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