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Diffstat (limited to 'net/mac80211/rc80211_minstrel.c')
| -rw-r--r-- | net/mac80211/rc80211_minstrel.c | 587 |
1 files changed, 587 insertions, 0 deletions
diff --git a/net/mac80211/rc80211_minstrel.c b/net/mac80211/rc80211_minstrel.c new file mode 100644 index 0000000..ceda2e9 --- /dev/null +++ b/net/mac80211/rc80211_minstrel.c @@ -0,0 +1,587 @@ +/* + * Copyright (C) 2008 Felix Fietkau <nbd@openwrt.org> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + * + * Based on minstrel.c: + * Copyright (C) 2005-2007 Derek Smithies <derek@indranet.co.nz> + * Sponsored by Indranet Technologies Ltd + * + * Based on sample.c: + * Copyright (c) 2005 John Bicket + * 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, + * without modification. + * 2. Redistributions in binary form must reproduce at minimum a disclaimer + * similar to the "NO WARRANTY" disclaimer below ("Disclaimer") and any + * redistribution must be conditioned upon including a substantially + * similar Disclaimer requirement for further binary redistribution. + * 3. Neither the names of the above-listed copyright holders nor the names + * of any contributors may be used to endorse or promote products derived + * from this software without specific prior written permission. + * + * Alternatively, this software may be distributed under the terms of the + * GNU General Public License ("GPL") version 2 as published by the Free + * Software Foundation. + * + * NO WARRANTY + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS + * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT + * LIMITED TO, THE IMPLIED WARRANTIES OF NONINFRINGEMENT, MERCHANTIBILITY + * AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL + * THE COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR 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 DAMAGES. + */ +#include <linux/netdevice.h> +#include <linux/types.h> +#include <linux/skbuff.h> +#include <linux/debugfs.h> +#include <linux/random.h> +#include <linux/ieee80211.h> +#include <linux/slab.h> +#include <net/mac80211.h> +#include "rate.h" +#include "rc80211_minstrel.h" + +#define SAMPLE_TBL(_mi, _idx, _col) \ + _mi->sample_table[(_idx * SAMPLE_COLUMNS) + _col] + +/* convert mac80211 rate index to local array index */ +static inline int +rix_to_ndx(struct minstrel_sta_info *mi, int rix) +{ + int i = rix; + for (i = rix; i >= 0; i--) + if (mi->r[i].rix == rix) + break; + return i; +} + +/* return current EMWA throughput */ +int minstrel_get_tp_avg(struct minstrel_rate *mr, int prob_ewma) +{ + int usecs; + + usecs = mr->perfect_tx_time; + if (!usecs) + usecs = 1000000; + + /* reset thr. below 10% success */ + if (mr->stats.prob_ewma < MINSTREL_FRAC(10, 100)) + return 0; + + if (prob_ewma > MINSTREL_FRAC(90, 100)) + return MINSTREL_TRUNC(100000 * (MINSTREL_FRAC(90, 100) / usecs)); + else + return MINSTREL_TRUNC(100000 * (prob_ewma / usecs)); +} + +/* find & sort topmost throughput rates */ +static inline void +minstrel_sort_best_tp_rates(struct minstrel_sta_info *mi, int i, u8 *tp_list) +{ + int j; + struct minstrel_rate_stats *tmp_mrs; + struct minstrel_rate_stats *cur_mrs = &mi->r[i].stats; + + for (j = MAX_THR_RATES; j > 0; --j) { + tmp_mrs = &mi->r[tp_list[j - 1]].stats; + if (minstrel_get_tp_avg(&mi->r[i], cur_mrs->prob_ewma) <= + minstrel_get_tp_avg(&mi->r[tp_list[j - 1]], tmp_mrs->prob_ewma)) + break; + } + + if (j < MAX_THR_RATES - 1) + memmove(&tp_list[j + 1], &tp_list[j], MAX_THR_RATES - (j + 1)); + if (j < MAX_THR_RATES) + tp_list[j] = i; +} + +static void +minstrel_set_rate(struct minstrel_sta_info *mi, struct ieee80211_sta_rates *ratetbl, + int offset, int idx) +{ + struct minstrel_rate *r = &mi->r[idx]; + + ratetbl->rate[offset].idx = r->rix; + ratetbl->rate[offset].count = r->adjusted_retry_count; + ratetbl->rate[offset].count_cts = r->retry_count_cts; + ratetbl->rate[offset].count_rts = r->stats.retry_count_rtscts; +} + +static void +minstrel_update_rates(struct minstrel_priv *mp, struct minstrel_sta_info *mi) +{ + struct ieee80211_sta_rates *ratetbl; + int i = 0; + + ratetbl = kzalloc(sizeof(*ratetbl), GFP_ATOMIC); + if (!ratetbl) + return; + + /* Start with max_tp_rate */ + minstrel_set_rate(mi, ratetbl, i++, mi->max_tp_rate[0]); + + if (mp->hw->max_rates >= 3) { + /* At least 3 tx rates supported, use max_tp_rate2 next */ + minstrel_set_rate(mi, ratetbl, i++, mi->max_tp_rate[1]); + } + + if (mp->hw->max_rates >= 2) { + /* At least 2 tx rates supported, use max_prob_rate next */ + minstrel_set_rate(mi, ratetbl, i++, mi->max_prob_rate); + } + + /* Use lowest rate last */ + ratetbl->rate[i].idx = mi->lowest_rix; + ratetbl->rate[i].count = mp->max_retry; + ratetbl->rate[i].count_cts = mp->max_retry; + ratetbl->rate[i].count_rts = mp->max_retry; + + rate_control_set_rates(mp->hw, mi->sta, ratetbl); +} + +/* +* Recalculate statistics and counters of a given rate +*/ +void +minstrel_calc_rate_stats(struct minstrel_rate_stats *mrs) +{ + unsigned int cur_prob; + + if (unlikely(mrs->attempts > 0)) { + mrs->sample_skipped = 0; + cur_prob = MINSTREL_FRAC(mrs->success, mrs->attempts); + if (unlikely(!mrs->att_hist)) { + mrs->prob_ewma = cur_prob; + } else { + /*update exponential weighted moving avarage */ + mrs->prob_ewma = minstrel_ewma(mrs->prob_ewma, + cur_prob, + EWMA_LEVEL); + } + mrs->att_hist += mrs->attempts; + mrs->succ_hist += mrs->success; + } else { + mrs->sample_skipped++; + } + + mrs->last_success = mrs->success; + mrs->last_attempts = mrs->attempts; + mrs->success = 0; + mrs->attempts = 0; +} + +static void +minstrel_update_stats(struct minstrel_priv *mp, struct minstrel_sta_info *mi) +{ + u8 tmp_tp_rate[MAX_THR_RATES]; + u8 tmp_prob_rate = 0; + int i, tmp_cur_tp, tmp_prob_tp; + + for (i = 0; i < MAX_THR_RATES; i++) + tmp_tp_rate[i] = 0; + + for (i = 0; i < mi->n_rates; i++) { + struct minstrel_rate *mr = &mi->r[i]; + struct minstrel_rate_stats *mrs = &mi->r[i].stats; + struct minstrel_rate_stats *tmp_mrs = &mi->r[tmp_prob_rate].stats; + + /* Update statistics of success probability per rate */ + minstrel_calc_rate_stats(mrs); + + /* Sample less often below the 10% chance of success. + * Sample less often above the 95% chance of success. */ + if (mrs->prob_ewma > MINSTREL_FRAC(95, 100) || + mrs->prob_ewma < MINSTREL_FRAC(10, 100)) { + mr->adjusted_retry_count = mrs->retry_count >> 1; + if (mr->adjusted_retry_count > 2) + mr->adjusted_retry_count = 2; + mr->sample_limit = 4; + } else { + mr->sample_limit = -1; + mr->adjusted_retry_count = mrs->retry_count; + } + if (!mr->adjusted_retry_count) + mr->adjusted_retry_count = 2; + + minstrel_sort_best_tp_rates(mi, i, tmp_tp_rate); + + /* To determine the most robust rate (max_prob_rate) used at + * 3rd mmr stage we distinct between two cases: + * (1) if any success probabilitiy >= 95%, out of those rates + * choose the maximum throughput rate as max_prob_rate + * (2) if all success probabilities < 95%, the rate with + * highest success probability is chosen as max_prob_rate */ + if (mrs->prob_ewma >= MINSTREL_FRAC(95, 100)) { + tmp_cur_tp = minstrel_get_tp_avg(mr, mrs->prob_ewma); + tmp_prob_tp = minstrel_get_tp_avg(&mi->r[tmp_prob_rate], + tmp_mrs->prob_ewma); + if (tmp_cur_tp >= tmp_prob_tp) + tmp_prob_rate = i; + } else { + if (mrs->prob_ewma >= tmp_mrs->prob_ewma) + tmp_prob_rate = i; + } + } + + /* Assign the new rate set */ + memcpy(mi->max_tp_rate, tmp_tp_rate, sizeof(mi->max_tp_rate)); + mi->max_prob_rate = tmp_prob_rate; + +#ifdef CPTCFG_MAC80211_DEBUGFS + /* use fixed index if set */ + if (mp->fixed_rate_idx != -1) { + mi->max_tp_rate[0] = mp->fixed_rate_idx; + mi->max_tp_rate[1] = mp->fixed_rate_idx; + mi->max_prob_rate = mp->fixed_rate_idx; + } +#endif + + /* Reset update timer */ + mi->last_stats_update = jiffies; + + minstrel_update_rates(mp, mi); +} + +static void +minstrel_tx_status(void *priv, struct ieee80211_supported_band *sband, + void *priv_sta, struct ieee80211_tx_status *st) +{ + struct ieee80211_tx_info *info = st->info; + struct minstrel_priv *mp = priv; + struct minstrel_sta_info *mi = priv_sta; + struct ieee80211_tx_rate *ar = info->status.rates; + int i, ndx; + int success; + + success = !!(info->flags & IEEE80211_TX_STAT_ACK); + + for (i = 0; i < IEEE80211_TX_MAX_RATES; i++) { + if (ar[i].idx < 0) + break; + + ndx = rix_to_ndx(mi, ar[i].idx); + if (ndx < 0) + continue; + + mi->r[ndx].stats.attempts += ar[i].count; + + if ((i != IEEE80211_TX_MAX_RATES - 1) && (ar[i + 1].idx < 0)) + mi->r[ndx].stats.success += success; + } + + if ((info->flags & IEEE80211_TX_CTL_RATE_CTRL_PROBE) && (i >= 0)) + mi->sample_packets++; + + if (mi->sample_deferred > 0) + mi->sample_deferred--; + + if (time_after(jiffies, mi->last_stats_update + + (mp->update_interval * HZ) / 1000)) + minstrel_update_stats(mp, mi); +} + + +static inline unsigned int +minstrel_get_retry_count(struct minstrel_rate *mr, + struct ieee80211_tx_info *info) +{ + u8 retry = mr->adjusted_retry_count; + + if (info->control.use_rts) + retry = max_t(u8, 2, min(mr->stats.retry_count_rtscts, retry)); + else if (info->control.use_cts_prot) + retry = max_t(u8, 2, min(mr->retry_count_cts, retry)); + return retry; +} + + +static int +minstrel_get_next_sample(struct minstrel_sta_info *mi) +{ + unsigned int sample_ndx; + sample_ndx = SAMPLE_TBL(mi, mi->sample_row, mi->sample_column); + mi->sample_row++; + if ((int) mi->sample_row >= mi->n_rates) { + mi->sample_row = 0; + mi->sample_column++; + if (mi->sample_column >= SAMPLE_COLUMNS) + mi->sample_column = 0; + } + return sample_ndx; +} + +static void +minstrel_get_rate(void *priv, struct ieee80211_sta *sta, + void *priv_sta, struct ieee80211_tx_rate_control *txrc) +{ + struct sk_buff *skb = txrc->skb; + struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb); + struct minstrel_sta_info *mi = priv_sta; + struct minstrel_priv *mp = priv; + struct ieee80211_tx_rate *rate = &info->control.rates[0]; + struct minstrel_rate *msr, *mr; + unsigned int ndx; + bool mrr_capable; + bool prev_sample; + int delta; + int sampling_ratio; + + /* check multi-rate-retry capabilities & adjust lookaround_rate */ + mrr_capable = mp->has_mrr && + !txrc->rts && + !txrc->bss_conf->use_cts_prot; + if (mrr_capable) + sampling_ratio = mp->lookaround_rate_mrr; + else + sampling_ratio = mp->lookaround_rate; + + /* increase sum packet counter */ + mi->total_packets++; + +#ifdef CPTCFG_MAC80211_DEBUGFS + if (mp->fixed_rate_idx != -1) + return; +#endif + + /* Don't use EAPOL frames for sampling on non-mrr hw */ + if (mp->hw->max_rates == 1 && + (info->control.flags & IEEE80211_TX_CTRL_PORT_CTRL_PROTO)) + return; + + delta = (mi->total_packets * sampling_ratio / 100) - + (mi->sample_packets + mi->sample_deferred / 2); + + /* delta < 0: no sampling required */ + prev_sample = mi->prev_sample; + mi->prev_sample = false; + if (delta < 0 || (!mrr_capable && prev_sample)) + return; + + if (mi->total_packets >= 10000) { + mi->sample_deferred = 0; + mi->sample_packets = 0; + mi->total_packets = 0; + } else if (delta > mi->n_rates * 2) { + /* With multi-rate retry, not every planned sample + * attempt actually gets used, due to the way the retry + * chain is set up - [max_tp,sample,prob,lowest] for + * sample_rate < max_tp. + * + * If there's too much sampling backlog and the link + * starts getting worse, minstrel would start bursting + * out lots of sampling frames, which would result + * in a large throughput loss. */ + mi->sample_packets += (delta - mi->n_rates * 2); + } + + /* get next random rate sample */ + ndx = minstrel_get_next_sample(mi); + msr = &mi->r[ndx]; + mr = &mi->r[mi->max_tp_rate[0]]; + + /* Decide if direct ( 1st mrr stage) or indirect (2nd mrr stage) + * rate sampling method should be used. + * Respect such rates that are not sampled for 20 interations. + */ + if (mrr_capable && + msr->perfect_tx_time > mr->perfect_tx_time && + msr->stats.sample_skipped < 20) { + /* Only use IEEE80211_TX_CTL_RATE_CTRL_PROBE to mark + * packets that have the sampling rate deferred to the + * second MRR stage. Increase the sample counter only + * if the deferred sample rate was actually used. + * Use the sample_deferred counter to make sure that + * the sampling is not done in large bursts */ + info->flags |= IEEE80211_TX_CTL_RATE_CTRL_PROBE; + rate++; + mi->sample_deferred++; + } else { + if (!msr->sample_limit) + return; + + mi->sample_packets++; + if (msr->sample_limit > 0) + msr->sample_limit--; + } + + /* If we're not using MRR and the sampling rate already + * has a probability of >95%, we shouldn't be attempting + * to use it, as this only wastes precious airtime */ + if (!mrr_capable && + (mi->r[ndx].stats.prob_ewma > MINSTREL_FRAC(95, 100))) + return; + + mi->prev_sample = true; + + rate->idx = mi->r[ndx].rix; + rate->count = minstrel_get_retry_count(&mi->r[ndx], info); +} + + +static void +calc_rate_durations(enum nl80211_band band, + struct minstrel_rate *d, + struct ieee80211_rate *rate, + struct cfg80211_chan_def *chandef) +{ + int erp = !!(rate->flags & IEEE80211_RATE_ERP_G); + int shift = ieee80211_chandef_get_shift(chandef); + + d->perfect_tx_time = ieee80211_frame_duration(band, 1200, + DIV_ROUND_UP(rate->bitrate, 1 << shift), erp, 1, + shift); + d->ack_time = ieee80211_frame_duration(band, 10, + DIV_ROUND_UP(rate->bitrate, 1 << shift), erp, 1, + shift); +} + +static void +init_sample_table(struct minstrel_sta_info *mi) +{ + unsigned int i, col, new_idx; + u8 rnd[8]; + + mi->sample_column = 0; + mi->sample_row = 0; + memset(mi->sample_table, 0xff, SAMPLE_COLUMNS * mi->n_rates); + + for (col = 0; col < SAMPLE_COLUMNS; col++) { + prandom_bytes(rnd, sizeof(rnd)); + for (i = 0; i < mi->n_rates; i++) { + new_idx = (i + rnd[i & 7]) % mi->n_rates; + while (SAMPLE_TBL(mi, new_idx, col) != 0xff) + new_idx = (new_idx + 1) % mi->n_rates; + + SAMPLE_TBL(mi, new_idx, col) = i; + } + } +} + +static void +minstrel_rate_init(void *priv, struct ieee80211_supported_band *sband, + struct cfg80211_chan_def *chandef, + struct ieee80211_sta *sta, void *priv_sta) +{ + struct minstrel_sta_info *mi = priv_sta; + struct minstrel_priv *mp = priv; + struct ieee80211_rate *ctl_rate; + unsigned int i, n = 0; + unsigned int t_slot = 9; /* FIXME: get real slot time */ + u32 rate_flags; + + mi->sta = sta; + mi->lowest_rix = rate_lowest_index(sband, sta); + ctl_rate = &sband->bitrates[mi->lowest_rix]; + mi->sp_ack_dur = ieee80211_frame_duration(sband->band, 10, + ctl_rate->bitrate, + !!(ctl_rate->flags & IEEE80211_RATE_ERP_G), 1, + ieee80211_chandef_get_shift(chandef)); + + rate_flags = ieee80211_chandef_rate_flags(&mp->hw->conf.chandef); + memset(mi->max_tp_rate, 0, sizeof(mi->max_tp_rate)); + mi->max_prob_rate = 0; + + for (i = 0; i < sband->n_bitrates; i++) { + struct minstrel_rate *mr = &mi->r[n]; + struct minstrel_rate_stats *mrs = &mi->r[n].stats; + unsigned int tx_time = 0, tx_time_cts = 0, tx_time_rtscts = 0; + unsigned int tx_time_single; + unsigned int cw = mp->cw_min; + int shift; + + if (!rate_supported(sta, sband->band, i)) + continue; + if ((rate_flags & sband->bitrates[i].flags) != rate_flags) + continue; + + n++; + memset(mr, 0, sizeof(*mr)); + memset(mrs, 0, sizeof(*mrs)); + + mr->rix = i; + shift = ieee80211_chandef_get_shift(chandef); + mr->bitrate = DIV_ROUND_UP(sband->bitrates[i].bitrate, + (1 << shift) * 5); + calc_rate_durations(sband->band, mr, &sband->bitrates[i], + chandef); + + /* calculate maximum number of retransmissions before + * fallback (based on maximum segment size) */ + mr->sample_limit = -1; + mrs->retry_count = 1; + mr->retry_count_cts = 1; + mrs->retry_count_rtscts = 1; + tx_time = mr->perfect_tx_time + mi->sp_ack_dur; + do { + /* add one retransmission */ + tx_time_single = mr->ack_time + mr->perfect_tx_time; + + /* contention window */ + tx_time_single += (t_slot * cw) >> 1; + cw = min((cw << 1) | 1, mp->cw_max); + + tx_time += tx_time_single; + tx_time_cts += tx_time_single + mi->sp_ack_dur; + tx_time_rtscts += tx_time_single + 2 * mi->sp_ack_dur; + if ((tx_time_cts < mp->segment_size) && + (mr->retry_count_cts < mp->max_retry)) + mr->retry_count_cts++; + if ((tx_time_rtscts < mp->segment_size) && + (mrs->retry_count_rtscts < mp->max_retry)) + mrs->retry_count_rtscts++; + } while ((tx_time < mp->segment_size) && + (++mr->stats.retry_count < mp->max_retry)); + mr->adjusted_retry_count = mrs->retry_count; + if (!(sband->bitrates[i].flags & IEEE80211_RATE_ERP_G)) + mr->retry_count_cts = mrs->retry_count; + } + + for (i = n; i < sband->n_bitrates; i++) { + struct minstrel_rate *mr = &mi->r[i]; + mr->rix = -1; + } + + mi->n_rates = n; + mi->last_stats_update = jiffies; + + init_sample_table(mi); + minstrel_update_rates(mp, mi); +} + +static u32 minstrel_get_expected_throughput(void *priv_sta) +{ + struct minstrel_sta_info *mi = priv_sta; + struct minstrel_rate_stats *tmp_mrs; + int idx = mi->max_tp_rate[0]; + int tmp_cur_tp; + + /* convert pkt per sec in kbps (1200 is the average pkt size used for + * computing cur_tp + */ + tmp_mrs = &mi->r[idx].stats; + tmp_cur_tp = minstrel_get_tp_avg(&mi->r[idx], tmp_mrs->prob_ewma) * 10; + tmp_cur_tp = tmp_cur_tp * 1200 * 8 / 1024; + + return tmp_cur_tp; +} + +const struct rate_control_ops mac80211_minstrel = { + .tx_status_ext = minstrel_tx_status, + .get_rate = minstrel_get_rate, + .rate_init = minstrel_rate_init, + .get_expected_throughput = minstrel_get_expected_throughput, +}; 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