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

     /*-
      * 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/in.h>
    #include <netinet/in_pcb.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 size_t   hd_data_sz(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,
           .cc_data_sz = hd_data_sz,
           .after_idle = newreno_cc_after_idle,
           .cong_signal = newreno_cc_cong_signal,
           .post_recovery = newreno_cc_post_recovery,
   };
   
   static size_t
   hd_data_sz(void)
   {
           return (0);
   }
   
   /*
    * 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, t_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_cong_signal(ccv,
                                               CC_ECN);
                                           return;
                                   }
                           }
                   }
           }
           newreno_cc_ack_received(ccv, ack_type);
   }
   
   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);
           }
           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_VERSION(hd, 2);
   MODULE_DEPEND(hd, ertt, 1, 1, 1);

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