2ea8da28e9
somewhere along the way due to mismerging r211464 in our development tree. - Capture the essence of r211464 in NewReno's after_idle() hook. We don't use V_ss_fltsz/V_ss_fltsz_local yet which needs to be revisited. Sponsored by: FreeBSD Foundation Submitted by: David Hayes <dahayes at swin edu au> MFC after: 9 weeks X-MFC with: r215166
245 lines
7.8 KiB
C
245 lines
7.8 KiB
C
/*-
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* Copyright (c) 1982, 1986, 1988, 1990, 1993, 1994, 1995
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* The Regents of the University of California.
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* Copyright (c) 2007-2008,2010
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* Swinburne University of Technology, Melbourne, Australia.
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* Copyright (c) 2009-2010 Lawrence Stewart <lstewart@freebsd.org>
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* Copyright (c) 2010 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, by Lawrence Stewart, James Healy and
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* David Hayes, 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
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* Internet Architectures, Swinburne University of Technology, Melbourne,
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* Australia by 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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* This software was first released in 2007 by James Healy and Lawrence Stewart
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* whilst working on the NewTCP research project at Swinburne University's
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* Centre for Advanced Internet Architectures, Melbourne, Australia, which was
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* made possible in part by a grant from the Cisco University Research Program
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* Fund at Community Foundation Silicon 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/module.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 <net/if.h>
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#include <net/if_var.h>
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#include <netinet/cc.h>
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#include <netinet/in.h>
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#include <netinet/in_pcb.h>
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#include <netinet/tcp_seq.h>
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#include <netinet/tcp_var.h>
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#include <netinet/cc/cc_module.h>
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void newreno_ack_received(struct cc_var *ccv, uint16_t type);
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void newreno_cong_signal(struct cc_var *ccv, uint32_t type);
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void newreno_post_recovery(struct cc_var *ccv);
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void newreno_after_idle(struct cc_var *ccv);
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struct cc_algo newreno_cc_algo = {
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.name = "newreno",
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.ack_received = newreno_ack_received,
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.cong_signal = newreno_cong_signal,
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.post_recovery = newreno_post_recovery,
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.after_idle = newreno_after_idle
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};
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/*
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* Increase cwnd on receipt of a successful ACK:
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* if cwnd <= ssthresh, increases by 1 MSS per ACK
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* if cwnd > ssthresh, increase by ~1 MSS per RTT
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*/
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void
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newreno_ack_received(struct cc_var *ccv, uint16_t type)
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{
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if (type == CC_ACK && !IN_RECOVERY(CCV(ccv, t_flags)) &&
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(ccv->flags & CCF_CWND_LIMITED)) {
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u_int cw = CCV(ccv, snd_cwnd);
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u_int incr = CCV(ccv, t_maxseg);
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/*
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* Regular in-order ACK, open the congestion window.
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* Method depends on which congestion control state we're
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* in (slow start or cong avoid) and if ABC (RFC 3465) is
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* enabled.
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*
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* slow start: cwnd <= ssthresh
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* cong avoid: cwnd > ssthresh
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*
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* slow start and ABC (RFC 3465):
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* Grow cwnd exponentially by the amount of data
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* ACKed capping the max increment per ACK to
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* (abc_l_var * maxseg) bytes.
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*
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* slow start without ABC (RFC 5681):
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* Grow cwnd exponentially by maxseg per ACK.
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*
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* cong avoid and ABC (RFC 3465):
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* Grow cwnd linearly by maxseg per RTT for each
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* cwnd worth of ACKed data.
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*
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* cong avoid without ABC (RFC 5681):
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* Grow cwnd linearly by approximately maxseg per RTT using
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* maxseg^2 / cwnd per ACK as the increment.
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* If cwnd > maxseg^2, fix the cwnd increment at 1 byte to
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* avoid capping cwnd.
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*/
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if (cw > CCV(ccv, snd_ssthresh)) {
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if (V_tcp_do_rfc3465) {
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if (ccv->flags & CCF_ABC_SENTAWND)
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ccv->flags &= ~CCF_ABC_SENTAWND;
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else
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incr = 0;
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} else
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incr = max((incr * incr / cw), 1);
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} else if (V_tcp_do_rfc3465) {
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/*
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* In slow-start with ABC enabled and no RTO in sight?
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* (Must not use abc_l_var > 1 if slow starting after
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* an RTO. On RTO, snd_nxt = snd_una, so the
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* snd_nxt == snd_max check is sufficient to
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* handle this).
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*
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* XXXLAS: Find a way to signal SS after RTO that
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* doesn't rely on tcpcb vars.
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*/
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if (CCV(ccv, snd_nxt) == CCV(ccv, snd_max))
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incr = min(ccv->bytes_this_ack,
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V_tcp_abc_l_var * CCV(ccv, t_maxseg));
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else
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incr = min(ccv->bytes_this_ack, CCV(ccv, t_maxseg));
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}
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/* ABC is on by default, so incr equals 0 frequently. */
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if (incr > 0)
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CCV(ccv, snd_cwnd) = min(cw + incr,
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TCP_MAXWIN << CCV(ccv, snd_scale));
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}
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}
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/*
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* manage congestion signals
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*/
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void
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newreno_cong_signal(struct cc_var *ccv, uint32_t type)
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{
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u_int win;
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win = max(CCV(ccv, snd_cwnd) / 2 / CCV(ccv, t_maxseg), 2) *
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CCV(ccv, t_maxseg);
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switch (type) {
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case CC_NDUPACK:
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if (!IN_FASTRECOVERY(CCV(ccv, t_flags))) {
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if (!IN_CONGRECOVERY(CCV(ccv, t_flags)))
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CCV(ccv, snd_ssthresh) = win;
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ENTER_RECOVERY(CCV(ccv, t_flags));
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}
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break;
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case CC_ECN:
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if (!IN_CONGRECOVERY(CCV(ccv, t_flags))) {
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CCV(ccv, snd_ssthresh) = win;
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CCV(ccv, snd_cwnd) = win;
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ENTER_CONGRECOVERY(CCV(ccv, t_flags));
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}
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break;
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}
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}
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/*
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* decrease the cwnd in response to packet loss or a transmit timeout.
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* th can be null, in which case cwnd will be set according to reno instead
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* of new reno.
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*/
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void
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newreno_post_recovery(struct cc_var *ccv)
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{
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if (IN_FASTRECOVERY(CCV(ccv, t_flags))) {
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/*
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* Fast recovery will conclude after returning from this
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* function. Window inflation should have left us with
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* approximately snd_ssthresh outstanding data. But in case we
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* would be inclined to send a burst, better to do it via the
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* slow start mechanism.
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*
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* XXXLAS: Find a way to do this without needing curack
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*/
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if (SEQ_GT(ccv->curack + CCV(ccv, snd_ssthresh),
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CCV(ccv, snd_max)))
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CCV(ccv, snd_cwnd) = CCV(ccv, snd_max) -
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ccv->curack + CCV(ccv, t_maxseg);
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else
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CCV(ccv, snd_cwnd) = CCV(ccv, snd_ssthresh);
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}
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}
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/*
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* if a connection has been idle for a while and more data is ready to be sent,
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* reset cwnd
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*/
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void
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newreno_after_idle(struct cc_var *ccv)
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{
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int rw;
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/*
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* If we've been idle for more than one retransmit timeout the old
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* congestion window is no longer current and we have to reduce it to
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* the restart window before we can transmit again.
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*
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* The restart window is the initial window or the last CWND, whichever
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* is smaller.
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*
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* This is done to prevent us from flooding the path with a full CWND at
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* wirespeed, overloading router and switch buffers along the way.
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*
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* See RFC5681 Section 4.1. "Restarting Idle Connections".
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*/
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if (V_tcp_do_rfc3390)
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rw = min(4 * CCV(ccv, t_maxseg),
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max(2 * CCV(ccv, t_maxseg), 4380));
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else
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rw = CCV(ccv, t_maxseg) * 2;
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CCV(ccv, snd_cwnd) = min(rw, CCV(ccv, snd_cwnd));
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}
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DECLARE_CC_MODULE(newreno, &newreno_cc_algo);
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