net/mac80211/rc80211

/* [<][>][^][v][top][bottom][index][help] */
This source file includes following definitions.
rix_to_ndx
minstrel_get_tp_avg
minstrel_sort_best_tp_rates
minstrel_set_rate
minstrel_update_rates
minstrel_calc_rate_stats
minstrel_update_stats
minstrel_tx_status
minstrel_get_retry_count
minstrel_get_next_sample
minstrel_get_rate
calc_rate_durations
init_sample_table
minstrel_rate_init
minstrel_get_expected_throughput
   1 /*
   2  * Copyright (C) 2008 Felix Fietkau <nbd@openwrt.org>
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License version 2 as
   6  * published by the Free Software Foundation.
   7  *
   8  * Based on minstrel.c:
   9  *   Copyright (C) 2005-2007 Derek Smithies <derek@indranet.co.nz>
  10  *   Sponsored by Indranet Technologies Ltd
  11  *
  12  * Based on sample.c:
  13  *   Copyright (c) 2005 John Bicket
  14  *   All rights reserved.
  15  *
  16  *   Redistribution and use in source and binary forms, with or without
  17  *   modification, are permitted provided that the following conditions
  18  *   are met:
  19  *   1. Redistributions of source code must retain the above copyright
  20  *      notice, this list of conditions and the following disclaimer,
  21  *      without modification.
  22  *   2. Redistributions in binary form must reproduce at minimum a disclaimer
  23  *      similar to the "NO WARRANTY" disclaimer below ("Disclaimer") and any
  24  *      redistribution must be conditioned upon including a substantially
  25  *      similar Disclaimer requirement for further binary redistribution.
  26  *   3. Neither the names of the above-listed copyright holders nor the names
  27  *      of any contributors may be used to endorse or promote products derived
  28  *      from this software without specific prior written permission.
  29  *
  30  *   Alternatively, this software may be distributed under the terms of the
  31  *   GNU General Public License ("GPL") version 2 as published by the Free
  32  *   Software Foundation.
  33  *
  34  *   NO WARRANTY
  35  *   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  36  *   ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  37  *   LIMITED TO, THE IMPLIED WARRANTIES OF NONINFRINGEMENT, MERCHANTIBILITY
  38  *   AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
  39  *   THE COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR SPECIAL, EXEMPLARY,
  40  *   OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  41  *   SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  42  *   INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER
  43  *   IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  44  *   ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
  45  *   THE POSSIBILITY OF SUCH DAMAGES.
  46  */
  47 #include <linux/netdevice.h>
  48 #include <linux/types.h>
  49 #include <linux/skbuff.h>
  50 #include <linux/debugfs.h>
  51 #include <linux/random.h>
  52 #include <linux/ieee80211.h>
  53 #include <linux/slab.h>
  54 #include <net/mac80211.h>
  55 #include "rate.h"
  56 #include "rc80211_minstrel.h"
  57 
  58 #define SAMPLE_TBL(_mi, _idx, _col) \
  59                 _mi->sample_table[(_idx * SAMPLE_COLUMNS) + _col]
  60 
  61 /* convert mac80211 rate index to local array index */
  62 static inline int
  63 rix_to_ndx(struct minstrel_sta_info *mi, int rix)
  64 {
  65         int i = rix;
  66         for (i = rix; i >= 0; i--)
  67                 if (mi->r[i].rix == rix)
  68                         break;
  69         return i;
  70 }
  71 
  72 /* return current EMWA throughput */
  73 int minstrel_get_tp_avg(struct minstrel_rate *mr, int prob_ewma)
  74 {
  75         int usecs;
  76 
  77         usecs = mr->perfect_tx_time;
  78         if (!usecs)
  79                 usecs = 1000000;
  80 
  81         /* reset thr. below 10% success */
  82         if (mr->stats.prob_ewma < MINSTREL_FRAC(10, 100))
  83                 return 0;
  84 
  85         if (prob_ewma > MINSTREL_FRAC(90, 100))
  86                 return MINSTREL_TRUNC(100000 * (MINSTREL_FRAC(90, 100) / usecs));
  87         else
  88                 return MINSTREL_TRUNC(100000 * (prob_ewma / usecs));
  89 }
  90 
  91 /* find & sort topmost throughput rates */
  92 static inline void
  93 minstrel_sort_best_tp_rates(struct minstrel_sta_info *mi, int i, u8 *tp_list)
  94 {
  95         int j;
  96         struct minstrel_rate_stats *tmp_mrs;
  97         struct minstrel_rate_stats *cur_mrs = &mi->r[i].stats;
  98 
  99         for (j = MAX_THR_RATES; j > 0; --j) {
 100                 tmp_mrs = &mi->r[tp_list[j - 1]].stats;
 101                 if (minstrel_get_tp_avg(&mi->r[i], cur_mrs->prob_ewma) <=
 102                     minstrel_get_tp_avg(&mi->r[tp_list[j - 1]], tmp_mrs->prob_ewma))
 103                         break;
 104         }
 105 
 106         if (j < MAX_THR_RATES - 1)
 107                 memmove(&tp_list[j + 1], &tp_list[j], MAX_THR_RATES - (j + 1));
 108         if (j < MAX_THR_RATES)
 109                 tp_list[j] = i;
 110 }
 111 
 112 static void
 113 minstrel_set_rate(struct minstrel_sta_info *mi, struct ieee80211_sta_rates *ratetbl,
 114                   int offset, int idx)
 115 {
 116         struct minstrel_rate *r = &mi->r[idx];
 117 
 118         ratetbl->rate[offset].idx = r->rix;
 119         ratetbl->rate[offset].count = r->adjusted_retry_count;
 120         ratetbl->rate[offset].count_cts = r->retry_count_cts;
 121         ratetbl->rate[offset].count_rts = r->stats.retry_count_rtscts;
 122 }
 123 
 124 static void
 125 minstrel_update_rates(struct minstrel_priv *mp, struct minstrel_sta_info *mi)
 126 {
 127         struct ieee80211_sta_rates *ratetbl;
 128         int i = 0;
 129 
 130         ratetbl = kzalloc(sizeof(*ratetbl), GFP_ATOMIC);
 131         if (!ratetbl)
 132                 return;
 133 
 134         /* Start with max_tp_rate */
 135         minstrel_set_rate(mi, ratetbl, i++, mi->max_tp_rate[0]);
 136 
 137         if (mp->hw->max_rates >= 3) {
 138                 /* At least 3 tx rates supported, use max_tp_rate2 next */
 139                 minstrel_set_rate(mi, ratetbl, i++, mi->max_tp_rate[1]);
 140         }
 141 
 142         if (mp->hw->max_rates >= 2) {
 143                 /* At least 2 tx rates supported, use max_prob_rate next */
 144                 minstrel_set_rate(mi, ratetbl, i++, mi->max_prob_rate);
 145         }
 146 
 147         /* Use lowest rate last */
 148         ratetbl->rate[i].idx = mi->lowest_rix;
 149         ratetbl->rate[i].count = mp->max_retry;
 150         ratetbl->rate[i].count_cts = mp->max_retry;
 151         ratetbl->rate[i].count_rts = mp->max_retry;
 152 
 153         rate_control_set_rates(mp->hw, mi->sta, ratetbl);
 154 }
 155 
 156 /*
 157 * Recalculate statistics and counters of a given rate
 158 */
 159 void
 160 minstrel_calc_rate_stats(struct minstrel_rate_stats *mrs)
 161 {
 162         unsigned int cur_prob;
 163 
 164         if (unlikely(mrs->attempts > 0)) {
 165                 mrs->sample_skipped = 0;
 166                 cur_prob = MINSTREL_FRAC(mrs->success, mrs->attempts);
 167                 if (unlikely(!mrs->att_hist)) {
 168                         mrs->prob_ewma = cur_prob;
 169                 } else {
 170                         /*update exponential weighted moving avarage */
 171                         mrs->prob_ewma = minstrel_ewma(mrs->prob_ewma,
 172                                                        cur_prob,
 173                                                        EWMA_LEVEL);
 174                 }
 175                 mrs->att_hist += mrs->attempts;
 176                 mrs->succ_hist += mrs->success;
 177         } else {
 178                 mrs->sample_skipped++;
 179         }
 180 
 181         mrs->last_success = mrs->success;
 182         mrs->last_attempts = mrs->attempts;
 183         mrs->success = 0;
 184         mrs->attempts = 0;
 185 }
 186 
 187 static void
 188 minstrel_update_stats(struct minstrel_priv *mp, struct minstrel_sta_info *mi)
 189 {
 190         u8 tmp_tp_rate[MAX_THR_RATES];
 191         u8 tmp_prob_rate = 0;
 192         int i, tmp_cur_tp, tmp_prob_tp;
 193 
 194         for (i = 0; i < MAX_THR_RATES; i++)
 195             tmp_tp_rate[i] = 0;
 196 
 197         for (i = 0; i < mi->n_rates; i++) {
 198                 struct minstrel_rate *mr = &mi->r[i];
 199                 struct minstrel_rate_stats *mrs = &mi->r[i].stats;
 200                 struct minstrel_rate_stats *tmp_mrs = &mi->r[tmp_prob_rate].stats;
 201 
 202                 /* Update statistics of success probability per rate */
 203                 minstrel_calc_rate_stats(mrs);
 204 
 205                 /* Sample less often below the 10% chance of success.
 206                  * Sample less often above the 95% chance of success. */
 207                 if (mrs->prob_ewma > MINSTREL_FRAC(95, 100) ||
 208                     mrs->prob_ewma < MINSTREL_FRAC(10, 100)) {
 209                         mr->adjusted_retry_count = mrs->retry_count >> 1;
 210                         if (mr->adjusted_retry_count > 2)
 211                                 mr->adjusted_retry_count = 2;
 212                         mr->sample_limit = 4;
 213                 } else {
 214                         mr->sample_limit = -1;
 215                         mr->adjusted_retry_count = mrs->retry_count;
 216                 }
 217                 if (!mr->adjusted_retry_count)
 218                         mr->adjusted_retry_count = 2;
 219 
 220                 minstrel_sort_best_tp_rates(mi, i, tmp_tp_rate);
 221 
 222                 /* To determine the most robust rate (max_prob_rate) used at
 223                  * 3rd mmr stage we distinct between two cases:
 224                  * (1) if any success probabilitiy >= 95%, out of those rates
 225                  * choose the maximum throughput rate as max_prob_rate
 226                  * (2) if all success probabilities < 95%, the rate with
 227                  * highest success probability is chosen as max_prob_rate */
 228                 if (mrs->prob_ewma >= MINSTREL_FRAC(95, 100)) {
 229                         tmp_cur_tp = minstrel_get_tp_avg(mr, mrs->prob_ewma);
 230                         tmp_prob_tp = minstrel_get_tp_avg(&mi->r[tmp_prob_rate],
 231                                                           tmp_mrs->prob_ewma);
 232                         if (tmp_cur_tp >= tmp_prob_tp)
 233                                 tmp_prob_rate = i;
 234                 } else {
 235                         if (mrs->prob_ewma >= tmp_mrs->prob_ewma)
 236                                 tmp_prob_rate = i;
 237                 }
 238         }
 239 
 240         /* Assign the new rate set */
 241         memcpy(mi->max_tp_rate, tmp_tp_rate, sizeof(mi->max_tp_rate));
 242         mi->max_prob_rate = tmp_prob_rate;
 243 
 244 #ifdef CONFIG_MAC80211_DEBUGFS
 245         /* use fixed index if set */
 246         if (mp->fixed_rate_idx != -1) {
 247                 mi->max_tp_rate[0] = mp->fixed_rate_idx;
 248                 mi->max_tp_rate[1] = mp->fixed_rate_idx;
 249                 mi->max_prob_rate = mp->fixed_rate_idx;
 250         }
 251 #endif
 252 
 253         /* Reset update timer */
 254         mi->last_stats_update = jiffies;
 255 
 256         minstrel_update_rates(mp, mi);
 257 }
 258 
 259 static void
 260 minstrel_tx_status(void *priv, struct ieee80211_supported_band *sband,
 261                    void *priv_sta, struct ieee80211_tx_status *st)
 262 {
 263         struct ieee80211_tx_info *info = st->info;
 264         struct minstrel_priv *mp = priv;
 265         struct minstrel_sta_info *mi = priv_sta;
 266         struct ieee80211_tx_rate *ar = info->status.rates;
 267         int i, ndx;
 268         int success;
 269 
 270         success = !!(info->flags & IEEE80211_TX_STAT_ACK);
 271 
 272         for (i = 0; i < IEEE80211_TX_MAX_RATES; i++) {
 273                 if (ar[i].idx < 0)
 274                         break;
 275 
 276                 ndx = rix_to_ndx(mi, ar[i].idx);
 277                 if (ndx < 0)
 278                         continue;
 279 
 280                 mi->r[ndx].stats.attempts += ar[i].count;
 281 
 282                 if ((i != IEEE80211_TX_MAX_RATES - 1) && (ar[i + 1].idx < 0))
 283                         mi->r[ndx].stats.success += success;
 284         }
 285 
 286         if ((info->flags & IEEE80211_TX_CTL_RATE_CTRL_PROBE) && (i >= 0))
 287                 mi->sample_packets++;
 288 
 289         if (mi->sample_deferred > 0)
 290                 mi->sample_deferred--;
 291 
 292         if (time_after(jiffies, mi->last_stats_update +
 293                                 (mp->update_interval * HZ) / 1000))
 294                 minstrel_update_stats(mp, mi);
 295 }
 296 
 297 
 298 static inline unsigned int
 299 minstrel_get_retry_count(struct minstrel_rate *mr,
 300                          struct ieee80211_tx_info *info)
 301 {
 302         u8 retry = mr->adjusted_retry_count;
 303 
 304         if (info->control.use_rts)
 305                 retry = max_t(u8, 2, min(mr->stats.retry_count_rtscts, retry));
 306         else if (info->control.use_cts_prot)
 307                 retry = max_t(u8, 2, min(mr->retry_count_cts, retry));
 308         return retry;
 309 }
 310 
 311 
 312 static int
 313 minstrel_get_next_sample(struct minstrel_sta_info *mi)
 314 {
 315         unsigned int sample_ndx;
 316         sample_ndx = SAMPLE_TBL(mi, mi->sample_row, mi->sample_column);
 317         mi->sample_row++;
 318         if ((int) mi->sample_row >= mi->n_rates) {
 319                 mi->sample_row = 0;
 320                 mi->sample_column++;
 321                 if (mi->sample_column >= SAMPLE_COLUMNS)
 322                         mi->sample_column = 0;
 323         }
 324         return sample_ndx;
 325 }
 326 
 327 static void
 328 minstrel_get_rate(void *priv, struct ieee80211_sta *sta,
 329                   void *priv_sta, struct ieee80211_tx_rate_control *txrc)
 330 {
 331         struct sk_buff *skb = txrc->skb;
 332         struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
 333         struct minstrel_sta_info *mi = priv_sta;
 334         struct minstrel_priv *mp = priv;
 335         struct ieee80211_tx_rate *rate = &info->control.rates[0];
 336         struct minstrel_rate *msr, *mr;
 337         unsigned int ndx;
 338         bool mrr_capable;
 339         bool prev_sample;
 340         int delta;
 341         int sampling_ratio;
 342 
 343         /* check multi-rate-retry capabilities & adjust lookaround_rate */
 344         mrr_capable = mp->has_mrr &&
 345                       !txrc->rts &&
 346                       !txrc->bss_conf->use_cts_prot;
 347         if (mrr_capable)
 348                 sampling_ratio = mp->lookaround_rate_mrr;
 349         else
 350                 sampling_ratio = mp->lookaround_rate;
 351 
 352         /* increase sum packet counter */
 353         mi->total_packets++;
 354 
 355 #ifdef CONFIG_MAC80211_DEBUGFS
 356         if (mp->fixed_rate_idx != -1)
 357                 return;
 358 #endif
 359 
 360         /* Don't use EAPOL frames for sampling on non-mrr hw */
 361         if (mp->hw->max_rates == 1 &&
 362             (info->control.flags & IEEE80211_TX_CTRL_PORT_CTRL_PROTO))
 363                 return;
 364 
 365         delta = (mi->total_packets * sampling_ratio / 100) -
 366                         (mi->sample_packets + mi->sample_deferred / 2);
 367 
 368         /* delta < 0: no sampling required */
 369         prev_sample = mi->prev_sample;
 370         mi->prev_sample = false;
 371         if (delta < 0 || (!mrr_capable && prev_sample))
 372                 return;
 373 
 374         if (mi->total_packets >= 10000) {
 375                 mi->sample_deferred = 0;
 376                 mi->sample_packets = 0;
 377                 mi->total_packets = 0;
 378         } else if (delta > mi->n_rates * 2) {
 379                 /* With multi-rate retry, not every planned sample
 380                  * attempt actually gets used, due to the way the retry
 381                  * chain is set up - [max_tp,sample,prob,lowest] for
 382                  * sample_rate < max_tp.
 383                  *
 384                  * If there's too much sampling backlog and the link
 385                  * starts getting worse, minstrel would start bursting
 386                  * out lots of sampling frames, which would result
 387                  * in a large throughput loss. */
 388                 mi->sample_packets += (delta - mi->n_rates * 2);
 389         }
 390 
 391         /* get next random rate sample */
 392         ndx = minstrel_get_next_sample(mi);
 393         msr = &mi->r[ndx];
 394         mr = &mi->r[mi->max_tp_rate[0]];
 395 
 396         /* Decide if direct ( 1st mrr stage) or indirect (2nd mrr stage)
 397          * rate sampling method should be used.
 398          * Respect such rates that are not sampled for 20 interations.
 399          */
 400         if (mrr_capable &&
 401             msr->perfect_tx_time > mr->perfect_tx_time &&
 402             msr->stats.sample_skipped < 20) {
 403                 /* Only use IEEE80211_TX_CTL_RATE_CTRL_PROBE to mark
 404                  * packets that have the sampling rate deferred to the
 405                  * second MRR stage. Increase the sample counter only
 406                  * if the deferred sample rate was actually used.
 407                  * Use the sample_deferred counter to make sure that
 408                  * the sampling is not done in large bursts */
 409                 info->flags |= IEEE80211_TX_CTL_RATE_CTRL_PROBE;
 410                 rate++;
 411                 mi->sample_deferred++;
 412         } else {
 413                 if (!msr->sample_limit)
 414                         return;
 415 
 416                 mi->sample_packets++;
 417                 if (msr->sample_limit > 0)
 418                         msr->sample_limit--;
 419         }
 420 
 421         /* If we're not using MRR and the sampling rate already
 422          * has a probability of >95%, we shouldn't be attempting
 423          * to use it, as this only wastes precious airtime */
 424         if (!mrr_capable &&
 425            (mi->r[ndx].stats.prob_ewma > MINSTREL_FRAC(95, 100)))
 426                 return;
 427 
 428         mi->prev_sample = true;
 429 
 430         rate->idx = mi->r[ndx].rix;
 431         rate->count = minstrel_get_retry_count(&mi->r[ndx], info);
 432 }
 433 
 434 
 435 static void
 436 calc_rate_durations(enum nl80211_band band,
 437                     struct minstrel_rate *d,
 438                     struct ieee80211_rate *rate,
 439                     struct cfg80211_chan_def *chandef)
 440 {
 441         int erp = !!(rate->flags & IEEE80211_RATE_ERP_G);
 442         int shift = ieee80211_chandef_get_shift(chandef);
 443 
 444         d->perfect_tx_time = ieee80211_frame_duration(band, 1200,
 445                         DIV_ROUND_UP(rate->bitrate, 1 << shift), erp, 1,
 446                         shift);
 447         d->ack_time = ieee80211_frame_duration(band, 10,
 448                         DIV_ROUND_UP(rate->bitrate, 1 << shift), erp, 1,
 449                         shift);
 450 }
 451 
 452 static void
 453 init_sample_table(struct minstrel_sta_info *mi)
 454 {
 455         unsigned int i, col, new_idx;
 456         u8 rnd[8];
 457 
 458         mi->sample_column = 0;
 459         mi->sample_row = 0;
 460         memset(mi->sample_table, 0xff, SAMPLE_COLUMNS * mi->n_rates);
 461 
 462         for (col = 0; col < SAMPLE_COLUMNS; col++) {
 463                 prandom_bytes(rnd, sizeof(rnd));
 464                 for (i = 0; i < mi->n_rates; i++) {
 465                         new_idx = (i + rnd[i & 7]) % mi->n_rates;
 466                         while (SAMPLE_TBL(mi, new_idx, col) != 0xff)
 467                                 new_idx = (new_idx + 1) % mi->n_rates;
 468 
 469                         SAMPLE_TBL(mi, new_idx, col) = i;
 470                 }
 471         }
 472 }
 473 
 474 static void
 475 minstrel_rate_init(void *priv, struct ieee80211_supported_band *sband,
 476                    struct cfg80211_chan_def *chandef,
 477                    struct ieee80211_sta *sta, void *priv_sta)
 478 {
 479         struct minstrel_sta_info *mi = priv_sta;
 480         struct minstrel_priv *mp = priv;
 481         struct ieee80211_rate *ctl_rate;
 482         unsigned int i, n = 0;
 483         unsigned int t_slot = 9; /* FIXME: get real slot time */
 484         u32 rate_flags;
 485 
 486         mi->sta = sta;
 487         mi->lowest_rix = rate_lowest_index(sband, sta);
 488         ctl_rate = &sband->bitrates[mi->lowest_rix];
 489         mi->sp_ack_dur = ieee80211_frame_duration(sband->band, 10,
 490                                 ctl_rate->bitrate,
 491                                 !!(ctl_rate->flags & IEEE80211_RATE_ERP_G), 1,
 492                                 ieee80211_chandef_get_shift(chandef));
 493 
 494         rate_flags = ieee80211_chandef_rate_flags(&mp->hw->conf.chandef);
 495         memset(mi->max_tp_rate, 0, sizeof(mi->max_tp_rate));
 496         mi->max_prob_rate = 0;
 497 
 498         for (i = 0; i < sband->n_bitrates; i++) {
 499                 struct minstrel_rate *mr = &mi->r[n];
 500                 struct minstrel_rate_stats *mrs = &mi->r[n].stats;
 501                 unsigned int tx_time = 0, tx_time_cts = 0, tx_time_rtscts = 0;
 502                 unsigned int tx_time_single;
 503                 unsigned int cw = mp->cw_min;
 504                 int shift;
 505 
 506                 if (!rate_supported(sta, sband->band, i))
 507                         continue;
 508                 if ((rate_flags & sband->bitrates[i].flags) != rate_flags)
 509                         continue;
 510 
 511                 n++;
 512                 memset(mr, 0, sizeof(*mr));
 513                 memset(mrs, 0, sizeof(*mrs));
 514 
 515                 mr->rix = i;
 516                 shift = ieee80211_chandef_get_shift(chandef);
 517                 mr->bitrate = DIV_ROUND_UP(sband->bitrates[i].bitrate,
 518                                            (1 << shift) * 5);
 519                 calc_rate_durations(sband->band, mr, &sband->bitrates[i],
 520                                     chandef);
 521 
 522                 /* calculate maximum number of retransmissions before
 523                  * fallback (based on maximum segment size) */
 524                 mr->sample_limit = -1;
 525                 mrs->retry_count = 1;
 526                 mr->retry_count_cts = 1;
 527                 mrs->retry_count_rtscts = 1;
 528                 tx_time = mr->perfect_tx_time + mi->sp_ack_dur;
 529                 do {
 530                         /* add one retransmission */
 531                         tx_time_single = mr->ack_time + mr->perfect_tx_time;
 532 
 533                         /* contention window */
 534                         tx_time_single += (t_slot * cw) >> 1;
 535                         cw = min((cw << 1) | 1, mp->cw_max);
 536 
 537                         tx_time += tx_time_single;
 538                         tx_time_cts += tx_time_single + mi->sp_ack_dur;
 539                         tx_time_rtscts += tx_time_single + 2 * mi->sp_ack_dur;
 540                         if ((tx_time_cts < mp->segment_size) &&
 541                                 (mr->retry_count_cts < mp->max_retry))
 542                                 mr->retry_count_cts++;
 543                         if ((tx_time_rtscts < mp->segment_size) &&
 544                                 (mrs->retry_count_rtscts < mp->max_retry))
 545                                 mrs->retry_count_rtscts++;
 546                 } while ((tx_time < mp->segment_size) &&
 547                                 (++mr->stats.retry_count < mp->max_retry));
 548                 mr->adjusted_retry_count = mrs->retry_count;
 549                 if (!(sband->bitrates[i].flags & IEEE80211_RATE_ERP_G))
 550                         mr->retry_count_cts = mrs->retry_count;
 551         }
 552 
 553         for (i = n; i < sband->n_bitrates; i++) {
 554                 struct minstrel_rate *mr = &mi->r[i];
 555                 mr->rix = -1;
 556         }
 557 
 558         mi->n_rates = n;
 559         mi->last_stats_update = jiffies;
 560 
 561         init_sample_table(mi);
 562         minstrel_update_rates(mp, mi);
 563 }
 564 
 565 static u32 minstrel_get_expected_throughput(void *priv_sta)
 566 {
 567         struct minstrel_sta_info *mi = priv_sta;
 568         struct minstrel_rate_stats *tmp_mrs;
 569         int idx = mi->max_tp_rate[0];
 570         int tmp_cur_tp;
 571 
 572         /* convert pkt per sec in kbps (1200 is the average pkt size used for
 573          * computing cur_tp
 574          */
 575         tmp_mrs = &mi->r[idx].stats;
 576         tmp_cur_tp = minstrel_get_tp_avg(&mi->r[idx], tmp_mrs->prob_ewma) * 10;
 577         tmp_cur_tp = tmp_cur_tp * 1200 * 8 / 1024;
 578 
 579         return tmp_cur_tp;
 580 }
 581 
 582 const struct rate_control_ops mac80211_minstrel = {
 583         .tx_status_ext = minstrel_tx_status,
 584         .get_rate = minstrel_get_rate,
 585         .rate_init = minstrel_rate_init,
 586         .get_expected_throughput = minstrel_get_expected_throughput,
 587 };
/* [<][>][^][v][top][bottom][index][help] */
root/net/mac80211/rc80211_minstrel.c

DEFINITIONS
