/*-
* SPDX-License-Identifier: BSD-2-Clause-FreeBSD
*
* Copyright (c) 2009-2010
* Swinburne University of Technology, Melbourne, Australia
* Copyright (c) 2010 Lawrence Stewart <lstewart@freebsd.org>
* 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 Hamilton Institute's delay-based congestion control
* algorithm for FreeBSD, based on "A strategy for fair coexistence of loss and
* delay-based congestion control algorithms," by L. Budzisz, R. Stanojevic, R.
* Shorten, and F. Baker, IEEE Commun. Lett., vol. 13, no. 7, pp. 555--557, Jul.
* 2009.
*
* 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 <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/khelp.h>
#include <sys/limits.h>
#include <sys/malloc.h>
#include <sys/module.h>
#include <sys/queue.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/sysctl.h>
#include <sys/systm.h>
#include <net/vnet.h>
#include <netinet/tcp.h>
#include <netinet/tcp_seq.h>
#include <netinet/tcp_timer.h>
#include <netinet/tcp_var.h>
#include <netinet/cc/cc.h>
#include <netinet/cc/cc_module.h>
#include <netinet/khelp/h_ertt.h>
/* Largest possible number returned by random(). */
#define RANDOM_MAX INT_MAX
static void hd_ack_received(struct cc_var *ccv, uint16_t ack_type);
static int hd_mod_init(void);
static int ertt_id;
VNET_DEFINE_STATIC(uint32_t, hd_qthresh) = 20;
VNET_DEFINE_STATIC(uint32_t, hd_qmin) = 5;
VNET_DEFINE_STATIC(uint32_t, hd_pmax) = 5;
#define V_hd_qthresh VNET(hd_qthresh)
#define V_hd_qmin VNET(hd_qmin)
#define V_hd_pmax VNET(hd_pmax)
struct cc_algo hd_cc_algo = {
.name = "hd",
.ack_received = hd_ack_received,
.mod_init = hd_mod_init
};
/*
* Hamilton backoff function. Returns 1 if we should backoff or 0 otherwise.
*/
static __inline int
should_backoff(int qdly, int maxqdly)
{
unsigned long p;
if (qdly < V_hd_qthresh) {
p = (((RANDOM_MAX / 100) * V_hd_pmax) /
(V_hd_qthresh - V_hd_qmin)) * (qdly - V_hd_qmin);
} else {
if (qdly > V_hd_qthresh)
p = (((RANDOM_MAX / 100) * V_hd_pmax) /
(maxqdly - V_hd_qthresh)) * (maxqdly - qdly);
else
p = (RANDOM_MAX / 100) * V_hd_pmax;
}
return (random() < p);
}
/*
* If the ack type is CC_ACK, and the inferred queueing delay is greater than
* the Qmin threshold, cwnd is reduced probabilistically. When backing off due
* to delay, HD behaves like NewReno when an ECN signal is received. HD behaves
* as NewReno in all other circumstances.
*/
static void
hd_ack_received(struct cc_var *ccv, uint16_t ack_type)
{
struct ertt *e_t;
int qdly;
if (ack_type == CC_ACK) {
e_t = khelp_get_osd(CCV(ccv, osd), ertt_id);
if (e_t->rtt && e_t->minrtt && V_hd_qthresh > 0) {
qdly = e_t->rtt - e_t->minrtt;
if (qdly > V_hd_qmin &&
!IN_RECOVERY(CCV(ccv, t_flags))) {
/* Probabilistic backoff of cwnd. */
if (should_backoff(qdly,
e_t->maxrtt - e_t->minrtt)) {
/*
* Update cwnd and ssthresh update to
* half cwnd and behave like an ECN (ie
* not a packet loss).
*/
newreno_cc_algo.cong_signal(ccv,
CC_ECN);
return;
}
}
}
}
newreno_cc_algo.ack_received(ccv, ack_type); /* As for NewReno. */
}
static int
hd_mod_init(void)
{
ertt_id = khelp_get_id("ertt");
if (ertt_id <= 0) {
printf("%s: h_ertt module not found\n", __func__);
return (ENOENT);
}
hd_cc_algo.after_idle = newreno_cc_algo.after_idle;
hd_cc_algo.cong_signal = newreno_cc_algo.cong_signal;
hd_cc_algo.post_recovery = newreno_cc_algo.post_recovery;
return (0);
}
static int
hd_pmax_handler(SYSCTL_HANDLER_ARGS)
{
int error;
uint32_t new;
new = V_hd_pmax;
error = sysctl_handle_int(oidp, &new, 0, req);
if (error == 0 && req->newptr != NULL) {
if (new == 0 || new > 100)
error = EINVAL;
else
V_hd_pmax = new;
}
return (error);
}
static int
hd_qmin_handler(SYSCTL_HANDLER_ARGS)
{
int error;
uint32_t new;
new = V_hd_qmin;
error = sysctl_handle_int(oidp, &new, 0, req);
if (error == 0 && req->newptr != NULL) {
if (new > V_hd_qthresh)
error = EINVAL;
else
V_hd_qmin = new;
}
return (error);
}
static int
hd_qthresh_handler(SYSCTL_HANDLER_ARGS)
{
int error;
uint32_t new;
new = V_hd_qthresh;
error = sysctl_handle_int(oidp, &new, 0, req);
if (error == 0 && req->newptr != NULL) {
if (new == 0 || new < V_hd_qmin)
error = EINVAL;
else
V_hd_qthresh = new;
}
return (error);
}
SYSCTL_DECL(_net_inet_tcp_cc_hd);
SYSCTL_NODE(_net_inet_tcp_cc, OID_AUTO, hd, CTLFLAG_RW | CTLFLAG_MPSAFE, NULL,
"Hamilton delay-based congestion control related settings");
SYSCTL_PROC(_net_inet_tcp_cc_hd, OID_AUTO, queue_threshold,
CTLFLAG_VNET | CTLTYPE_UINT | CTLFLAG_RW | CTLFLAG_NEEDGIANT,
&VNET_NAME(hd_qthresh), 20, &hd_qthresh_handler, "IU",
"queueing congestion threshold (qth) in ticks");
SYSCTL_PROC(_net_inet_tcp_cc_hd, OID_AUTO, pmax,
CTLFLAG_VNET | CTLTYPE_UINT | CTLFLAG_RW | CTLFLAG_NEEDGIANT,
&VNET_NAME(hd_pmax), 5, &hd_pmax_handler, "IU",
"per packet maximum backoff probability as a percentage");
SYSCTL_PROC(_net_inet_tcp_cc_hd, OID_AUTO, queue_min,
CTLFLAG_VNET | CTLTYPE_UINT | CTLFLAG_RW | CTLFLAG_NEEDGIANT,
&VNET_NAME(hd_qmin), 5, &hd_qmin_handler, "IU",
"minimum queueing delay threshold (qmin) in ticks");
DECLARE_CC_MODULE(hd, &hd_cc_algo);
MODULE_DEPEND(hd, ertt, 1, 1, 1);
