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: releng/8.0/sys/net80211/ieee80211_rssadapt.c 178354 2008-04-20 20:35:46Z sam $        */
    2 /* $NetBSD: ieee80211_rssadapt.c,v 1.9 2005/02/26 22:45:09 perry Exp $ */
    3 /*-
    4  * Copyright (c) 2003, 2004 David Young.  All rights reserved.
    5  *
    6  * Redistribution and use in source and binary forms, with or
    7  * without modification, are permitted provided that the following
    8  * conditions are met:
    9  * 1. Redistributions of source code must retain the above copyright
   10  *    notice, this list of conditions and the following disclaimer.
   11  * 2. Redistributions in binary form must reproduce the above
   12  *    copyright notice, this list of conditions and the following
   13  *    disclaimer in the documentation and/or other materials provided
   14  *    with the distribution.
   15  * 3. The name of David Young may not be used to endorse or promote
   16  *    products derived from this software without specific prior
   17  *    written permission.
   18  *
   19  * THIS SOFTWARE IS PROVIDED BY David Young ``AS IS'' AND ANY
   20  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
   21  * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
   22  * PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL David
   23  * Young BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
   24  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
   25  * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
   26  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
   27  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
   28  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
   30  * OF SUCH DAMAGE.
   31  */
   32 #include "opt_wlan.h"
   33 
   34 #include <sys/param.h>
   35 #include <sys/kernel.h>
   36 #include <sys/module.h>
   37 #include <sys/socket.h>
   38 #include <sys/sysctl.h>
   39 
   40 #include <net/if.h>
   41 #include <net/if_media.h>
   42 
   43 #include <net80211/ieee80211_var.h>
   44 #include <net80211/ieee80211_rssadapt.h>
   45 
   46 struct rssadapt_expavgctl {
   47         /* RSS threshold decay. */
   48         u_int rc_decay_denom;
   49         u_int rc_decay_old;
   50         /* RSS threshold update. */
   51         u_int rc_thresh_denom;
   52         u_int rc_thresh_old;
   53         /* RSS average update. */
   54         u_int rc_avgrssi_denom;
   55         u_int rc_avgrssi_old;
   56 };
   57 
   58 static struct rssadapt_expavgctl master_expavgctl = {
   59         rc_decay_denom : 16,
   60         rc_decay_old : 15,
   61         rc_thresh_denom : 8,
   62         rc_thresh_old : 4,
   63         rc_avgrssi_denom : 8,
   64         rc_avgrssi_old : 4
   65 };
   66 
   67 #ifdef interpolate
   68 #undef interpolate
   69 #endif
   70 #define interpolate(parm, old, new) ((parm##_old * (old) + \
   71                                      (parm##_denom - parm##_old) * (new)) / \
   72                                     parm##_denom)
   73 
   74 static void rssadapt_sysctlattach(struct ieee80211_rssadapt *rs,
   75         struct sysctl_ctx_list *ctx, struct sysctl_oid *tree);
   76 
   77 /* number of references from net80211 layer */
   78 static  int nrefs = 0;
   79 
   80 void
   81 ieee80211_rssadapt_setinterval(struct ieee80211_rssadapt *rs, int msecs)
   82 {
   83         int t;
   84 
   85         if (msecs < 100)
   86                 msecs = 100;
   87         t = msecs_to_ticks(msecs);
   88         rs->interval = (t < 1) ? 1 : t;
   89 }
   90 
   91 void
   92 ieee80211_rssadapt_init(struct ieee80211_rssadapt *rs, struct ieee80211vap *vap, int interval)
   93 {
   94         rs->vap = vap;
   95         ieee80211_rssadapt_setinterval(rs, interval);
   96 
   97         rssadapt_sysctlattach(rs, vap->iv_sysctl, vap->iv_oid);
   98 }
   99 
  100 void
  101 ieee80211_rssadapt_cleanup(struct ieee80211_rssadapt *rs)
  102 {
  103 }
  104 
  105 static void
  106 rssadapt_updatestats(struct ieee80211_rssadapt_node *ra)
  107 {
  108         long interval;
  109 
  110         ra->ra_pktrate = (ra->ra_pktrate + 10*(ra->ra_nfail + ra->ra_nok))/2;
  111         ra->ra_nfail = ra->ra_nok = 0;
  112 
  113         /*
  114          * A node is eligible for its rate to be raised every 1/10 to 10
  115          * seconds, more eligible in proportion to recent packet rates.
  116          */
  117         interval = MAX(10*1000, 10*1000 / MAX(1, 10 * ra->ra_pktrate));
  118         ra->ra_raise_interval = msecs_to_ticks(interval);
  119 }
  120 
  121 void
  122 ieee80211_rssadapt_node_init(struct ieee80211_rssadapt *rsa,
  123     struct ieee80211_rssadapt_node *ra, struct ieee80211_node *ni)
  124 {
  125         const struct ieee80211_rateset *rs = &ni->ni_rates;
  126 
  127         ra->ra_rs = rsa;
  128         ra->ra_rates = *rs;
  129         rssadapt_updatestats(ra);
  130 
  131         /* pick initial rate */
  132         for (ra->ra_rix = rs->rs_nrates - 1;
  133              ra->ra_rix > 0 && (rs->rs_rates[ra->ra_rix] & IEEE80211_RATE_VAL) > 72;
  134              ra->ra_rix--)
  135                 ;
  136         ni->ni_txrate = rs->rs_rates[ra->ra_rix] & IEEE80211_RATE_VAL;
  137         ra->ra_ticks = ticks;
  138 
  139         IEEE80211_NOTE(ni->ni_vap, IEEE80211_MSG_RATECTL, ni,
  140             "RSSADAPT initial rate %d", ni->ni_txrate);
  141 }
  142 
  143 static __inline int
  144 bucket(int pktlen)
  145 {
  146         int i, top, thridx;
  147 
  148         for (i = 0, top = IEEE80211_RSSADAPT_BKT0;
  149              i < IEEE80211_RSSADAPT_BKTS;
  150              i++, top <<= IEEE80211_RSSADAPT_BKTPOWER) {
  151                 thridx = i;
  152                 if (pktlen <= top)
  153                         break;
  154         }
  155         return thridx;
  156 }
  157 
  158 int
  159 ieee80211_rssadapt_choose(struct ieee80211_node *ni,
  160     struct ieee80211_rssadapt_node *ra, u_int pktlen)
  161 {
  162         const struct ieee80211_rateset *rs = &ra->ra_rates;
  163         uint16_t (*thrs)[IEEE80211_RATE_SIZE];
  164         int rix, rssi;
  165 
  166         if ((ticks - ra->ra_ticks) > ra->ra_rs->interval) {
  167                 rssadapt_updatestats(ra);
  168                 ra->ra_ticks = ticks;
  169         }
  170 
  171         thrs = &ra->ra_rate_thresh[bucket(pktlen)];
  172 
  173         /* XXX this is average rssi, should be using last value */
  174         rssi = ni->ni_ic->ic_node_getrssi(ni);
  175         for (rix = rs->rs_nrates-1; rix >= 0; rix--)
  176                 if ((*thrs)[rix] < (rssi << 8))
  177                         break;
  178         if (rix != ra->ra_rix) {
  179                 /* update public rate */
  180                 ni->ni_txrate = ni->ni_rates.rs_rates[rix] & IEEE80211_RATE_VAL;
  181                 ra->ra_rix = rix;
  182 
  183                 IEEE80211_NOTE(ni->ni_vap, IEEE80211_MSG_RATECTL, ni,
  184                     "RSSADAPT new rate %d (pktlen %d rssi %d)",
  185                     ni->ni_txrate, pktlen, rssi);
  186         }
  187         return rix;
  188 }
  189 
  190 /*
  191  * Adapt the data rate to suit the conditions.  When a transmitted
  192  * packet is dropped after RAL_RSSADAPT_RETRY_LIMIT retransmissions,
  193  * raise the RSS threshold for transmitting packets of similar length at
  194  * the same data rate.
  195  */
  196 void
  197 ieee80211_rssadapt_lower_rate(struct ieee80211_rssadapt_node *ra,
  198     int pktlen, int rssi)
  199 {
  200         uint16_t last_thr;
  201         uint16_t (*thrs)[IEEE80211_RATE_SIZE];
  202         u_int rix;
  203 
  204         thrs = &ra->ra_rate_thresh[bucket(pktlen)];
  205 
  206         rix = ra->ra_rix;
  207         last_thr = (*thrs)[rix];
  208         (*thrs)[rix] = interpolate(master_expavgctl.rc_thresh,
  209             last_thr, (rssi << 8));
  210 
  211         IEEE80211_DPRINTF(ra->ra_rs->vap, IEEE80211_MSG_RATECTL,
  212             "RSSADAPT lower threshold for rate %d (last_thr %d new thr %d rssi %d)\n",
  213             ra->ra_rates.rs_rates[rix + 1] & IEEE80211_RATE_VAL,
  214             last_thr, (*thrs)[rix], rssi);
  215 }
  216 
  217 void
  218 ieee80211_rssadapt_raise_rate(struct ieee80211_rssadapt_node *ra,
  219     int pktlen, int rssi)
  220 {
  221         uint16_t (*thrs)[IEEE80211_RATE_SIZE];
  222         uint16_t newthr, oldthr;
  223         int rix;
  224 
  225         thrs = &ra->ra_rate_thresh[bucket(pktlen)];
  226 
  227         rix = ra->ra_rix;
  228         if ((*thrs)[rix + 1] > (*thrs)[rix]) {
  229                 oldthr = (*thrs)[rix + 1];
  230                 if ((*thrs)[rix] == 0)
  231                         newthr = (rssi << 8);
  232                 else
  233                         newthr = (*thrs)[rix];
  234                 (*thrs)[rix + 1] = interpolate(master_expavgctl.rc_decay,
  235                     oldthr, newthr);
  236 
  237                 IEEE80211_DPRINTF(ra->ra_rs->vap, IEEE80211_MSG_RATECTL,
  238                     "RSSADAPT raise threshold for rate %d (oldthr %d newthr %d rssi %d)\n",
  239                     ra->ra_rates.rs_rates[rix + 1] & IEEE80211_RATE_VAL,
  240                     oldthr, newthr, rssi);
  241 
  242                 ra->ra_last_raise = ticks;
  243         }
  244 }
  245 
  246 static int
  247 rssadapt_sysctl_interval(SYSCTL_HANDLER_ARGS)
  248 {
  249         struct ieee80211_rssadapt *rs = arg1;
  250         int msecs = ticks_to_msecs(rs->interval);
  251         int error;
  252 
  253         error = sysctl_handle_int(oidp, &msecs, 0, req);
  254         if (error || !req->newptr)
  255                 return error;
  256         ieee80211_rssadapt_setinterval(rs, msecs);
  257         return 0;
  258 }
  259 
  260 static void
  261 rssadapt_sysctlattach(struct ieee80211_rssadapt *rs,
  262     struct sysctl_ctx_list *ctx, struct sysctl_oid *tree)
  263 {
  264 
  265         SYSCTL_ADD_PROC(ctx, SYSCTL_CHILDREN(tree), OID_AUTO,
  266             "rssadapt_rate_interval", CTLTYPE_INT | CTLFLAG_RW, rs,
  267             0, rssadapt_sysctl_interval, "I", "rssadapt operation interval (ms)");
  268 }
  269 
  270 /*
  271  * Module glue.
  272  */
  273 IEEE80211_RATE_MODULE(rssadapt, 1);

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