588 lines
17 KiB
C
588 lines
17 KiB
C
/*
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* Copyright (C) 2008 Felix Fietkau <nbd@openwrt.org>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* Based on minstrel.c:
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* Copyright (C) 2005-2007 Derek Smithies <derek@indranet.co.nz>
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* Sponsored by Indranet Technologies Ltd
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*
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* Based on sample.c:
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* Copyright (c) 2005 John Bicket
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer,
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* without modification.
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* 2. Redistributions in binary form must reproduce at minimum a disclaimer
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* similar to the "NO WARRANTY" disclaimer below ("Disclaimer") and any
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* redistribution must be conditioned upon including a substantially
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* similar Disclaimer requirement for further binary redistribution.
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* 3. Neither the names of the above-listed copyright holders nor the names
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* of any contributors may be used to endorse or promote products derived
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* from this software without specific prior written permission.
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*
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* Alternatively, this software may be distributed under the terms of the
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* GNU General Public License ("GPL") version 2 as published by the Free
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* Software Foundation.
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*
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* NO WARRANTY
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF NONINFRINGEMENT, MERCHANTIBILITY
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* AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
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* THE COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR SPECIAL, EXEMPLARY,
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* OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER
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* IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
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* THE POSSIBILITY OF SUCH DAMAGES.
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*/
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#include <linux/netdevice.h>
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#include <linux/types.h>
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#include <linux/skbuff.h>
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#include <linux/debugfs.h>
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#include <linux/random.h>
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#include <linux/ieee80211.h>
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#include <linux/slab.h>
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#include <net/mac80211.h>
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#include "rate.h"
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#include "rc80211_minstrel.h"
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#define SAMPLE_TBL(_mi, _idx, _col) \
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_mi->sample_table[(_idx * SAMPLE_COLUMNS) + _col]
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/* convert mac80211 rate index to local array index */
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static inline int
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rix_to_ndx(struct minstrel_sta_info *mi, int rix)
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{
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int i = rix;
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for (i = rix; i >= 0; i--)
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if (mi->r[i].rix == rix)
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break;
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return i;
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}
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/* return current EMWA throughput */
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int minstrel_get_tp_avg(struct minstrel_rate *mr, int prob_ewma)
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{
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int usecs;
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usecs = mr->perfect_tx_time;
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if (!usecs)
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usecs = 1000000;
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/* reset thr. below 10% success */
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if (mr->stats.prob_ewma < MINSTREL_FRAC(10, 100))
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return 0;
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if (prob_ewma > MINSTREL_FRAC(90, 100))
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return MINSTREL_TRUNC(100000 * (MINSTREL_FRAC(90, 100) / usecs));
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else
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return MINSTREL_TRUNC(100000 * (prob_ewma / usecs));
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}
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/* find & sort topmost throughput rates */
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static inline void
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minstrel_sort_best_tp_rates(struct minstrel_sta_info *mi, int i, u8 *tp_list)
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{
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int j;
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struct minstrel_rate_stats *tmp_mrs;
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struct minstrel_rate_stats *cur_mrs = &mi->r[i].stats;
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for (j = MAX_THR_RATES; j > 0; --j) {
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tmp_mrs = &mi->r[tp_list[j - 1]].stats;
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if (minstrel_get_tp_avg(&mi->r[i], cur_mrs->prob_ewma) <=
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minstrel_get_tp_avg(&mi->r[tp_list[j - 1]], tmp_mrs->prob_ewma))
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break;
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}
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if (j < MAX_THR_RATES - 1)
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memmove(&tp_list[j + 1], &tp_list[j], MAX_THR_RATES - (j + 1));
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if (j < MAX_THR_RATES)
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tp_list[j] = i;
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}
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static void
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minstrel_set_rate(struct minstrel_sta_info *mi, struct ieee80211_sta_rates *ratetbl,
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int offset, int idx)
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{
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struct minstrel_rate *r = &mi->r[idx];
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ratetbl->rate[offset].idx = r->rix;
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ratetbl->rate[offset].count = r->adjusted_retry_count;
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ratetbl->rate[offset].count_cts = r->retry_count_cts;
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ratetbl->rate[offset].count_rts = r->stats.retry_count_rtscts;
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}
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static void
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minstrel_update_rates(struct minstrel_priv *mp, struct minstrel_sta_info *mi)
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{
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struct ieee80211_sta_rates *ratetbl;
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int i = 0;
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ratetbl = kzalloc(sizeof(*ratetbl), GFP_ATOMIC);
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if (!ratetbl)
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return;
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/* Start with max_tp_rate */
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minstrel_set_rate(mi, ratetbl, i++, mi->max_tp_rate[0]);
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if (mp->hw->max_rates >= 3) {
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/* At least 3 tx rates supported, use max_tp_rate2 next */
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minstrel_set_rate(mi, ratetbl, i++, mi->max_tp_rate[1]);
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}
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if (mp->hw->max_rates >= 2) {
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/* At least 2 tx rates supported, use max_prob_rate next */
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minstrel_set_rate(mi, ratetbl, i++, mi->max_prob_rate);
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}
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/* Use lowest rate last */
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ratetbl->rate[i].idx = mi->lowest_rix;
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ratetbl->rate[i].count = mp->max_retry;
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ratetbl->rate[i].count_cts = mp->max_retry;
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ratetbl->rate[i].count_rts = mp->max_retry;
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rate_control_set_rates(mp->hw, mi->sta, ratetbl);
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}
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/*
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* Recalculate statistics and counters of a given rate
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*/
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void
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minstrel_calc_rate_stats(struct minstrel_rate_stats *mrs)
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{
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unsigned int cur_prob;
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if (unlikely(mrs->attempts > 0)) {
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mrs->sample_skipped = 0;
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cur_prob = MINSTREL_FRAC(mrs->success, mrs->attempts);
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if (unlikely(!mrs->att_hist)) {
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mrs->prob_ewma = cur_prob;
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} else {
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/*update exponential weighted moving avarage */
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mrs->prob_ewma = minstrel_ewma(mrs->prob_ewma,
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cur_prob,
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EWMA_LEVEL);
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}
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mrs->att_hist += mrs->attempts;
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mrs->succ_hist += mrs->success;
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} else {
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mrs->sample_skipped++;
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}
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mrs->last_success = mrs->success;
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mrs->last_attempts = mrs->attempts;
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mrs->success = 0;
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mrs->attempts = 0;
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}
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static void
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minstrel_update_stats(struct minstrel_priv *mp, struct minstrel_sta_info *mi)
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{
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u8 tmp_tp_rate[MAX_THR_RATES];
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u8 tmp_prob_rate = 0;
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int i, tmp_cur_tp, tmp_prob_tp;
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for (i = 0; i < MAX_THR_RATES; i++)
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tmp_tp_rate[i] = 0;
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for (i = 0; i < mi->n_rates; i++) {
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struct minstrel_rate *mr = &mi->r[i];
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struct minstrel_rate_stats *mrs = &mi->r[i].stats;
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struct minstrel_rate_stats *tmp_mrs = &mi->r[tmp_prob_rate].stats;
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/* Update statistics of success probability per rate */
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minstrel_calc_rate_stats(mrs);
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/* Sample less often below the 10% chance of success.
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* Sample less often above the 95% chance of success. */
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if (mrs->prob_ewma > MINSTREL_FRAC(95, 100) ||
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mrs->prob_ewma < MINSTREL_FRAC(10, 100)) {
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mr->adjusted_retry_count = mrs->retry_count >> 1;
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if (mr->adjusted_retry_count > 2)
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mr->adjusted_retry_count = 2;
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mr->sample_limit = 4;
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} else {
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mr->sample_limit = -1;
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mr->adjusted_retry_count = mrs->retry_count;
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}
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if (!mr->adjusted_retry_count)
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mr->adjusted_retry_count = 2;
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minstrel_sort_best_tp_rates(mi, i, tmp_tp_rate);
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/* To determine the most robust rate (max_prob_rate) used at
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* 3rd mmr stage we distinct between two cases:
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* (1) if any success probabilitiy >= 95%, out of those rates
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* choose the maximum throughput rate as max_prob_rate
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* (2) if all success probabilities < 95%, the rate with
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* highest success probability is chosen as max_prob_rate */
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if (mrs->prob_ewma >= MINSTREL_FRAC(95, 100)) {
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tmp_cur_tp = minstrel_get_tp_avg(mr, mrs->prob_ewma);
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tmp_prob_tp = minstrel_get_tp_avg(&mi->r[tmp_prob_rate],
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tmp_mrs->prob_ewma);
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if (tmp_cur_tp >= tmp_prob_tp)
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tmp_prob_rate = i;
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} else {
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if (mrs->prob_ewma >= tmp_mrs->prob_ewma)
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tmp_prob_rate = i;
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}
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}
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/* Assign the new rate set */
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memcpy(mi->max_tp_rate, tmp_tp_rate, sizeof(mi->max_tp_rate));
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mi->max_prob_rate = tmp_prob_rate;
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#ifdef CONFIG_MAC80211_DEBUGFS
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/* use fixed index if set */
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if (mp->fixed_rate_idx != -1) {
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mi->max_tp_rate[0] = mp->fixed_rate_idx;
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mi->max_tp_rate[1] = mp->fixed_rate_idx;
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mi->max_prob_rate = mp->fixed_rate_idx;
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}
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#endif
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/* Reset update timer */
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mi->last_stats_update = jiffies;
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minstrel_update_rates(mp, mi);
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}
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static void
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minstrel_tx_status(void *priv, struct ieee80211_supported_band *sband,
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void *priv_sta, struct ieee80211_tx_status *st)
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{
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struct ieee80211_tx_info *info = st->info;
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struct minstrel_priv *mp = priv;
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struct minstrel_sta_info *mi = priv_sta;
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struct ieee80211_tx_rate *ar = info->status.rates;
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int i, ndx;
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int success;
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success = !!(info->flags & IEEE80211_TX_STAT_ACK);
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for (i = 0; i < IEEE80211_TX_MAX_RATES; i++) {
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if (ar[i].idx < 0)
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break;
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ndx = rix_to_ndx(mi, ar[i].idx);
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if (ndx < 0)
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continue;
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mi->r[ndx].stats.attempts += ar[i].count;
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if ((i != IEEE80211_TX_MAX_RATES - 1) && (ar[i + 1].idx < 0))
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mi->r[ndx].stats.success += success;
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}
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if ((info->flags & IEEE80211_TX_CTL_RATE_CTRL_PROBE) && (i >= 0))
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mi->sample_packets++;
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if (mi->sample_deferred > 0)
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mi->sample_deferred--;
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if (time_after(jiffies, mi->last_stats_update +
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(mp->update_interval * HZ) / 1000))
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minstrel_update_stats(mp, mi);
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}
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static inline unsigned int
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minstrel_get_retry_count(struct minstrel_rate *mr,
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struct ieee80211_tx_info *info)
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{
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u8 retry = mr->adjusted_retry_count;
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if (info->control.use_rts)
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retry = max_t(u8, 2, min(mr->stats.retry_count_rtscts, retry));
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else if (info->control.use_cts_prot)
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retry = max_t(u8, 2, min(mr->retry_count_cts, retry));
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return retry;
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}
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static int
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minstrel_get_next_sample(struct minstrel_sta_info *mi)
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{
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unsigned int sample_ndx;
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sample_ndx = SAMPLE_TBL(mi, mi->sample_row, mi->sample_column);
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mi->sample_row++;
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if ((int) mi->sample_row >= mi->n_rates) {
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mi->sample_row = 0;
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mi->sample_column++;
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if (mi->sample_column >= SAMPLE_COLUMNS)
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mi->sample_column = 0;
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}
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return sample_ndx;
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}
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static void
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minstrel_get_rate(void *priv, struct ieee80211_sta *sta,
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void *priv_sta, struct ieee80211_tx_rate_control *txrc)
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{
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struct sk_buff *skb = txrc->skb;
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struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
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struct minstrel_sta_info *mi = priv_sta;
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struct minstrel_priv *mp = priv;
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struct ieee80211_tx_rate *rate = &info->control.rates[0];
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struct minstrel_rate *msr, *mr;
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unsigned int ndx;
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bool mrr_capable;
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bool prev_sample;
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int delta;
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int sampling_ratio;
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/* check multi-rate-retry capabilities & adjust lookaround_rate */
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mrr_capable = mp->has_mrr &&
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!txrc->rts &&
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!txrc->bss_conf->use_cts_prot;
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if (mrr_capable)
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sampling_ratio = mp->lookaround_rate_mrr;
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else
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sampling_ratio = mp->lookaround_rate;
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/* increase sum packet counter */
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mi->total_packets++;
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#ifdef CONFIG_MAC80211_DEBUGFS
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if (mp->fixed_rate_idx != -1)
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return;
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#endif
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/* Don't use EAPOL frames for sampling on non-mrr hw */
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if (mp->hw->max_rates == 1 &&
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(info->control.flags & IEEE80211_TX_CTRL_PORT_CTRL_PROTO))
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return;
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delta = (mi->total_packets * sampling_ratio / 100) -
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(mi->sample_packets + mi->sample_deferred / 2);
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/* delta < 0: no sampling required */
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prev_sample = mi->prev_sample;
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mi->prev_sample = false;
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if (delta < 0 || (!mrr_capable && prev_sample))
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return;
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if (mi->total_packets >= 10000) {
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mi->sample_deferred = 0;
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mi->sample_packets = 0;
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mi->total_packets = 0;
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} else if (delta > mi->n_rates * 2) {
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/* With multi-rate retry, not every planned sample
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* attempt actually gets used, due to the way the retry
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* chain is set up - [max_tp,sample,prob,lowest] for
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* sample_rate < max_tp.
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*
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* If there's too much sampling backlog and the link
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* starts getting worse, minstrel would start bursting
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* out lots of sampling frames, which would result
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* in a large throughput loss. */
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mi->sample_packets += (delta - mi->n_rates * 2);
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}
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/* get next random rate sample */
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ndx = minstrel_get_next_sample(mi);
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msr = &mi->r[ndx];
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mr = &mi->r[mi->max_tp_rate[0]];
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/* Decide if direct ( 1st mrr stage) or indirect (2nd mrr stage)
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* rate sampling method should be used.
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* Respect such rates that are not sampled for 20 interations.
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*/
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if (mrr_capable &&
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msr->perfect_tx_time > mr->perfect_tx_time &&
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msr->stats.sample_skipped < 20) {
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/* Only use IEEE80211_TX_CTL_RATE_CTRL_PROBE to mark
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* packets that have the sampling rate deferred to the
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* second MRR stage. Increase the sample counter only
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* if the deferred sample rate was actually used.
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* Use the sample_deferred counter to make sure that
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* the sampling is not done in large bursts */
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info->flags |= IEEE80211_TX_CTL_RATE_CTRL_PROBE;
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rate++;
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mi->sample_deferred++;
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} else {
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if (!msr->sample_limit)
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return;
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mi->sample_packets++;
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if (msr->sample_limit > 0)
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msr->sample_limit--;
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}
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/* If we're not using MRR and the sampling rate already
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* has a probability of >95%, we shouldn't be attempting
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* to use it, as this only wastes precious airtime */
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if (!mrr_capable &&
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(mi->r[ndx].stats.prob_ewma > MINSTREL_FRAC(95, 100)))
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return;
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mi->prev_sample = true;
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rate->idx = mi->r[ndx].rix;
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rate->count = minstrel_get_retry_count(&mi->r[ndx], info);
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}
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static void
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calc_rate_durations(enum nl80211_band band,
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struct minstrel_rate *d,
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struct ieee80211_rate *rate,
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struct cfg80211_chan_def *chandef)
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{
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int erp = !!(rate->flags & IEEE80211_RATE_ERP_G);
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int shift = ieee80211_chandef_get_shift(chandef);
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d->perfect_tx_time = ieee80211_frame_duration(band, 1200,
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DIV_ROUND_UP(rate->bitrate, 1 << shift), erp, 1,
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shift);
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d->ack_time = ieee80211_frame_duration(band, 10,
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DIV_ROUND_UP(rate->bitrate, 1 << shift), erp, 1,
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shift);
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}
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static void
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init_sample_table(struct minstrel_sta_info *mi)
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{
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unsigned int i, col, new_idx;
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u8 rnd[8];
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mi->sample_column = 0;
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mi->sample_row = 0;
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memset(mi->sample_table, 0xff, SAMPLE_COLUMNS * mi->n_rates);
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for (col = 0; col < SAMPLE_COLUMNS; col++) {
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prandom_bytes(rnd, sizeof(rnd));
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for (i = 0; i < mi->n_rates; i++) {
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new_idx = (i + rnd[i & 7]) % mi->n_rates;
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while (SAMPLE_TBL(mi, new_idx, col) != 0xff)
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new_idx = (new_idx + 1) % mi->n_rates;
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SAMPLE_TBL(mi, new_idx, col) = i;
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}
|
|
}
|
|
}
|
|
|
|
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,
|
|
};
|