diff options
Diffstat (limited to 'net/mac80211/rc80211_minstrel.c')
| -rw-r--r-- | net/mac80211/rc80211_minstrel.c | 578 |
1 files changed, 578 insertions, 0 deletions
diff --git a/net/mac80211/rc80211_minstrel.c b/net/mac80211/rc80211_minstrel.c new file mode 100644 index 00000000..b39dda52 --- /dev/null +++ b/net/mac80211/rc80211_minstrel.c @@ -0,0 +1,578 @@ +/* + * 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_COLUMNS 10 +#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; +} + +static void +minstrel_update_stats(struct minstrel_priv *mp, struct minstrel_sta_info *mi) +{ + u32 max_tp = 0, index_max_tp = 0, index_max_tp2 = 0; + u32 max_prob = 0, index_max_prob = 0; + u32 usecs; + u32 p; + int i; + + mi->stats_update = jiffies; + for (i = 0; i < mi->n_rates; i++) { + struct minstrel_rate *mr = &mi->r[i]; + + usecs = mr->perfect_tx_time; + if (!usecs) + usecs = 1000000; + + /* To avoid rounding issues, probabilities scale from 0 (0%) + * to 18000 (100%) */ + if (mr->attempts) { + p = (mr->success * 18000) / mr->attempts; + mr->succ_hist += mr->success; + mr->att_hist += mr->attempts; + mr->cur_prob = p; + p = ((p * (100 - mp->ewma_level)) + (mr->probability * + mp->ewma_level)) / 100; + mr->probability = p; + mr->cur_tp = p * (1000000 / usecs); + } + + mr->last_success = mr->success; + mr->last_attempts = mr->attempts; + mr->success = 0; + mr->attempts = 0; + + /* Sample less often below the 10% chance of success. + * Sample less often above the 95% chance of success. */ + if ((mr->probability > 17100) || (mr->probability < 1800)) { + mr->adjusted_retry_count = mr->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 = mr->retry_count; + } + if (!mr->adjusted_retry_count) + mr->adjusted_retry_count = 2; + } + + for (i = 0; i < mi->n_rates; i++) { + struct minstrel_rate *mr = &mi->r[i]; + if (max_tp < mr->cur_tp) { + index_max_tp = i; + max_tp = mr->cur_tp; + } + if (max_prob < mr->probability) { + index_max_prob = i; + max_prob = mr->probability; + } + } + + max_tp = 0; + for (i = 0; i < mi->n_rates; i++) { + struct minstrel_rate *mr = &mi->r[i]; + + if (i == index_max_tp) + continue; + + if (max_tp < mr->cur_tp) { + index_max_tp2 = i; + max_tp = mr->cur_tp; + } + } + mi->max_tp_rate = index_max_tp; + mi->max_tp_rate2 = index_max_tp2; + mi->max_prob_rate = index_max_prob; +} + +static void +minstrel_tx_status(void *priv, struct ieee80211_supported_band *sband, + struct ieee80211_sta *sta, void *priv_sta, + struct sk_buff *skb) +{ + struct minstrel_sta_info *mi = priv_sta; + struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb); + 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].attempts += ar[i].count; + + if ((i != IEEE80211_TX_MAX_RATES - 1) && (ar[i + 1].idx < 0)) + mi->r[ndx].success += success; + } + + if ((info->flags & IEEE80211_TX_CTL_RATE_CTRL_PROBE) && (i >= 0)) + mi->sample_count++; + + if (mi->sample_deferred > 0) + mi->sample_deferred--; +} + + +static inline unsigned int +minstrel_get_retry_count(struct minstrel_rate *mr, + struct ieee80211_tx_info *info) +{ + unsigned int retry = mr->adjusted_retry_count; + + if (info->control.rates[0].flags & IEEE80211_TX_RC_USE_RTS_CTS) + retry = max(2U, min(mr->retry_count_rtscts, retry)); + else if (info->control.rates[0].flags & IEEE80211_TX_RC_USE_CTS_PROTECT) + retry = max(2U, 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_idx, mi->sample_column); + mi->sample_idx++; + if ((int) mi->sample_idx > (mi->n_rates - 2)) { + mi->sample_idx = 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 *ar = info->control.rates; + unsigned int ndx, sample_ndx = 0; + bool mrr; + bool sample_slower = false; + bool sample = false; + int i, delta; + int mrr_ndx[3]; + int sample_rate; + + if (rate_control_send_low(sta, priv_sta, txrc)) + return; + + mrr = mp->has_mrr && !txrc->rts && !txrc->bss_conf->use_cts_prot; + + if (time_after(jiffies, mi->stats_update + (mp->update_interval * + HZ) / 1000)) + minstrel_update_stats(mp, mi); + + ndx = mi->max_tp_rate; + + if (mrr) + sample_rate = mp->lookaround_rate_mrr; + else + sample_rate = mp->lookaround_rate; + + mi->packet_count++; + delta = (mi->packet_count * sample_rate / 100) - + (mi->sample_count + mi->sample_deferred / 2); + + /* delta > 0: sampling required */ + if ((delta > 0) && (mrr || !mi->prev_sample)) { + struct minstrel_rate *msr; + if (mi->packet_count >= 10000) { + mi->sample_deferred = 0; + mi->sample_count = 0; + mi->packet_count = 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_count += (delta - mi->n_rates * 2); + } + + sample_ndx = minstrel_get_next_sample(mi); + msr = &mi->r[sample_ndx]; + sample = true; + sample_slower = mrr && (msr->perfect_tx_time > + mi->r[ndx].perfect_tx_time); + + if (!sample_slower) { + if (msr->sample_limit != 0) { + ndx = sample_ndx; + mi->sample_count++; + if (msr->sample_limit > 0) + msr->sample_limit--; + } else { + sample = false; + } + } else { + /* 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; + mi->sample_deferred++; + } + } + mi->prev_sample = sample; + + /* 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 && sample && (mi->r[ndx].probability > 17100)) + ndx = mi->max_tp_rate; + + ar[0].idx = mi->r[ndx].rix; + ar[0].count = minstrel_get_retry_count(&mi->r[ndx], info); + + if (!mrr) { + if (!sample) + ar[0].count = mp->max_retry; + ar[1].idx = mi->lowest_rix; + ar[1].count = mp->max_retry; + return; + } + + /* MRR setup */ + if (sample) { + if (sample_slower) + mrr_ndx[0] = sample_ndx; + else + mrr_ndx[0] = mi->max_tp_rate; + } else { + mrr_ndx[0] = mi->max_tp_rate2; + } + mrr_ndx[1] = mi->max_prob_rate; + mrr_ndx[2] = 0; + for (i = 1; i < 4; i++) { + ar[i].idx = mi->r[mrr_ndx[i - 1]].rix; + ar[i].count = mi->r[mrr_ndx[i - 1]].adjusted_retry_count; + } +} + + +static void +calc_rate_durations(struct ieee80211_local *local, struct minstrel_rate *d, + struct ieee80211_rate *rate) +{ + int erp = !!(rate->flags & IEEE80211_RATE_ERP_G); + + d->perfect_tx_time = ieee80211_frame_duration(local, 1200, + rate->bitrate, erp, 1); + d->ack_time = ieee80211_frame_duration(local, 10, + rate->bitrate, erp, 1); +} + +static void +init_sample_table(struct minstrel_sta_info *mi) +{ + unsigned int i, col, new_idx; + unsigned int n_srates = mi->n_rates - 1; + u8 rnd[8]; + + mi->sample_column = 0; + mi->sample_idx = 0; + memset(mi->sample_table, 0, SAMPLE_COLUMNS * mi->n_rates); + + for (col = 0; col < SAMPLE_COLUMNS; col++) { + for (i = 0; i < n_srates; i++) { + get_random_bytes(rnd, sizeof(rnd)); + new_idx = (i + rnd[i & 7]) % n_srates; + + while (SAMPLE_TBL(mi, new_idx, col) != 0) + new_idx = (new_idx + 1) % n_srates; + + /* Don't sample the slowest rate (i.e. slowest base + * rate). We must presume that the slowest rate works + * fine, or else other management frames will also be + * failing and the link will break */ + SAMPLE_TBL(mi, new_idx, col) = i + 1; + } + } +} + +static void +minstrel_rate_init(void *priv, struct ieee80211_supported_band *sband, + struct ieee80211_sta *sta, void *priv_sta) +{ + struct minstrel_sta_info *mi = priv_sta; + struct minstrel_priv *mp = priv; + struct ieee80211_local *local = hw_to_local(mp->hw); + struct ieee80211_rate *ctl_rate; + unsigned int i, n = 0; + unsigned int t_slot = 9; /* FIXME: get real slot time */ + + mi->lowest_rix = rate_lowest_index(sband, sta); + ctl_rate = &sband->bitrates[mi->lowest_rix]; + mi->sp_ack_dur = ieee80211_frame_duration(local, 10, ctl_rate->bitrate, + !!(ctl_rate->flags & IEEE80211_RATE_ERP_G), 1); + + for (i = 0; i < sband->n_bitrates; i++) { + struct minstrel_rate *mr = &mi->r[n]; + unsigned int tx_time = 0, tx_time_cts = 0, tx_time_rtscts = 0; + unsigned int tx_time_single; + unsigned int cw = mp->cw_min; + + if (!rate_supported(sta, sband->band, i)) + continue; + n++; + memset(mr, 0, sizeof(*mr)); + + mr->rix = i; + mr->bitrate = sband->bitrates[i].bitrate / 5; + calc_rate_durations(local, mr, &sband->bitrates[i]); + + /* calculate maximum number of retransmissions before + * fallback (based on maximum segment size) */ + mr->sample_limit = -1; + mr->retry_count = 1; + mr->retry_count_cts = 1; + mr->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) && + (mr->retry_count_rtscts < mp->max_retry)) + mr->retry_count_rtscts++; + } while ((tx_time < mp->segment_size) && + (++mr->retry_count < mp->max_retry)); + mr->adjusted_retry_count = mr->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->stats_update = jiffies; + + init_sample_table(mi); +} + +static void * +minstrel_alloc_sta(void *priv, struct ieee80211_sta *sta, gfp_t gfp) +{ + struct ieee80211_supported_band *sband; + struct minstrel_sta_info *mi; + struct minstrel_priv *mp = priv; + struct ieee80211_hw *hw = mp->hw; + int max_rates = 0; + int i; + + mi = kzalloc(sizeof(struct minstrel_sta_info), gfp); + if (!mi) + return NULL; + + for (i = 0; i < IEEE80211_NUM_BANDS; i++) { + sband = hw->wiphy->bands[i]; + if (sband && sband->n_bitrates > max_rates) + max_rates = sband->n_bitrates; + } + + mi->r = kzalloc(sizeof(struct minstrel_rate) * max_rates, gfp); + if (!mi->r) + goto error; + + mi->sample_table = kmalloc(SAMPLE_COLUMNS * max_rates, gfp); + if (!mi->sample_table) + goto error1; + + mi->stats_update = jiffies; + return mi; + +error1: + kfree(mi->r); +error: + kfree(mi); + return NULL; +} + +static void +minstrel_free_sta(void *priv, struct ieee80211_sta *sta, void *priv_sta) +{ + struct minstrel_sta_info *mi = priv_sta; + + kfree(mi->sample_table); + kfree(mi->r); + kfree(mi); +} + +static void * +minstrel_alloc(struct ieee80211_hw *hw, struct dentry *debugfsdir) +{ + struct minstrel_priv *mp; + + mp = kzalloc(sizeof(struct minstrel_priv), GFP_ATOMIC); + if (!mp) + return NULL; + + /* contention window settings + * Just an approximation. Using the per-queue values would complicate + * the calculations and is probably unnecessary */ + mp->cw_min = 15; + mp->cw_max = 1023; + + /* number of packets (in %) to use for sampling other rates + * sample less often for non-mrr packets, because the overhead + * is much higher than with mrr */ + mp->lookaround_rate = 5; + mp->lookaround_rate_mrr = 10; + + /* moving average weight for EWMA */ + mp->ewma_level = 75; + + /* maximum time that the hw is allowed to stay in one MRR segment */ + mp->segment_size = 6000; + + if (hw->max_rate_tries > 0) + mp->max_retry = hw->max_rate_tries; + else + /* safe default, does not necessarily have to match hw properties */ + mp->max_retry = 7; + + if (hw->max_rates >= 4) + mp->has_mrr = true; + + mp->hw = hw; + mp->update_interval = 100; + +#ifdef CONFIG_MAC80211_DEBUGFS + mp->fixed_rate_idx = (u32) -1; + mp->dbg_fixed_rate = debugfs_create_u32("fixed_rate_idx", + S_IRUGO | S_IWUGO, debugfsdir, &mp->fixed_rate_idx); +#endif + + return mp; +} + +static void +minstrel_free(void *priv) +{ +#ifdef CONFIG_MAC80211_DEBUGFS + debugfs_remove(((struct minstrel_priv *)priv)->dbg_fixed_rate); +#endif + kfree(priv); +} + +struct rate_control_ops mac80211_minstrel = { + .name = "minstrel", + .tx_status = minstrel_tx_status, + .get_rate = minstrel_get_rate, + .rate_init = minstrel_rate_init, + .alloc = minstrel_alloc, + .free = minstrel_free, + .alloc_sta = minstrel_alloc_sta, + .free_sta = minstrel_free_sta, +#ifdef CONFIG_MAC80211_DEBUGFS + .add_sta_debugfs = minstrel_add_sta_debugfs, + .remove_sta_debugfs = minstrel_remove_sta_debugfs, +#endif +}; + +int __init +rc80211_minstrel_init(void) +{ + return ieee80211_rate_control_register(&mac80211_minstrel); +} + +void +rc80211_minstrel_exit(void) +{ + ieee80211_rate_control_unregister(&mac80211_minstrel); +} + |