cc_hd.c

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    1 /*-
    2  * Copyright (c) 2009-2010
    3  *      Swinburne University of Technology, Melbourne, Australia
    4  * Copyright (c) 2010 Lawrence Stewart <lstewart@freebsd.org>
    5  * Copyright (c) 2010-2011 The FreeBSD Foundation
    6  * All rights reserved.
    7  *
    8  * This software was developed at the Centre for Advanced Internet
    9  * Architectures, Swinburne University of Technology, by David Hayes and
   10  * Lawrence Stewart, made possible in part by a grant from the Cisco University
   11  * Research Program Fund at Community Foundation Silicon Valley.
   12  *
   13  * Portions of this software were developed at the Centre for Advanced Internet
   14  * Architectures, Swinburne University of Technology, Melbourne, Australia by
   15  * David Hayes under sponsorship from the FreeBSD Foundation.
   16  *
   17  * Redistribution and use in source and binary forms, with or without
   18  * modification, are permitted provided that the following conditions
   19  * are met:
   20  * 1. Redistributions of source code must retain the above copyright
   21  *    notice, this list of conditions and the following disclaimer.
   22  * 2. Redistributions in binary form must reproduce the above copyright
   23  *    notice, this list of conditions and the following disclaimer in the
   24  *    documentation and/or other materials provided with the distribution.
   25  *
   26  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   27  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   28  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   29  * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   30  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   31  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   32  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   33  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   34  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   35  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   36  * SUCH DAMAGE.
   37  */
   38 
   39 /*
   40  * An implementation of the Hamilton Institute's delay-based congestion control
   41  * algorithm for FreeBSD, based on "A strategy for fair coexistence of loss and
   42  * delay-based congestion control algorithms," by L. Budzisz, R. Stanojevic, R.
   43  * Shorten, and F. Baker, IEEE Commun. Lett., vol. 13, no. 7, pp. 555--557, Jul.
   44  * 2009.
   45  *
   46  * Originally released as part of the NewTCP research project at Swinburne
   47  * University of Technology's Centre for Advanced Internet Architectures,
   48  * Melbourne, Australia, which was made possible in part by a grant from the
   49  * Cisco University Research Program Fund at Community Foundation Silicon
   50  * Valley. More details are available at:
   51  *   http://caia.swin.edu.au/urp/newtcp/
   52  */
   53 
   54 #include <sys/cdefs.h>
   55 __FBSDID("$FreeBSD: releng/10.3/sys/netinet/cc/cc_hd.c 220560 2011-04-12 08:13:18Z lstewart $");
   56 
   57 #include <sys/param.h>
   58 #include <sys/kernel.h>
   59 #include <sys/khelp.h>
   60 #include <sys/limits.h>
   61 #include <sys/malloc.h>
   62 #include <sys/module.h>
   63 #include <sys/queue.h>
   64 #include <sys/socket.h>
   65 #include <sys/socketvar.h>
   66 #include <sys/sysctl.h>
   67 #include <sys/systm.h>
   68 
   69 #include <net/if.h>
   70 #include <net/vnet.h>
   71 
   72 #include <netinet/cc.h>
   73 #include <netinet/tcp_seq.h>
   74 #include <netinet/tcp_timer.h>
   75 #include <netinet/tcp_var.h>
   76 
   77 #include <netinet/cc/cc_module.h>
   78 
   79 #include <netinet/khelp/h_ertt.h>
   80 
   81 #define CAST_PTR_INT(X) (*((int*)(X)))
   82 
   83 /* Largest possible number returned by random(). */
   84 #define RANDOM_MAX      INT_MAX
   85 
   86 static void     hd_ack_received(struct cc_var *ccv, uint16_t ack_type);
   87 static int      hd_mod_init(void);
   88 
   89 static int ertt_id;
   90 
   91 static VNET_DEFINE(uint32_t, hd_qthresh) = 20;
   92 static VNET_DEFINE(uint32_t, hd_qmin) = 5;
   93 static VNET_DEFINE(uint32_t, hd_pmax) = 5;
   94 #define V_hd_qthresh    VNET(hd_qthresh)
   95 #define V_hd_qmin       VNET(hd_qmin)
   96 #define V_hd_pmax       VNET(hd_pmax)
   97 
   98 struct cc_algo hd_cc_algo = {
   99         .name = "hd",
  100         .ack_received = hd_ack_received,
  101         .mod_init = hd_mod_init
  102 };
  103 
  104 /*
  105  * Hamilton backoff function. Returns 1 if we should backoff or 0 otherwise.
  106  */
  107 static __inline int
  108 should_backoff(int qdly, int maxqdly)
  109 {
  110         unsigned long p;
  111 
  112         if (qdly < V_hd_qthresh) {
  113                 p = (((RANDOM_MAX / 100) * V_hd_pmax) /
  114                     (V_hd_qthresh - V_hd_qmin)) * (qdly - V_hd_qmin);
  115         } else {
  116                 if (qdly > V_hd_qthresh)
  117                         p = (((RANDOM_MAX / 100) * V_hd_pmax) /
  118                             (maxqdly - V_hd_qthresh)) * (maxqdly - qdly);
  119                 else
  120                         p = (RANDOM_MAX / 100) * V_hd_pmax;
  121         }
  122 
  123         return (random() < p);
  124 }
  125 
  126 /*
  127  * If the ack type is CC_ACK, and the inferred queueing delay is greater than
  128  * the Qmin threshold, cwnd is reduced probabilistically. When backing off due
  129  * to delay, HD behaves like NewReno when an ECN signal is received. HD behaves
  130  * as NewReno in all other circumstances.
  131  */
  132 static void
  133 hd_ack_received(struct cc_var *ccv, uint16_t ack_type)
  134 {
  135         struct ertt *e_t;
  136         int qdly;
  137 
  138         if (ack_type == CC_ACK) {
  139                 e_t = khelp_get_osd(CCV(ccv, osd), ertt_id);
  140 
  141                 if (e_t->rtt && e_t->minrtt && V_hd_qthresh > 0) {
  142                         qdly = e_t->rtt - e_t->minrtt;
  143 
  144                         if (qdly > V_hd_qmin &&
  145                             !IN_RECOVERY(CCV(ccv, t_flags))) {
  146                                 /* Probabilistic backoff of cwnd. */
  147                                 if (should_backoff(qdly,
  148                                     e_t->maxrtt - e_t->minrtt)) {
  149                                         /*
  150                                          * Update cwnd and ssthresh update to
  151                                          * half cwnd and behave like an ECN (ie
  152                                          * not a packet loss).
  153                                          */
  154                                         newreno_cc_algo.cong_signal(ccv,
  155                                             CC_ECN);
  156                                         return;
  157                                 }
  158                         }
  159                 }
  160         }
  161         newreno_cc_algo.ack_received(ccv, ack_type); /* As for NewReno. */
  162 }
  163 
  164 static int
  165 hd_mod_init(void)
  166 {
  167 
  168         ertt_id = khelp_get_id("ertt");
  169         if (ertt_id <= 0) {
  170                 printf("%s: h_ertt module not found\n", __func__);
  171                 return (ENOENT);
  172         }
  173 
  174         hd_cc_algo.after_idle = newreno_cc_algo.after_idle;
  175         hd_cc_algo.cong_signal = newreno_cc_algo.cong_signal;
  176         hd_cc_algo.post_recovery = newreno_cc_algo.post_recovery;
  177 
  178         return (0);
  179 }
  180 
  181 static int
  182 hd_pmax_handler(SYSCTL_HANDLER_ARGS)
  183 {
  184         int error;
  185         uint32_t new;
  186 
  187         new = V_hd_pmax;
  188         error = sysctl_handle_int(oidp, &new, 0, req);
  189         if (error == 0 && req->newptr != NULL) {
  190                 if (CAST_PTR_INT(req->newptr) == 0 ||
  191                     CAST_PTR_INT(req->newptr) > 100)
  192                         error = EINVAL;
  193                 else
  194                         V_hd_pmax = new;
  195         }
  196 
  197         return (error);
  198 }
  199 
  200 static int
  201 hd_qmin_handler(SYSCTL_HANDLER_ARGS)
  202 {
  203         int error;
  204         uint32_t new;
  205 
  206         new = V_hd_qmin;
  207         error = sysctl_handle_int(oidp, &new, 0, req);
  208         if (error == 0 && req->newptr != NULL) {
  209                 if (CAST_PTR_INT(req->newptr) > V_hd_qthresh)
  210                         error = EINVAL;
  211                 else
  212                         V_hd_qmin = new;
  213         }
  214 
  215         return (error);
  216 }
  217 
  218 static int
  219 hd_qthresh_handler(SYSCTL_HANDLER_ARGS)
  220 {
  221         int error;
  222         uint32_t new;
  223 
  224         new = V_hd_qthresh;
  225         error = sysctl_handle_int(oidp, &new, 0, req);
  226         if (error == 0 && req->newptr != NULL) {
  227                 if (CAST_PTR_INT(req->newptr) < 1 ||
  228                     CAST_PTR_INT(req->newptr) < V_hd_qmin)
  229                         error = EINVAL;
  230                 else
  231                         V_hd_qthresh = new;
  232         }
  233 
  234         return (error);
  235 }
  236 
  237 SYSCTL_DECL(_net_inet_tcp_cc_hd);
  238 SYSCTL_NODE(_net_inet_tcp_cc, OID_AUTO, hd, CTLFLAG_RW, NULL,
  239     "Hamilton delay-based congestion control related settings");
  240 
  241 SYSCTL_VNET_PROC(_net_inet_tcp_cc_hd, OID_AUTO, queue_threshold,
  242     CTLTYPE_UINT|CTLFLAG_RW, &VNET_NAME(hd_qthresh), 20, &hd_qthresh_handler,
  243     "IU", "queueing congestion threshold (qth) in ticks");
  244 
  245 SYSCTL_VNET_PROC(_net_inet_tcp_cc_hd, OID_AUTO, pmax,
  246     CTLTYPE_UINT|CTLFLAG_RW, &VNET_NAME(hd_pmax), 5, &hd_pmax_handler,
  247     "IU", "per packet maximum backoff probability as a percentage");
  248 
  249 SYSCTL_VNET_PROC(_net_inet_tcp_cc_hd, OID_AUTO, queue_min,
  250     CTLTYPE_UINT|CTLFLAG_RW, &VNET_NAME(hd_qmin), 5, &hd_qmin_handler,
  251     "IU", "minimum queueing delay threshold (qmin) in ticks");
  252 
  253 DECLARE_CC_MODULE(hd, &hd_cc_algo);
  254 MODULE_DEPEND(hd, ertt, 1, 1, 1);

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FreeBSD/Linux Kernel Cross Reference sys/netinet/cc/cc_hd.c

FreeBSD/Linux Kernel Cross Reference
sys/netinet/cc/cc_hd.c