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 /* $NetBSD: ieee80211_rssadapt.c,v 1.9 2005/02/26 22:45:09 perry Exp $ */
    2 /*-
    3  * Copyright (c) 2003, 2004 David Young.  All rights reserved.
    4  *
    5  * Redistribution and use in source and binary forms, with or
    6  * without modification, are permitted provided that the following
    7  * conditions are met:
    8  * 1. Redistributions of source code must retain the above copyright
    9  *    notice, this list of conditions and the following disclaimer.
   10  * 2. Redistributions in binary form must reproduce the above
   11  *    copyright notice, this list of conditions and the following
   12  *    disclaimer in the documentation and/or other materials provided
   13  *    with the distribution.
   14  * 3. The name of David Young may not be used to endorse or promote
   15  *    products derived from this software without specific prior
   16  *    written permission.
   17  *
   18  * THIS SOFTWARE IS PROVIDED BY David Young ``AS IS'' AND ANY
   19  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
   20  * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
   21  * PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL David
   22  * Young BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
   23  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
   24  * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
   25  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
   26  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
   27  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
   29  * OF SUCH DAMAGE.
   30  */
   31 
   32 #include <sys/param.h>
   33 #include <sys/types.h>
   34 #include <sys/kernel.h>         /* for hz */
   35 #include <sys/sysctl.h>
   36 
   37 #include <net/if.h>
   38 #include <net/if_media.h>
   39 #include <net/if_ether.h>
   40 
   41 #include <net80211/ieee80211_var.h>
   42 #include <net80211/ieee80211.h>
   43 #include <net80211/ieee80211_compat.h>
   44 #include <net80211/ieee80211_rssadapt.h>
   45 
   46 #ifdef interpolate
   47 #undef interpolate
   48 #endif
   49 #define interpolate(parm, old, new) ((parm##_old * (old) + \
   50                                      (parm##_denom - parm##_old) * (new)) / \
   51                                     parm##_denom)
   52 
   53 #ifdef IEEE80211_DEBUG
   54 static  struct timeval lastrateadapt;   /* time of last rate adaptation msg */
   55 static  int currssadaptps = 0;          /* rate-adaptation msgs this second */
   56 static  int ieee80211_adaptrate = 4;    /* rate-adaptation max msgs/sec */
   57 
   58 #define RSSADAPT_DO_PRINT() \
   59         ((ieee80211_rssadapt_debug > 0) && \
   60          ppsratecheck(&lastrateadapt, &currssadaptps, ieee80211_adaptrate))
   61 #define RSSADAPT_PRINTF(X) \
   62         if (RSSADAPT_DO_PRINT()) \
   63                 printf X
   64 
   65 int ieee80211_rssadapt_debug = 0;
   66 
   67 #else
   68 #define RSSADAPT_DO_PRINT() (0)
   69 #define RSSADAPT_PRINTF(X)
   70 #endif
   71 
   72 static struct ieee80211_rssadapt_expavgctl master_expavgctl = {
   73         rc_decay_denom : 16,
   74         rc_decay_old : 15,
   75         rc_thresh_denom : 8,
   76         rc_thresh_old : 4,
   77         rc_avgrssi_denom : 8,
   78         rc_avgrssi_old : 4
   79 };
   80 
   81 #ifdef __NetBSD__
   82 #ifdef IEEE80211_DEBUG
   83 /* TBD factor with sysctl_ath_verify, sysctl_ieee80211_verify. */
   84 static int
   85 sysctl_ieee80211_rssadapt_debug(SYSCTLFN_ARGS)
   86 {
   87         int error, t;
   88         struct sysctlnode node;
   89 
   90         node = *rnode;
   91         t = *(int*)rnode->sysctl_data;
   92         node.sysctl_data = &t;
   93         error = sysctl_lookup(SYSCTLFN_CALL(&node));
   94         if (error || newp == NULL)
   95                 return (error);
   96 
   97         if (t < 0 || t > 2)
   98                 return (EINVAL);
   99         *(int*)rnode->sysctl_data = t;
  100 
  101         return (0);
  102 }
  103 #endif /* IEEE80211_DEBUG */
  104 
  105 /* TBD factor with sysctl_ath_verify, sysctl_ieee80211_verify. */
  106 static int
  107 sysctl_ieee80211_rssadapt_expavgctl(SYSCTLFN_ARGS)
  108 {
  109         struct ieee80211_rssadapt_expavgctl rc;
  110         int error;
  111         struct sysctlnode node;
  112 
  113         node = *rnode;
  114         rc = *(struct ieee80211_rssadapt_expavgctl *)rnode->sysctl_data;
  115         node.sysctl_data = &rc;
  116         error = sysctl_lookup(SYSCTLFN_CALL(&node));
  117         if (error || newp == NULL)
  118                 return (error);
  119 
  120         if (rc.rc_decay_old < 0 ||
  121             rc.rc_decay_denom < rc.rc_decay_old)
  122                 return (EINVAL);
  123 
  124         if (rc.rc_thresh_old < 0 ||
  125             rc.rc_thresh_denom < rc.rc_thresh_old)
  126                 return (EINVAL);
  127 
  128         if (rc.rc_avgrssi_old < 0 ||
  129             rc.rc_avgrssi_denom < rc.rc_avgrssi_old)
  130                 return (EINVAL);
  131 
  132         *(struct ieee80211_rssadapt_expavgctl *)rnode->sysctl_data = rc;
  133 
  134         return (0);
  135 }
  136 
  137 /*
  138  * Setup sysctl(3) MIB, net.ieee80211.*
  139  *
  140  * TBD condition CTLFLAG_PERMANENT on being an LKM or not
  141  */
  142 SYSCTL_SETUP(sysctl_ieee80211_rssadapt,
  143     "sysctl ieee80211 rssadapt subtree setup")
  144 {
  145         int rc;
  146         struct sysctlnode *node;
  147 
  148         if ((rc = sysctl_createv(clog, 0, NULL, &node,
  149             CTLFLAG_PERMANENT, CTLTYPE_NODE, "net", NULL,
  150             NULL, 0, NULL, 0, CTL_NET, CTL_EOL)) != 0)
  151                 goto err;
  152 
  153         if ((rc = sysctl_createv(clog, 0, &node, &node,
  154             CTLFLAG_PERMANENT, CTLTYPE_NODE, "link", NULL,
  155             NULL, 0, NULL, 0, PF_LINK, CTL_EOL)) != 0)
  156                 goto err;
  157 
  158         if ((rc = sysctl_createv(clog, 0, &node, &node,
  159             CTLFLAG_PERMANENT, CTLTYPE_NODE, "ieee80211", NULL,
  160             NULL, 0, NULL, 0, CTL_CREATE, CTL_EOL)) != 0)
  161                 goto err;
  162 
  163         if ((rc = sysctl_createv(clog, 0, &node, &node,
  164             CTLFLAG_PERMANENT, CTLTYPE_NODE, "rssadapt",
  165             SYSCTL_DESCR("Received Signal Strength adaptation controls"),
  166             NULL, 0, NULL, 0, CTL_CREATE, CTL_EOL)) != 0)
  167                 goto err;
  168 
  169 #ifdef IEEE80211_DEBUG
  170         /* control debugging printfs */
  171         if ((rc = sysctl_createv(clog, 0, &node, NULL,
  172             CTLFLAG_PERMANENT|CTLFLAG_READWRITE, CTLTYPE_INT, "debug",
  173             SYSCTL_DESCR("Enable RSS adaptation debugging output"),
  174             sysctl_ieee80211_rssadapt_debug, 0, &ieee80211_rssadapt_debug, 0,
  175             CTL_CREATE, CTL_EOL)) != 0)
  176                 goto err;
  177 #endif /* IEEE80211_DEBUG */
  178 
  179         /* control rate of decay for exponential averages */
  180         if ((rc = sysctl_createv(clog, 0, &node, NULL,
  181             CTLFLAG_PERMANENT|CTLFLAG_READWRITE, CTLTYPE_STRUCT,
  182             "expavgctl", SYSCTL_DESCR("RSS exponential averaging control"),
  183             sysctl_ieee80211_rssadapt_expavgctl, 0,
  184             &master_expavgctl, sizeof(master_expavgctl), CTL_CREATE,
  185             CTL_EOL)) != 0)
  186                 goto err;
  187 
  188         return;
  189 err:
  190         printf("%s: sysctl_createv failed (rc = %d)\n", __func__, rc);
  191 }
  192 #endif /* __NetBSD__ */
  193 
  194 int
  195 ieee80211_rssadapt_choose(struct ieee80211_rssadapt *ra,
  196     struct ieee80211_rateset *rs, struct ieee80211_frame *wh, u_int len,
  197     int fixed_rate, const char *dvname, int do_not_adapt)
  198 {
  199         u_int16_t (*thrs)[IEEE80211_RATE_SIZE];
  200         int flags = 0, i, rateidx = 0, thridx, top;
  201 
  202         if ((wh->i_fc[0] & IEEE80211_FC0_TYPE_MASK) == IEEE80211_FC0_TYPE_CTL)
  203                 flags |= IEEE80211_RATE_BASIC;
  204 
  205         for (i = 0, top = IEEE80211_RSSADAPT_BKT0;
  206              i < IEEE80211_RSSADAPT_BKTS;
  207              i++, top <<= IEEE80211_RSSADAPT_BKTPOWER) {
  208                 thridx = i;
  209                 if (len <= top)
  210                         break;
  211         }
  212 
  213         thrs = &ra->ra_rate_thresh[thridx];
  214 
  215         if (fixed_rate != -1) {
  216                 if ((rs->rs_rates[fixed_rate] & flags) == flags) {
  217                         rateidx = fixed_rate;
  218                         goto out;
  219                 }
  220                 flags |= IEEE80211_RATE_BASIC;
  221                 i = fixed_rate;
  222         } else
  223                 i = rs->rs_nrates;
  224 
  225         while (--i >= 0) {
  226                 rateidx = i;
  227                 if ((rs->rs_rates[i] & flags) != flags)
  228                         continue;
  229                 if (do_not_adapt)
  230                         break;
  231                 if ((*thrs)[i] < ra->ra_avg_rssi)
  232                         break;
  233         }
  234 
  235 out:
  236 #ifdef IEEE80211_DEBUG
  237         if (ieee80211_rssadapt_debug && dvname != NULL) {
  238                 printf("%s: dst %s threshold[%d, %d.%d] %d < %d\n",
  239                     dvname, ether_sprintf(wh->i_addr1), len,
  240                     (rs->rs_rates[rateidx] & IEEE80211_RATE_VAL) / 2,
  241                     (rs->rs_rates[rateidx] & IEEE80211_RATE_VAL) * 5 % 10,
  242                     (*thrs)[rateidx], ra->ra_avg_rssi);
  243         }
  244 #endif /* IEEE80211_DEBUG */
  245         return rateidx;
  246 }
  247 
  248 void
  249 ieee80211_rssadapt_updatestats(struct ieee80211_rssadapt *ra)
  250 {
  251         long interval;
  252 
  253         ra->ra_pktrate =
  254             (ra->ra_pktrate + 10 * (ra->ra_nfail + ra->ra_nok)) / 2;
  255         ra->ra_nfail = ra->ra_nok = 0;
  256 
  257         /* a node is eligible for its rate to be raised every 1/10 to 10
  258          * seconds, more eligible in proportion to recent packet rates.
  259          */
  260         interval = MAX(100000, 10000000 / MAX(1, 10 * ra->ra_pktrate));
  261         ra->ra_raise_interval.tv_sec = interval / (1000 * 1000);
  262         ra->ra_raise_interval.tv_usec = interval % (1000 * 1000);
  263 }
  264 
  265 void
  266 ieee80211_rssadapt_input(struct ieee80211com *ic, struct ieee80211_node *ni,
  267     struct ieee80211_rssadapt *ra, int rssi)
  268 {
  269 #ifdef IEEE80211_DEBUG
  270         int last_avg_rssi = ra->ra_avg_rssi;
  271 #endif
  272 
  273         ra->ra_avg_rssi = interpolate(master_expavgctl.rc_avgrssi,
  274                                       ra->ra_avg_rssi, (rssi << 8));
  275 
  276         RSSADAPT_PRINTF(("%s: src %s rssi %d avg %d -> %d\n",
  277             ic->ic_if.if_xname, ether_sprintf(ni->ni_macaddr),
  278             rssi, last_avg_rssi, ra->ra_avg_rssi));
  279 }
  280 
  281 /*
  282  * Adapt the data rate to suit the conditions.  When a transmitted
  283  * packet is dropped after IEEE80211_RSSADAPT_RETRY_LIMIT retransmissions,
  284  * raise the RSS threshold for transmitting packets of similar length at
  285  * the same data rate.
  286  */
  287 void
  288 ieee80211_rssadapt_lower_rate(struct ieee80211com *ic,
  289     struct ieee80211_node *ni, struct ieee80211_rssadapt *ra,
  290     struct ieee80211_rssdesc *id)
  291 {
  292         struct ieee80211_rateset *rs = &ni->ni_rates;
  293         u_int16_t last_thr;
  294         u_int i, thridx, top;
  295 
  296         ra->ra_nfail++;
  297 
  298         if (id->id_rateidx >= rs->rs_nrates) {
  299                 RSSADAPT_PRINTF(("ieee80211_rssadapt_lower_rate: "
  300                     "%s rate #%d > #%d out of bounds\n",
  301                     ether_sprintf(ni->ni_macaddr), id->id_rateidx,
  302                         rs->rs_nrates - 1));
  303                 return;
  304         }
  305 
  306         for (i = 0, top = IEEE80211_RSSADAPT_BKT0;
  307              i < IEEE80211_RSSADAPT_BKTS;
  308              i++, top <<= IEEE80211_RSSADAPT_BKTPOWER) {
  309                 thridx = i;
  310                 if (id->id_len <= top)
  311                         break;
  312         }
  313 
  314         last_thr = ra->ra_rate_thresh[thridx][id->id_rateidx];
  315         ra->ra_rate_thresh[thridx][id->id_rateidx] =
  316             interpolate(master_expavgctl.rc_thresh, last_thr,
  317                         (id->id_rssi << 8));
  318 
  319         RSSADAPT_PRINTF(("%s: dst %s rssi %d threshold[%d, %d.%d] %d -> %d\n",
  320             ic->ic_if.if_xname, ether_sprintf(ni->ni_macaddr),
  321             id->id_rssi, id->id_len,
  322             (rs->rs_rates[id->id_rateidx] & IEEE80211_RATE_VAL) / 2,
  323             (rs->rs_rates[id->id_rateidx] & IEEE80211_RATE_VAL) * 5 % 10,
  324             last_thr, ra->ra_rate_thresh[thridx][id->id_rateidx]));
  325 }
  326 
  327 void
  328 ieee80211_rssadapt_raise_rate(struct ieee80211com *ic,
  329     struct ieee80211_rssadapt *ra, struct ieee80211_rssdesc *id)
  330 {
  331         u_int16_t (*thrs)[IEEE80211_RATE_SIZE], newthr, oldthr;
  332         struct ieee80211_node *ni = id->id_node;
  333         struct ieee80211_rateset *rs = &ni->ni_rates;
  334         int i, rate, top;
  335 #ifdef IEEE80211_DEBUG
  336         int j;
  337 #endif
  338 
  339         ra->ra_nok++;
  340 
  341         if (!ratecheck(&ra->ra_last_raise, &ra->ra_raise_interval))
  342                 return;
  343 
  344         for (i = 0, top = IEEE80211_RSSADAPT_BKT0;
  345              i < IEEE80211_RSSADAPT_BKTS;
  346              i++, top <<= IEEE80211_RSSADAPT_BKTPOWER) {
  347                 thrs = &ra->ra_rate_thresh[i];
  348                 if (id->id_len <= top)
  349                         break;
  350         }
  351 
  352         if (id->id_rateidx + 1 < rs->rs_nrates &&
  353             (*thrs)[id->id_rateidx + 1] > (*thrs)[id->id_rateidx]) {
  354                 rate = (rs->rs_rates[id->id_rateidx + 1] & IEEE80211_RATE_VAL);
  355 
  356                 RSSADAPT_PRINTF(("%s: threshold[%d, %d.%d] decay %d ",
  357                     ic->ic_if.if_xname,
  358                     IEEE80211_RSSADAPT_BKT0 << (IEEE80211_RSSADAPT_BKTPOWER* i),
  359                     rate / 2, rate * 5 % 10, (*thrs)[id->id_rateidx + 1]));
  360                 oldthr = (*thrs)[id->id_rateidx + 1];
  361                 if ((*thrs)[id->id_rateidx] == 0)
  362                         newthr = ra->ra_avg_rssi;
  363                 else
  364                         newthr = (*thrs)[id->id_rateidx];
  365                 (*thrs)[id->id_rateidx + 1] =
  366                     interpolate(master_expavgctl.rc_decay, oldthr, newthr);
  367 
  368                 RSSADAPT_PRINTF(("-> %d\n", (*thrs)[id->id_rateidx + 1]));
  369         }
  370 
  371 #ifdef IEEE80211_DEBUG
  372         if (RSSADAPT_DO_PRINT()) {
  373                 printf("%s: dst %s thresholds\n", ic->ic_if.if_xname,
  374                     ether_sprintf(ni->ni_macaddr));
  375                 for (i = 0; i < IEEE80211_RSSADAPT_BKTS; i++) {
  376                         printf("%d-byte", IEEE80211_RSSADAPT_BKT0 << (IEEE80211_RSSADAPT_BKTPOWER * i));
  377                         for (j = 0; j < rs->rs_nrates; j++) {
  378                                 rate = (rs->rs_rates[j] & IEEE80211_RATE_VAL);
  379                                 printf(", T[%d.%d] = %d", rate / 2,
  380                                     rate * 5 % 10, ra->ra_rate_thresh[i][j]);
  381                         }
  382                         printf("\n");
  383                 }
  384         }
  385 #endif /* IEEE80211_DEBUG */
  386 }

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