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 /*      $OpenBSD: ieee80211_rssadapt.c,v 1.11 2014/12/23 03:24:08 tedu Exp $    */
    2 /*      $NetBSD: ieee80211_rssadapt.c,v 1.7 2004/05/25 04:33:59 dyoung Exp $    */
    3 
    4 /*-
    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  *
   17  * THIS SOFTWARE IS PROVIDED BY David Young ``AS IS'' AND ANY
   18  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
   19  * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
   20  * PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL David
   21  * Young BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
   22  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
   23  * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
   24  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
   25  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
   26  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   27  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
   28  * OF SUCH DAMAGE.
   29  */
   30 
   31 #include <sys/param.h>
   32 #include <sys/systm.h>
   33 #include <sys/kernel.h>
   34 #include <sys/socket.h>
   35 
   36 #include <net/if.h>
   37 #include <net/if_media.h>
   38 
   39 #include <netinet/in.h>
   40 #include <netinet/if_ether.h>
   41 
   42 #include <net80211/ieee80211_var.h>
   43 #include <net80211/ieee80211_rssadapt.h>
   44 
   45 #ifdef interpolate
   46 #undef interpolate
   47 #endif
   48 #define interpolate(parm, old, new)                             \
   49         ((parm##_old * (old) +                                  \
   50         (parm##_denom - parm##_old) * (new)) / parm##_denom)
   51 
   52 #ifdef IEEE80211_DEBUG
   53 static  struct timeval lastrateadapt;   /* time of last rate adaptation msg */
   54 static  int currssadaptps = 0;          /* rate-adaptation msgs this second */
   55 static  int ieee80211_adaptrate = 4;    /* rate-adaptation max msgs/sec */
   56 
   57 #define RSSADAPT_DO_PRINT() \
   58         ((ieee80211_rssadapt_debug > 0) && \
   59          ppsratecheck(&lastrateadapt, &currssadaptps, ieee80211_adaptrate))
   60 #define RSSADAPT_PRINTF(X) \
   61         if (RSSADAPT_DO_PRINT()) \
   62                 printf X
   63 
   64 int ieee80211_rssadapt_debug = 0;
   65 
   66 #else
   67 #define RSSADAPT_DO_PRINT() (0)
   68 #define RSSADAPT_PRINTF(X)
   69 #endif
   70 
   71 static const struct ieee80211_rssadapt_expavgctl master_expavgctl = {
   72         .rc_decay_denom         = 16,
   73         .rc_decay_old           = 15,
   74         .rc_thresh_denom        = 8,
   75         .rc_thresh_old          = 4,
   76         .rc_avgrssi_denom       = 8,
   77         .rc_avgrssi_old         = 4
   78 };
   79 
   80 int
   81 ieee80211_rssadapt_choose(struct ieee80211_rssadapt *ra,
   82     const struct ieee80211_rateset *rs, const struct ieee80211_frame *wh,
   83     u_int len, int fixed_rate, const char *dvname, int do_not_adapt)
   84 {
   85         u_int16_t (*thrs)[IEEE80211_RATE_SIZE];
   86         int flags = 0, i, rateidx = 0, thridx, top;
   87 
   88         if ((wh->i_fc[0] & IEEE80211_FC0_TYPE_MASK) == IEEE80211_FC0_TYPE_CTL)
   89                 flags |= IEEE80211_RATE_BASIC;
   90 
   91         for (i = 0, top = IEEE80211_RSSADAPT_BKT0;
   92              i < IEEE80211_RSSADAPT_BKTS;
   93              i++, top <<= IEEE80211_RSSADAPT_BKTPOWER) {
   94                 thridx = i;
   95                 if (len <= top)
   96                         break;
   97         }
   98 
   99         thrs = &ra->ra_rate_thresh[thridx];
  100 
  101         if (fixed_rate != -1) {
  102                 if ((rs->rs_rates[fixed_rate] & flags) == flags) {
  103                         rateidx = fixed_rate;
  104                         goto out;
  105                 }
  106                 flags |= IEEE80211_RATE_BASIC;
  107                 i = fixed_rate;
  108         } else
  109                 i = rs->rs_nrates;
  110 
  111         while (--i >= 0) {
  112                 rateidx = i;
  113                 if ((rs->rs_rates[i] & flags) != flags)
  114                         continue;
  115                 if (do_not_adapt)
  116                         break;
  117                 if ((*thrs)[i] < ra->ra_avg_rssi)
  118                         break;
  119         }
  120 
  121 out:
  122 #ifdef IEEE80211_DEBUG
  123         if (ieee80211_rssadapt_debug && dvname != NULL) {
  124                 printf("%s: dst %s threshold[%d, %d.%d] %d < %d\n",
  125                     dvname, ether_sprintf((u_int8_t *)wh->i_addr1), len,
  126                     (rs->rs_rates[rateidx] & IEEE80211_RATE_VAL) / 2,
  127                     (rs->rs_rates[rateidx] & IEEE80211_RATE_VAL) * 5 % 10,
  128                     (*thrs)[rateidx], ra->ra_avg_rssi);
  129         }
  130 #endif /* IEEE80211_DEBUG */
  131         return rateidx;
  132 }
  133 
  134 void
  135 ieee80211_rssadapt_updatestats(struct ieee80211_rssadapt *ra)
  136 {
  137         long interval;
  138 
  139         ra->ra_pktrate =
  140             (ra->ra_pktrate + 10 * (ra->ra_nfail + ra->ra_nok)) / 2;
  141         ra->ra_nfail = ra->ra_nok = 0;
  142 
  143         /* a node is eligible for its rate to be raised every 1/10 to 10
  144          * seconds, more eligible in proportion to recent packet rates.
  145          */
  146         interval = MAX(100000, 10000000 / MAX(1, 10 * ra->ra_pktrate));
  147         ra->ra_raise_interval.tv_sec = interval / (1000 * 1000);
  148         ra->ra_raise_interval.tv_usec = interval % (1000 * 1000);
  149 }
  150 
  151 void
  152 ieee80211_rssadapt_input(struct ieee80211com *ic,
  153     const struct ieee80211_node *ni, struct ieee80211_rssadapt *ra, int rssi)
  154 {
  155 #ifdef IEEE80211_DEBUG
  156         int last_avg_rssi = ra->ra_avg_rssi;
  157 #endif
  158 
  159         ra->ra_avg_rssi = interpolate(master_expavgctl.rc_avgrssi,
  160             ra->ra_avg_rssi, (rssi << 8));
  161 
  162         RSSADAPT_PRINTF(("%s: src %s rssi %d avg %d -> %d\n",
  163             ic->ic_if.if_xname, ether_sprintf((u_int8_t *)ni->ni_macaddr),
  164             rssi, last_avg_rssi, ra->ra_avg_rssi));
  165 }
  166 
  167 /*
  168  * Adapt the data rate to suit the conditions.  When a transmitted
  169  * packet is dropped after IEEE80211_RSSADAPT_RETRY_LIMIT retransmissions,
  170  * raise the RSS threshold for transmitting packets of similar length at
  171  * the same data rate.
  172  */
  173 void
  174 ieee80211_rssadapt_lower_rate(struct ieee80211com *ic,
  175     const struct ieee80211_node *ni, struct ieee80211_rssadapt *ra,
  176     const struct ieee80211_rssdesc *id)
  177 {
  178         const struct ieee80211_rateset *rs = &ni->ni_rates;
  179         u_int16_t last_thr;
  180         u_int i, thridx, top;
  181 
  182         ra->ra_nfail++;
  183 
  184         if (id->id_rateidx >= rs->rs_nrates) {
  185                 RSSADAPT_PRINTF(("ieee80211_rssadapt_lower_rate: "
  186                     "%s rate #%d > #%d out of bounds\n",
  187                     ether_sprintf((u_int8_t *)ni->ni_macaddr), id->id_rateidx,
  188                     rs->rs_nrates - 1));
  189                 return;
  190         }
  191 
  192         for (i = 0, top = IEEE80211_RSSADAPT_BKT0;
  193              i < IEEE80211_RSSADAPT_BKTS;
  194              i++, top <<= IEEE80211_RSSADAPT_BKTPOWER) {
  195                 thridx = i;
  196                 if (id->id_len <= top)
  197                         break;
  198         }
  199 
  200         last_thr = ra->ra_rate_thresh[thridx][id->id_rateidx];
  201         ra->ra_rate_thresh[thridx][id->id_rateidx] =
  202             interpolate(master_expavgctl.rc_thresh, last_thr,
  203             (id->id_rssi << 8));
  204 
  205         RSSADAPT_PRINTF(("%s: dst %s rssi %d threshold[%d, %d.%d] %d -> %d\n",
  206             ic->ic_if.if_xname, ether_sprintf((u_int8_t *)ni->ni_macaddr),
  207             id->id_rssi, id->id_len,
  208             (rs->rs_rates[id->id_rateidx] & IEEE80211_RATE_VAL) / 2,
  209             (rs->rs_rates[id->id_rateidx] & IEEE80211_RATE_VAL) * 5 % 10,
  210             last_thr, ra->ra_rate_thresh[thridx][id->id_rateidx]));
  211 }
  212 
  213 void
  214 ieee80211_rssadapt_raise_rate(struct ieee80211com *ic,
  215     struct ieee80211_rssadapt *ra, const struct ieee80211_rssdesc *id)
  216 {
  217         u_int16_t (*thrs)[IEEE80211_RATE_SIZE], newthr, oldthr;
  218         const struct ieee80211_node *ni = id->id_node;
  219         const struct ieee80211_rateset *rs = &ni->ni_rates;
  220         int i, rate, top;
  221 #ifdef IEEE80211_DEBUG
  222         int j;
  223 #endif
  224 
  225         ra->ra_nok++;
  226 
  227         if (!ratecheck(&ra->ra_last_raise, &ra->ra_raise_interval))
  228                 return;
  229 
  230         for (i = 0, top = IEEE80211_RSSADAPT_BKT0;
  231              i < IEEE80211_RSSADAPT_BKTS;
  232              i++, top <<= IEEE80211_RSSADAPT_BKTPOWER) {
  233                 thrs = &ra->ra_rate_thresh[i];
  234                 if (id->id_len <= top)
  235                         break;
  236         }
  237 
  238         if (id->id_rateidx + 1 < rs->rs_nrates &&
  239             (*thrs)[id->id_rateidx + 1] > (*thrs)[id->id_rateidx]) {
  240                 rate = (rs->rs_rates[id->id_rateidx + 1] & IEEE80211_RATE_VAL);
  241 
  242                 RSSADAPT_PRINTF(("%s: threshold[%d, %d.%d] decay %d ",
  243                     ic->ic_if.if_xname, IEEE80211_RSSADAPT_BKT0 <<
  244                         (IEEE80211_RSSADAPT_BKTPOWER * i),
  245                     rate / 2, rate * 5 % 10, (*thrs)[id->id_rateidx + 1]));
  246                 oldthr = (*thrs)[id->id_rateidx + 1];
  247                 if ((*thrs)[id->id_rateidx] == 0)
  248                         newthr = ra->ra_avg_rssi;
  249                 else
  250                         newthr = (*thrs)[id->id_rateidx];
  251                 (*thrs)[id->id_rateidx + 1] =
  252                     interpolate(master_expavgctl.rc_decay, oldthr, newthr);
  253 
  254                 RSSADAPT_PRINTF(("-> %d\n", (*thrs)[id->id_rateidx + 1]));
  255         }
  256 
  257 #ifdef IEEE80211_DEBUG
  258         if (RSSADAPT_DO_PRINT()) {
  259                 printf("%s: dst %s thresholds\n", ic->ic_if.if_xname,
  260                     ether_sprintf((u_int8_t *)ni->ni_macaddr));
  261                 for (i = 0; i < IEEE80211_RSSADAPT_BKTS; i++) {
  262                         printf("%d-byte", IEEE80211_RSSADAPT_BKT0 <<
  263                             (IEEE80211_RSSADAPT_BKTPOWER * i));
  264                         for (j = 0; j < rs->rs_nrates; j++) {
  265                                 rate = (rs->rs_rates[j] & IEEE80211_RATE_VAL);
  266                                 printf(", T[%d.%d] = %d", rate / 2,
  267                                     rate * 5 % 10, ra->ra_rate_thresh[i][j]);
  268                         }
  269                         printf("\n");
  270                 }
  271         }
  272 #endif /* IEEE80211_DEBUG */
  273 }

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