The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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FreeBSD/Linux Kernel Cross Reference
sys/net80211/ieee80211_rssadapt.c

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    1 /*      $FreeBSD: stable/10/sys/net80211/ieee80211_rssadapt.c 343036 2019-01-15 02:26:03Z avos $        */
    2 /* $NetBSD: ieee80211_rssadapt.c,v 1.9 2005/02/26 22:45:09 perry Exp $ */
    3 /*-
    4  * Copyright (c) 2010 Rui Paulo <rpaulo@FreeBSD.org>
    5  * Copyright (c) 2003, 2004 David Young.  All rights reserved.
    6  *
    7  * Redistribution and use in source and binary forms, with or
    8  * without modification, are permitted provided that the following
    9  * conditions are met:
   10  * 1. Redistributions of source code must retain the above copyright
   11  *    notice, this list of conditions and the following disclaimer.
   12  * 2. Redistributions in binary form must reproduce the above
   13  *    copyright notice, this list of conditions and the following
   14  *    disclaimer in the documentation and/or other materials provided
   15  *    with the distribution.
   16  * 3. The name of David Young may not be used to endorse or promote
   17  *    products derived from this software without specific prior
   18  *    written permission.
   19  *
   20  * THIS SOFTWARE IS PROVIDED BY David Young ``AS IS'' AND ANY
   21  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
   22  * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
   23  * PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL David
   24  * Young BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
   25  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
   26  * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
   27  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
   28  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
   29  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
   31  * OF SUCH DAMAGE.
   32  */
   33 #include "opt_wlan.h"
   34 
   35 #include <sys/param.h>
   36 #include <sys/kernel.h>
   37 #include <sys/module.h>
   38 #include <sys/socket.h>
   39 #include <sys/sysctl.h>
   40 
   41 #include <net/if.h>
   42 #include <net/if_media.h>
   43 
   44 #include <net80211/ieee80211_var.h>
   45 #include <net80211/ieee80211_rssadapt.h>
   46 #include <net80211/ieee80211_ratectl.h>
   47 
   48 struct rssadapt_expavgctl {
   49         /* RSS threshold decay. */
   50         u_int rc_decay_denom;
   51         u_int rc_decay_old;
   52         /* RSS threshold update. */
   53         u_int rc_thresh_denom;
   54         u_int rc_thresh_old;
   55         /* RSS average update. */
   56         u_int rc_avgrssi_denom;
   57         u_int rc_avgrssi_old;
   58 };
   59 
   60 static struct rssadapt_expavgctl master_expavgctl = {
   61         .rc_decay_denom = 16,
   62         .rc_decay_old = 15,
   63         .rc_thresh_denom = 8,
   64         .rc_thresh_old = 4,
   65         .rc_avgrssi_denom = 8,
   66         .rc_avgrssi_old = 4
   67 };
   68 
   69 #ifdef interpolate
   70 #undef interpolate
   71 #endif
   72 #define interpolate(parm, old, new) ((parm##_old * (old) + \
   73                                      (parm##_denom - parm##_old) * (new)) / \
   74                                     parm##_denom)
   75 
   76 static void     rssadapt_setinterval(const struct ieee80211vap *, int);
   77 static void     rssadapt_init(struct ieee80211vap *);
   78 static void     rssadapt_deinit(struct ieee80211vap *);
   79 static void     rssadapt_updatestats(struct ieee80211_rssadapt_node *);
   80 static void     rssadapt_node_init(struct ieee80211_node *);
   81 static void     rssadapt_node_deinit(struct ieee80211_node *);
   82 static int      rssadapt_rate(struct ieee80211_node *, void *, uint32_t);
   83 static void     rssadapt_lower_rate(struct ieee80211_rssadapt_node *, int, int);
   84 static void     rssadapt_raise_rate(struct ieee80211_rssadapt_node *,
   85                         int, int);
   86 static void     rssadapt_tx_complete(const struct ieee80211vap *,
   87                         const struct ieee80211_node *, int,
   88                         void *, void *);
   89 static void     rssadapt_sysctlattach(struct ieee80211vap *,
   90                         struct sysctl_ctx_list *, struct sysctl_oid *);
   91 
   92 /* number of references from net80211 layer */
   93 static  int nrefs = 0;
   94 
   95 static const struct ieee80211_ratectl rssadapt = {
   96         .ir_name        = "rssadapt",
   97         .ir_attach      = NULL,
   98         .ir_detach      = NULL,
   99         .ir_init        = rssadapt_init,
  100         .ir_deinit      = rssadapt_deinit,
  101         .ir_node_init   = rssadapt_node_init,
  102         .ir_node_deinit = rssadapt_node_deinit,
  103         .ir_rate        = rssadapt_rate,
  104         .ir_tx_complete = rssadapt_tx_complete,
  105         .ir_tx_update   = NULL,
  106         .ir_setinterval = rssadapt_setinterval,
  107 };
  108 IEEE80211_RATECTL_MODULE(rssadapt, 1);
  109 IEEE80211_RATECTL_ALG(rssadapt, IEEE80211_RATECTL_RSSADAPT, rssadapt);
  110 
  111 static void
  112 rssadapt_setinterval(const struct ieee80211vap *vap, int msecs)
  113 {
  114         struct ieee80211_rssadapt *rs = vap->iv_rs;
  115         int t;
  116 
  117         if (!rs)
  118                 return;
  119 
  120         if (msecs < 100)
  121                 msecs = 100;
  122         t = msecs_to_ticks(msecs);
  123         rs->interval = (t < 1) ? 1 : t;
  124 }
  125 
  126 static void
  127 rssadapt_init(struct ieee80211vap *vap)
  128 {
  129         struct ieee80211_rssadapt *rs;
  130 
  131         KASSERT(vap->iv_rs == NULL, ("%s: iv_rs already initialized",
  132             __func__));
  133 
  134         nrefs++;                /* XXX locking */
  135         vap->iv_rs = rs = malloc(sizeof(struct ieee80211_rssadapt),
  136             M_80211_RATECTL, M_NOWAIT|M_ZERO);
  137         if (rs == NULL) {
  138                 if_printf(vap->iv_ifp, "couldn't alloc ratectl structure\n");
  139                 return;
  140         }
  141         rs->vap = vap;
  142         rssadapt_setinterval(vap, 500 /* msecs */);
  143         rssadapt_sysctlattach(vap, vap->iv_sysctl, vap->iv_oid);
  144 }
  145 
  146 static void
  147 rssadapt_deinit(struct ieee80211vap *vap)
  148 {
  149         free(vap->iv_rs, M_80211_RATECTL);
  150         KASSERT(nrefs > 0, ("imbalanced attach/detach"));
  151         nrefs--;                /* XXX locking */
  152 }
  153 
  154 static void
  155 rssadapt_updatestats(struct ieee80211_rssadapt_node *ra)
  156 {
  157         long interval;
  158 
  159         ra->ra_pktrate = (ra->ra_pktrate + 10*(ra->ra_nfail + ra->ra_nok))/2;
  160         ra->ra_nfail = ra->ra_nok = 0;
  161 
  162         /*
  163          * A node is eligible for its rate to be raised every 1/10 to 10
  164          * seconds, more eligible in proportion to recent packet rates.
  165          */
  166         interval = MAX(10*1000, 10*1000 / MAX(1, 10 * ra->ra_pktrate));
  167         ra->ra_raise_interval = msecs_to_ticks(interval);
  168 }
  169 
  170 static void
  171 rssadapt_node_init(struct ieee80211_node *ni)
  172 {
  173         struct ieee80211_rssadapt_node *ra;
  174         struct ieee80211vap *vap = ni->ni_vap;
  175         struct ieee80211_rssadapt *rsa = vap->iv_rs;
  176         const struct ieee80211_rateset *rs = &ni->ni_rates;
  177 
  178         if (!rsa) {
  179                 if_printf(vap->iv_ifp, "ratectl structure was not allocated, "
  180                     "per-node structure allocation skipped\n");
  181                 return;
  182         }
  183 
  184         if (ni->ni_rctls == NULL) {
  185                 ni->ni_rctls = ra = 
  186                     malloc(sizeof(struct ieee80211_rssadapt_node),
  187                         M_80211_RATECTL, M_NOWAIT|M_ZERO);
  188                 if (ra == NULL) {
  189                         if_printf(vap->iv_ifp, "couldn't alloc per-node ratectl "
  190                             "structure\n");
  191                         return;
  192                 }
  193         } else
  194                 ra = ni->ni_rctls;
  195         ra->ra_rs = rsa;
  196         ra->ra_rates = *rs;
  197         rssadapt_updatestats(ra);
  198 
  199         /* pick initial rate */
  200         for (ra->ra_rix = rs->rs_nrates - 1;
  201              ra->ra_rix > 0 && (rs->rs_rates[ra->ra_rix] & IEEE80211_RATE_VAL) > 72;
  202              ra->ra_rix--)
  203                 ;
  204         ni->ni_txrate = rs->rs_rates[ra->ra_rix] & IEEE80211_RATE_VAL;
  205         ra->ra_ticks = ticks;
  206 
  207         IEEE80211_NOTE(ni->ni_vap, IEEE80211_MSG_RATECTL, ni,
  208             "RSSADAPT initial rate %d", ni->ni_txrate);
  209 }
  210 
  211 static void
  212 rssadapt_node_deinit(struct ieee80211_node *ni)
  213 {
  214 
  215         free(ni->ni_rctls, M_80211_RATECTL);
  216 }
  217 
  218 static __inline int
  219 bucket(int pktlen)
  220 {
  221         int i, top, thridx;
  222 
  223         for (i = 0, top = IEEE80211_RSSADAPT_BKT0;
  224              i < IEEE80211_RSSADAPT_BKTS;
  225              i++, top <<= IEEE80211_RSSADAPT_BKTPOWER) {
  226                 thridx = i;
  227                 if (pktlen <= top)
  228                         break;
  229         }
  230         return thridx;
  231 }
  232 
  233 static int
  234 rssadapt_rate(struct ieee80211_node *ni, void *arg __unused, uint32_t iarg)
  235 {
  236         struct ieee80211_rssadapt_node *ra = ni->ni_rctls;
  237         u_int pktlen = iarg;
  238         const struct ieee80211_rateset *rs;
  239         uint16_t (*thrs)[IEEE80211_RATE_SIZE];
  240         int rix, rssi;
  241 
  242         /* XXX should return -1 here, but drivers may not expect this... */
  243         if (!ra)
  244         {
  245                 ni->ni_txrate = ni->ni_rates.rs_rates[0];
  246                 return 0;
  247         }
  248 
  249         rs = &ra->ra_rates;
  250         if ((ticks - ra->ra_ticks) > ra->ra_rs->interval) {
  251                 rssadapt_updatestats(ra);
  252                 ra->ra_ticks = ticks;
  253         }
  254 
  255         thrs = &ra->ra_rate_thresh[bucket(pktlen)];
  256 
  257         /* XXX this is average rssi, should be using last value */
  258         rssi = ni->ni_ic->ic_node_getrssi(ni);
  259         for (rix = rs->rs_nrates-1; rix >= 0; rix--)
  260                 if ((*thrs)[rix] < (rssi << 8))
  261                         break;
  262         if (rix != ra->ra_rix) {
  263                 /* update public rate */
  264                 ni->ni_txrate = ni->ni_rates.rs_rates[rix] & IEEE80211_RATE_VAL;
  265                 ra->ra_rix = rix;
  266 
  267                 IEEE80211_NOTE(ni->ni_vap, IEEE80211_MSG_RATECTL, ni,
  268                     "RSSADAPT new rate %d (pktlen %d rssi %d)",
  269                     ni->ni_txrate, pktlen, rssi);
  270         }
  271         return rix;
  272 }
  273 
  274 /*
  275  * Adapt the data rate to suit the conditions.  When a transmitted
  276  * packet is dropped after RAL_RSSADAPT_RETRY_LIMIT retransmissions,
  277  * raise the RSS threshold for transmitting packets of similar length at
  278  * the same data rate.
  279  */
  280 static void
  281 rssadapt_lower_rate(struct ieee80211_rssadapt_node *ra, int pktlen, int rssi)
  282 {
  283         uint16_t last_thr;
  284         uint16_t (*thrs)[IEEE80211_RATE_SIZE];
  285         u_int rix;
  286 
  287         thrs = &ra->ra_rate_thresh[bucket(pktlen)];
  288 
  289         rix = ra->ra_rix;
  290         last_thr = (*thrs)[rix];
  291         (*thrs)[rix] = interpolate(master_expavgctl.rc_thresh,
  292             last_thr, (rssi << 8));
  293 
  294         IEEE80211_DPRINTF(ra->ra_rs->vap, IEEE80211_MSG_RATECTL,
  295             "RSSADAPT lower threshold for rate %d (last_thr %d new thr %d rssi %d)\n",
  296             ra->ra_rates.rs_rates[rix + 1] & IEEE80211_RATE_VAL,
  297             last_thr, (*thrs)[rix], rssi);
  298 }
  299 
  300 static void
  301 rssadapt_raise_rate(struct ieee80211_rssadapt_node *ra, int pktlen, int rssi)
  302 {
  303         uint16_t (*thrs)[IEEE80211_RATE_SIZE];
  304         uint16_t newthr, oldthr;
  305         int rix;
  306 
  307         thrs = &ra->ra_rate_thresh[bucket(pktlen)];
  308 
  309         rix = ra->ra_rix;
  310         if ((*thrs)[rix + 1] > (*thrs)[rix]) {
  311                 oldthr = (*thrs)[rix + 1];
  312                 if ((*thrs)[rix] == 0)
  313                         newthr = (rssi << 8);
  314                 else
  315                         newthr = (*thrs)[rix];
  316                 (*thrs)[rix + 1] = interpolate(master_expavgctl.rc_decay,
  317                     oldthr, newthr);
  318 
  319                 IEEE80211_DPRINTF(ra->ra_rs->vap, IEEE80211_MSG_RATECTL,
  320                     "RSSADAPT raise threshold for rate %d (oldthr %d newthr %d rssi %d)\n",
  321                     ra->ra_rates.rs_rates[rix + 1] & IEEE80211_RATE_VAL,
  322                     oldthr, newthr, rssi);
  323 
  324                 ra->ra_last_raise = ticks;
  325         }
  326 }
  327 
  328 static void
  329 rssadapt_tx_complete(const struct ieee80211vap *vap,
  330     const struct ieee80211_node *ni, int success, void *arg1, void *arg2)
  331 {
  332         struct ieee80211_rssadapt_node *ra = ni->ni_rctls;
  333         int pktlen = *(int *)arg1, rssi = *(int *)arg2;
  334 
  335         if (!ra)
  336                 return;
  337 
  338         if (success) {
  339                 ra->ra_nok++;
  340                 if ((ra->ra_rix + 1) < ra->ra_rates.rs_nrates &&
  341                     (ticks - ra->ra_last_raise) >= ra->ra_raise_interval)
  342                         rssadapt_raise_rate(ra, pktlen, rssi);
  343         } else {
  344                 ra->ra_nfail++;
  345                 rssadapt_lower_rate(ra, pktlen, rssi);
  346         }
  347 }
  348 
  349 static int
  350 rssadapt_sysctl_interval(SYSCTL_HANDLER_ARGS)
  351 {
  352         struct ieee80211vap *vap = arg1;
  353         struct ieee80211_rssadapt *rs = vap->iv_rs;
  354         int msecs, error;
  355 
  356         if (!rs)
  357                 return ENOMEM;
  358 
  359         msecs = ticks_to_msecs(rs->interval);
  360         error = sysctl_handle_int(oidp, &msecs, 0, req);
  361         if (error || !req->newptr)
  362                 return error;
  363         rssadapt_setinterval(vap, msecs);
  364         return 0;
  365 }
  366 
  367 static void
  368 rssadapt_sysctlattach(struct ieee80211vap *vap,
  369     struct sysctl_ctx_list *ctx, struct sysctl_oid *tree)
  370 {
  371 
  372         SYSCTL_ADD_PROC(ctx, SYSCTL_CHILDREN(tree), OID_AUTO,
  373             "rssadapt_rate_interval", CTLTYPE_INT | CTLFLAG_RW, vap,
  374             0, rssadapt_sysctl_interval, "I", "rssadapt operation interval (ms)");
  375 }

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