/* * 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 <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; WARN_ON(mi->r[i].rix != rix); return i; } static inline bool use_low_rate(struct sk_buff *skb) { struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data; struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb); u16 fc; fc = le16_to_cpu(hdr->frame_control); return ((info->flags & IEEE80211_TX_CTL_NO_ACK) || (fc & IEEE80211_FCTL_FTYPE) != IEEE80211_FTYPE_DATA || is_multicast_ether_addr(hdr->addr1)); } 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); 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 (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_supported_band *sband = txrc->sband; 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 (!sta || !mi || use_low_rate(skb)) { ar[0].idx = rate_lowest_index(sband, sta); ar[0].count = mp->max_retry; 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 minstrel_sta_info *mi, 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 minstrel_rate *mr_ctl; unsigned int i, n = 0; unsigned int t_slot = 9; /* FIXME: get real slot time */ mi->lowest_rix = rate_lowest_index(sband, sta); mr_ctl = &mi->r[rix_to_ndx(mi, mi->lowest_rix)]; mi->sp_ack_dur = mr_ctl->ack_time; 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(mi, hw_to_local(mp->hw), 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 + min(cw, mp->cw_max); cw = (cw + 1) << 1; 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[hw->conf.channel->band]; if (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; return mp; } static void minstrel_free(void *priv) { kfree(priv); } static 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); }