99f4ec50e8
Sponsored by: Nginx, Inc.
256 lines
7.4 KiB
C
256 lines
7.4 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 Hamilton Institute's delay-based congestion control
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* algorithm for FreeBSD, based on "A strategy for fair coexistence of loss and
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* delay-based congestion control algorithms," by L. Budzisz, R. Stanojevic, R.
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* Shorten, and F. Baker, IEEE Commun. Lett., vol. 13, no. 7, pp. 555--557, Jul.
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* 2009.
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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/limits.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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/* Largest possible number returned by random(). */
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#define RANDOM_MAX INT_MAX
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static void hd_ack_received(struct cc_var *ccv, uint16_t ack_type);
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static int hd_mod_init(void);
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static int ertt_id;
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static VNET_DEFINE(uint32_t, hd_qthresh) = 20;
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static VNET_DEFINE(uint32_t, hd_qmin) = 5;
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static VNET_DEFINE(uint32_t, hd_pmax) = 5;
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#define V_hd_qthresh VNET(hd_qthresh)
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#define V_hd_qmin VNET(hd_qmin)
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#define V_hd_pmax VNET(hd_pmax)
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struct cc_algo hd_cc_algo = {
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.name = "hd",
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.ack_received = hd_ack_received,
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.mod_init = hd_mod_init
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};
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/*
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* Hamilton backoff function. Returns 1 if we should backoff or 0 otherwise.
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*/
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static __inline int
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should_backoff(int qdly, int maxqdly)
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{
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unsigned long p;
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if (qdly < V_hd_qthresh) {
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p = (((RANDOM_MAX / 100) * V_hd_pmax) /
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(V_hd_qthresh - V_hd_qmin)) * (qdly - V_hd_qmin);
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} else {
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if (qdly > V_hd_qthresh)
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p = (((RANDOM_MAX / 100) * V_hd_pmax) /
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(maxqdly - V_hd_qthresh)) * (maxqdly - qdly);
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else
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p = (RANDOM_MAX / 100) * V_hd_pmax;
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}
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return (random() < p);
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}
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/*
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* If the ack type is CC_ACK, and the inferred queueing delay is greater than
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* the Qmin threshold, cwnd is reduced probabilistically. When backing off due
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* to delay, HD behaves like NewReno when an ECN signal is received. HD behaves
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* as NewReno in all other circumstances.
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*/
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static void
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hd_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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int qdly;
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if (ack_type == CC_ACK) {
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e_t = khelp_get_osd(CCV(ccv, osd), ertt_id);
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if (e_t->rtt && e_t->minrtt && V_hd_qthresh > 0) {
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qdly = e_t->rtt - e_t->minrtt;
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if (qdly > V_hd_qmin &&
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!IN_RECOVERY(CCV(ccv, t_flags))) {
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/* Probabilistic backoff of cwnd. */
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if (should_backoff(qdly,
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e_t->maxrtt - e_t->minrtt)) {
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/*
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* Update cwnd and ssthresh update to
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* half cwnd and behave like an ECN (ie
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* not a packet loss).
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*/
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newreno_cc_algo.cong_signal(ccv,
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CC_ECN);
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return;
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}
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}
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}
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}
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newreno_cc_algo.ack_received(ccv, ack_type); /* As for NewReno. */
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}
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static int
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hd_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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hd_cc_algo.after_idle = newreno_cc_algo.after_idle;
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hd_cc_algo.cong_signal = newreno_cc_algo.cong_signal;
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hd_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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hd_pmax_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_hd_pmax;
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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) == 0 ||
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CAST_PTR_INT(req->newptr) > 100)
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error = EINVAL;
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else
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V_hd_pmax = 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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hd_qmin_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_hd_qmin;
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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) > V_hd_qthresh)
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error = EINVAL;
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else
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V_hd_qmin = 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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hd_qthresh_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_hd_qthresh;
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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_hd_qmin)
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error = EINVAL;
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else
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V_hd_qthresh = 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_hd);
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SYSCTL_NODE(_net_inet_tcp_cc, OID_AUTO, hd, CTLFLAG_RW, NULL,
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"Hamilton delay-based congestion control related settings");
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SYSCTL_PROC(_net_inet_tcp_cc_hd, OID_AUTO, queue_threshold,
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CTLFLAG_VNET | CTLTYPE_UINT | CTLFLAG_RW, &VNET_NAME(hd_qthresh), 20,
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&hd_qthresh_handler, "IU", "queueing congestion threshold (qth) in ticks");
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SYSCTL_PROC(_net_inet_tcp_cc_hd, OID_AUTO, pmax,
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CTLFLAG_VNET | CTLTYPE_UINT | CTLFLAG_RW, &VNET_NAME(hd_pmax), 5,
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&hd_pmax_handler, "IU",
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"per packet maximum backoff probability as a percentage");
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SYSCTL_PROC(_net_inet_tcp_cc_hd, OID_AUTO, queue_min,
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CTLFLAG_VNET | CTLTYPE_UINT | CTLFLAG_RW, &VNET_NAME(hd_qmin), 5,
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&hd_qmin_handler, "IU", "minimum queueing delay threshold (qmin) in ticks");
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DECLARE_CC_MODULE(hd, &hd_cc_algo);
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MODULE_DEPEND(hd, ertt, 1, 1, 1);
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