cregit-Linux how code gets into the kernel

Release 4.8 net/mac80211/rc80211_minstrel.c

Directory: net/mac80211
/*
 * 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; }

Contributors

PersonTokensPropCommitsCommitProp
felix fietkaufelix fietkau50100.00%1100.00%
Total50100.00%1100.00%

/* 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)); }

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PersonTokensPropCommitsCommitProp
thomas huehnthomas huehn91100.00%2100.00%
Total91100.00%2100.00%

/* 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; }

Contributors

PersonTokensPropCommitsCommitProp
thomas huehnthomas huehn12679.75%375.00%
adrien schildknechtadrien schildknecht3220.25%125.00%
Total158100.00%4100.00%


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; }

Contributors

PersonTokensPropCommitsCommitProp
felix fietkaufelix fietkau8797.75%266.67%
thomas huehnthomas huehn22.25%133.33%
Total89100.00%3100.00%


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); }

Contributors

PersonTokensPropCommitsCommitProp
felix fietkaufelix fietkau186100.00%1100.00%
Total186100.00%1100.00%

/* * Recalculate statistics and counters of a given rate */
void minstrel_calc_rate_stats(struct minstrel_rate_stats *mrs) { if (unlikely(mrs->attempts > 0)) { mrs->sample_skipped = 0; mrs->cur_prob = MINSTREL_FRAC(mrs->success, mrs->attempts); if (unlikely(!mrs->att_hist)) { mrs->prob_ewma = mrs->cur_prob; } else { /* update exponential weighted moving variance */ mrs->prob_ewmsd = minstrel_ewmsd(mrs->prob_ewmsd, mrs->cur_prob, mrs->prob_ewma, EWMA_LEVEL); /*update exponential weighted moving avarage */ mrs->prob_ewma = minstrel_ewma(mrs->prob_ewma, mrs->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; }

Contributors

PersonTokensPropCommitsCommitProp
thomas huehnthomas huehn159100.00%3100.00%
Total159100.00%3100.00%


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 CONFIG_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); }

Contributors

PersonTokensPropCommitsCommitProp
felix fietkaufelix fietkau16444.09%320.00%
thomas huehnthomas huehn16043.01%1066.67%
lorenzo bianconilorenzo bianconi4712.63%16.67%
stephen hemmingerstephen hemminger10.27%16.67%
Total372100.00%15100.00%


static void minstrel_tx_status(void *priv, struct ieee80211_supported_band *sband, struct ieee80211_sta *sta, void *priv_sta, struct ieee80211_tx_info *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); }

Contributors

PersonTokensPropCommitsCommitProp
felix fietkaufelix fietkau17673.95%228.57%
johannes bergjohannes berg4920.59%228.57%
luciano coelholuciano coelho72.94%114.29%
thomas huehnthomas huehn62.52%228.57%
Total238100.00%7100.00%


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; }

Contributors

PersonTokensPropCommitsCommitProp
felix fietkaufelix fietkau7792.77%360.00%
johannes bergjohannes berg44.82%120.00%
thomas huehnthomas huehn22.41%120.00%
Total83100.00%5100.00%


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; }

Contributors

PersonTokensPropCommitsCommitProp
felix fietkaufelix fietkau7089.74%125.00%
thomas huehnthomas huehn56.41%250.00%
bob copelandbob copeland33.85%125.00%
Total78100.00%4100.00%


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; /* management/no-ack frames do not use rate control */ if (rate_control_send_low(sta, priv_sta, txrc)) return; /* 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 CONFIG_MAC80211_DEBUGFS if (mp->fixed_rate_idx != -1) return; #endif 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); }

Contributors

PersonTokensPropCommitsCommitProp
felix fietkaufelix fietkau34879.82%428.57%
thomas huehnthomas huehn419.40%535.71%
johannes bergjohannes berg265.96%214.29%
lorenzo bianconilorenzo bianconi153.44%17.14%
luis r. rodriguezluis r. rodriguez51.15%17.14%
gabor stefanikgabor stefanik10.23%17.14%
Total436100.00%14100.00%


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); }

Contributors

PersonTokensPropCommitsCommitProp
felix fietkaufelix fietkau6664.71%125.00%
simon wunderlichsimon wunderlich3130.39%125.00%
michal kaziormichal kazior43.92%125.00%
johannes bergjohannes berg10.98%125.00%
Total102100.00%4100.00%


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; } } }

Contributors

PersonTokensPropCommitsCommitProp
felix fietkaufelix fietkau12585.03%125.00%
thomas huehnthomas huehn128.16%250.00%
karl beldankarl beldan106.80%125.00%
Total147100.00%4100.00%


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); }

Contributors

PersonTokensPropCommitsCommitProp
felix fietkaufelix fietkau47475.96%433.33%
simon wunderlichsimon wunderlich6710.74%216.67%
thomas huehnthomas huehn375.93%216.67%
christian lamparterchristian lamparter264.17%18.33%
daniel halperindaniel halperin121.92%18.33%
michal kaziormichal kazior60.96%18.33%
pavel roskinpavel roskin20.32%18.33%
Total624100.00%12100.00%


static void * minstrel_alloc_sta(void *priv, struct ieee80211_sta *sta,