo = { .name = "vegas", .ack_received = vegas_ack_received, .cb_destroy = vegas_cb_destroy, .cb_init = vegas_cb_init, .cong_signal = vegas_cong_signal, .conn_init = vegas_conn_init, .mod_init = vegas_mod_init }; /* * The vegas window adjustment is done once every RTT, as indicated by the * ERTT_NEW_MEASUREMENT flag. This flag is reset once the new measurment data * has been used. */ static void vegas_ack_received(struct cc_var *ccv, uint16_t ack_type) { struct ertt *e_t; struct vegas *vegas_data; long actual_tx_rate, expected_tx_rate, ndiff; e_t = khelp_get_osd(CCV(ccv, osd), ertt_id); vegas_data = ccv->cc_data; if (e_t->flags & ERTT_NEW_MEASUREMENT) { /* Once per RTT. */ if (e_t->minrtt && e_t->markedpkt_rtt) { expected_tx_rate = e_t->marked_snd_cwnd / e_t->minrtt; actual_tx_rate = e_t->bytes_tx_in_marked_rtt / e_t->markedpkt_rtt; ndiff = (expected_tx_rate - actual_tx_rate) * e_t->minrtt / CCV(ccv, t_maxseg); if (ndiff < V_vegas_alpha) { if (CCV(ccv, snd_cwnd) <= CCV(ccv, snd_ssthresh)) { vegas_data->slow_start_toggle = vegas_data->slow_start_toggle ? 0 : 1; } else { vegas_data->slow_start_toggle = 0; CCV(ccv, snd_cwnd) = min(CCV(ccv, snd_cwnd) + CCV(ccv, t_maxseg), TCP_MAXWIN << CCV(ccv, snd_scale)); } } else if (ndiff > V_vegas_beta) { /* Rate-based congestion. */ vegas_cong_signal(ccv, CC_VEGAS_RATE); vegas_data->slow_start_toggle = 0; } } e_t->flags &= ~ERTT_NEW_MEASUREMENT; } if (vegas_data->slow_start_toggle) newreno_cc_algo.ack_received(ccv, ack_type); } static void vegas_cb_destroy(struct cc_var *ccv) { if (ccv->cc_data != NULL) free(ccv->cc_data, M_VEGAS); } static int vegas_cb_init(struct cc_var *ccv) { struct vegas *vegas_data; vegas_data = malloc(sizeof(struct vegas), M_VEGAS, M_NOWAIT); if (vegas_data == NULL) return (ENOMEM); vegas_data->slow_start_toggle = 1; ccv->cc_data = vegas_data; return (0); } /* * If congestion has been triggered triggered by the Vegas measured rates, it is * handled here, otherwise it falls back to newreno's congestion handling. */ static void vegas_cong_signal(struct cc_var *ccv, uint32_t signal_type) { struct vegas *vegas_data; int presignalrecov; vegas_data = ccv->cc_data; if (IN_RECOVERY(CCV(ccv, t_flags))) presignalrecov = 1; else presignalrecov = 0; switch(signal_type) { case CC_VEGAS_RATE: if (!IN_RECOVERY(CCV(ccv, t_flags))) { CCV(ccv, snd_cwnd) = max(2 * CCV(ccv, t_maxseg), CCV(ccv, snd_cwnd) - CCV(ccv, t_maxseg)); if (CCV(ccv, snd_cwnd) < CCV(ccv, snd_ssthresh)) /* Exit slow start. */ CCV(ccv, snd_ssthresh) = CCV(ccv, snd_cwnd); } break; default: newreno_cc_algo.cong_signal(ccv, signal_type); } if (IN_RECOVERY(CCV(ccv, t_flags)) && !presignalrecov) vegas_data->slow_start_toggle = (CCV(ccv, snd_cwnd) < CCV(ccv, snd_ssthresh)) ? 1 : 0; } static void vegas_conn_init(struct cc_var *ccv) { struct vegas *vegas_data; vegas_data = ccv->cc_data; vegas_data->slow_start_toggle = 1; } static int vegas_mod_init(void) { ertt_id = khelp_get_id("ertt"); if (ertt_id <= 0) { printf("%s: h_ertt module not found\n", __func__); return (ENOENT); } vegas_cc_algo.after_idle = newreno_cc_algo.after_idle; vegas_cc_algo.post_recovery = newreno_cc_algo.post_recovery; return (0); } static int vegas_alpha_handler(SYSCTL_HANDLER_ARGS) { int error; uint32_t new; new = V_vegas_alpha; error = sysctl_handle_int(oidp, &new, 0, req); if (error == 0 && req->newptr != NULL) { if (CAST_PTR_INT(req->newptr) < 1 || CAST_PTR_INT(req->newptr) > V_vegas_beta) error = EINVAL; else V_vegas_alpha = new; } return (error); } static int vegas_beta_handler(SYSCTL_HANDLER_ARGS) { int error; uint32_t new; new = V_vegas_beta; error = sysctl_handle_int(oidp, &new, 0, req); if (error == 0 && req->newptr != NULL) { if (CAST_PTR_INT(req->newptr) < 1 || CAST_PTR_INT(req->newptr) < V_vegas_alpha) error = EINVAL; else V_vegas_beta = new; } return (error); } SYSCTL_DECL(_net_inet_tcp_cc_vegas); SYSCTL_NODE(_net_inet_tcp_cc, OID_AUTO, vegas, CTLFLAG_RW, NULL, "Vegas related settings"); SYSCTL_VNET_PROC(_net_inet_tcp_cc_vegas, OID_AUTO, alpha, CTLTYPE_UINT|CTLFLAG_RW, &VNET_NAME(vegas_alpha), 1, &vegas_alpha_handler, "IU", "vegas alpha, specified as number of \"buffers\" (0 < alpha < beta)"); SYSCTL_VNET_PROC(_net_inet_tcp_cc_vegas, OID_AUTO, beta, CTLTYPE_UINT|CTLFLAG_RW, &VNET_NAME(vegas_beta), 3, &vegas_beta_handler, "IU", "vegas beta, specified as number of \"buffers\" (0 < alpha < beta)"); DECLARE_CC_MODULE(vegas, &vegas_cc_algo); MODULE_DEPEND(vegas, ertt, 1, 1, 1);