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

     /*      $FreeBSD: releng/8.0/sys/net80211/ieee80211_rssadapt.c 178354 2008-04-20 20:35:46Z sam $        */
     /* $NetBSD: ieee80211_rssadapt.c,v 1.9 2005/02/26 22:45:09 perry Exp $ */
     /*-
      * Copyright (c) 2003, 2004 David Young.  All rights reserved.
      *
      * 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.
     * 3. The name of David Young may not be used to endorse or promote
     *    products derived from this software without specific prior
     *    written permission.
     *
     * THIS SOFTWARE IS PROVIDED BY David Young ``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 David
     * Young 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.
     */
    #include "opt_wlan.h"
    
    #include <sys/param.h>
    #include <sys/kernel.h>
    #include <sys/module.h>
    #include <sys/socket.h>
    #include <sys/sysctl.h>
    
    #include <net/if.h>
    #include <net/if_media.h>
    
    #include <net80211/ieee80211_var.h>
    #include <net80211/ieee80211_rssadapt.h>
    
    struct rssadapt_expavgctl {
            /* RSS threshold decay. */
            u_int rc_decay_denom;
            u_int rc_decay_old;
            /* RSS threshold update. */
            u_int rc_thresh_denom;
            u_int rc_thresh_old;
            /* RSS average update. */
            u_int rc_avgrssi_denom;
            u_int rc_avgrssi_old;
    };
    
    static struct rssadapt_expavgctl master_expavgctl = {
            rc_decay_denom : 16,
            rc_decay_old : 15,
            rc_thresh_denom : 8,
            rc_thresh_old : 4,
            rc_avgrssi_denom : 8,
            rc_avgrssi_old : 4
    };
    
    #ifdef interpolate
    #undef interpolate
    #endif
    #define interpolate(parm, old, new) ((parm##_old * (old) + \
                                         (parm##_denom - parm##_old) * (new)) / \
                                        parm##_denom)
    
    static void rssadapt_sysctlattach(struct ieee80211_rssadapt *rs,
            struct sysctl_ctx_list *ctx, struct sysctl_oid *tree);
    
    /* number of references from net80211 layer */
    static  int nrefs = 0;
    
    void
    ieee80211_rssadapt_setinterval(struct ieee80211_rssadapt *rs, int msecs)
    {
            int t;
    
            if (msecs < 100)
                    msecs = 100;
            t = msecs_to_ticks(msecs);
            rs->interval = (t < 1) ? 1 : t;
    }
    
    void
    ieee80211_rssadapt_init(struct ieee80211_rssadapt *rs, struct ieee80211vap *vap, int interval)
    {
            rs->vap = vap;
            ieee80211_rssadapt_setinterval(rs, interval);
    
            rssadapt_sysctlattach(rs, vap->iv_sysctl, vap->iv_oid);
    }
    
   void
   ieee80211_rssadapt_cleanup(struct ieee80211_rssadapt *rs)
   {
   }
   
   static void
   rssadapt_updatestats(struct ieee80211_rssadapt_node *ra)
   {
           long interval;
   
           ra->ra_pktrate = (ra->ra_pktrate + 10*(ra->ra_nfail + ra->ra_nok))/2;
           ra->ra_nfail = ra->ra_nok = 0;
   
           /*
            * A node is eligible for its rate to be raised every 1/10 to 10
            * seconds, more eligible in proportion to recent packet rates.
            */
           interval = MAX(10*1000, 10*1000 / MAX(1, 10 * ra->ra_pktrate));
           ra->ra_raise_interval = msecs_to_ticks(interval);
   }
   
   void
   ieee80211_rssadapt_node_init(struct ieee80211_rssadapt *rsa,
       struct ieee80211_rssadapt_node *ra, struct ieee80211_node *ni)
   {
           const struct ieee80211_rateset *rs = &ni->ni_rates;
   
           ra->ra_rs = rsa;
           ra->ra_rates = *rs;
           rssadapt_updatestats(ra);
   
           /* pick initial rate */
           for (ra->ra_rix = rs->rs_nrates - 1;
                ra->ra_rix > 0 && (rs->rs_rates[ra->ra_rix] & IEEE80211_RATE_VAL) > 72;
                ra->ra_rix--)
                   ;
           ni->ni_txrate = rs->rs_rates[ra->ra_rix] & IEEE80211_RATE_VAL;
           ra->ra_ticks = ticks;
   
           IEEE80211_NOTE(ni->ni_vap, IEEE80211_MSG_RATECTL, ni,
               "RSSADAPT initial rate %d", ni->ni_txrate);
   }
   
   static __inline int
   bucket(int pktlen)
   {
           int i, top, thridx;
   
           for (i = 0, top = IEEE80211_RSSADAPT_BKT0;
                i < IEEE80211_RSSADAPT_BKTS;
                i++, top <<= IEEE80211_RSSADAPT_BKTPOWER) {
                   thridx = i;
                   if (pktlen <= top)
                           break;
           }
           return thridx;
   }
   
   int
   ieee80211_rssadapt_choose(struct ieee80211_node *ni,
       struct ieee80211_rssadapt_node *ra, u_int pktlen)
   {
           const struct ieee80211_rateset *rs = &ra->ra_rates;
           uint16_t (*thrs)[IEEE80211_RATE_SIZE];
           int rix, rssi;
   
           if ((ticks - ra->ra_ticks) > ra->ra_rs->interval) {
                   rssadapt_updatestats(ra);
                   ra->ra_ticks = ticks;
           }
   
           thrs = &ra->ra_rate_thresh[bucket(pktlen)];
   
           /* XXX this is average rssi, should be using last value */
           rssi = ni->ni_ic->ic_node_getrssi(ni);
           for (rix = rs->rs_nrates-1; rix >= 0; rix--)
                   if ((*thrs)[rix] < (rssi << 8))
                           break;
           if (rix != ra->ra_rix) {
                   /* update public rate */
                   ni->ni_txrate = ni->ni_rates.rs_rates[rix] & IEEE80211_RATE_VAL;
                   ra->ra_rix = rix;
   
                   IEEE80211_NOTE(ni->ni_vap, IEEE80211_MSG_RATECTL, ni,
                       "RSSADAPT new rate %d (pktlen %d rssi %d)",
                       ni->ni_txrate, pktlen, rssi);
           }
           return rix;
   }
   
   /*
    * Adapt the data rate to suit the conditions.  When a transmitted
    * packet is dropped after RAL_RSSADAPT_RETRY_LIMIT retransmissions,
    * raise the RSS threshold for transmitting packets of similar length at
    * the same data rate.
    */
   void
   ieee80211_rssadapt_lower_rate(struct ieee80211_rssadapt_node *ra,
       int pktlen, int rssi)
   {
           uint16_t last_thr;
           uint16_t (*thrs)[IEEE80211_RATE_SIZE];
           u_int rix;
   
           thrs = &ra->ra_rate_thresh[bucket(pktlen)];
   
           rix = ra->ra_rix;
           last_thr = (*thrs)[rix];
           (*thrs)[rix] = interpolate(master_expavgctl.rc_thresh,
               last_thr, (rssi << 8));
   
           IEEE80211_DPRINTF(ra->ra_rs->vap, IEEE80211_MSG_RATECTL,
               "RSSADAPT lower threshold for rate %d (last_thr %d new thr %d rssi %d)\n",
               ra->ra_rates.rs_rates[rix + 1] & IEEE80211_RATE_VAL,
               last_thr, (*thrs)[rix], rssi);
   }
   
   void
   ieee80211_rssadapt_raise_rate(struct ieee80211_rssadapt_node *ra,
       int pktlen, int rssi)
   {
           uint16_t (*thrs)[IEEE80211_RATE_SIZE];
           uint16_t newthr, oldthr;
           int rix;
   
           thrs = &ra->ra_rate_thresh[bucket(pktlen)];
   
           rix = ra->ra_rix;
           if ((*thrs)[rix + 1] > (*thrs)[rix]) {
                   oldthr = (*thrs)[rix + 1];
                   if ((*thrs)[rix] == 0)
                           newthr = (rssi << 8);
                   else
                           newthr = (*thrs)[rix];
                   (*thrs)[rix + 1] = interpolate(master_expavgctl.rc_decay,
                       oldthr, newthr);
   
                   IEEE80211_DPRINTF(ra->ra_rs->vap, IEEE80211_MSG_RATECTL,
                       "RSSADAPT raise threshold for rate %d (oldthr %d newthr %d rssi %d)\n",
                       ra->ra_rates.rs_rates[rix + 1] & IEEE80211_RATE_VAL,
                       oldthr, newthr, rssi);
   
                   ra->ra_last_raise = ticks;
           }
   }
   
   static int
   rssadapt_sysctl_interval(SYSCTL_HANDLER_ARGS)
   {
           struct ieee80211_rssadapt *rs = arg1;
           int msecs = ticks_to_msecs(rs->interval);
           int error;
   
           error = sysctl_handle_int(oidp, &msecs, 0, req);
           if (error || !req->newptr)
                   return error;
           ieee80211_rssadapt_setinterval(rs, msecs);
           return 0;
   }
   
   static void
   rssadapt_sysctlattach(struct ieee80211_rssadapt *rs,
       struct sysctl_ctx_list *ctx, struct sysctl_oid *tree)
   {
   
           SYSCTL_ADD_PROC(ctx, SYSCTL_CHILDREN(tree), OID_AUTO,
               "rssadapt_rate_interval", CTLTYPE_INT | CTLFLAG_RW, rs,
               0, rssadapt_sysctl_interval, "I", "rssadapt operation interval (ms)");
   }
   
   /*
    * Module glue.
    */
   IEEE80211_RATE_MODULE(rssadapt, 1);

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