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mac80211: add documentation and verbose variable names in
Add documentation and more verbose variable names to minstrel's multi-rate-retry setup within function minstrel_get_rate() to increase the readability of the algorithm. Acked-by: Felix Fietkau <nbd@openwrt.org> Signed-off-by: Thomas Huehn <thomas@net.t-labs.tu-berlin.de> Signed-off-by: Johannes Berg <johannes.berg@intel.com>
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c8ca8c2f93
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8f15761197
2 changed files with 50 additions and 33 deletions
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@ -78,7 +78,6 @@ minstrel_update_stats(struct minstrel_priv *mp, struct minstrel_sta_info *mi)
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u32 usecs;
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int i;
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mi->stats_update = jiffies;
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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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@ -144,6 +143,9 @@ minstrel_update_stats(struct minstrel_priv *mp, struct minstrel_sta_info *mi)
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mi->max_tp_rate = index_max_tp;
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mi->max_tp_rate2 = index_max_tp2;
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mi->max_prob_rate = index_max_prob;
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/* Reset update timer */
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mi->stats_update = jiffies;
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}
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static void
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@ -204,10 +206,10 @@ 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_idx, mi->sample_column);
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mi->sample_idx++;
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if ((int) mi->sample_idx > (mi->n_rates - 2)) {
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mi->sample_idx = 0;
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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 - 2)) {
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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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@ -225,31 +227,37 @@ minstrel_get_rate(void *priv, struct ieee80211_sta *sta,
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struct minstrel_priv *mp = priv;
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struct ieee80211_tx_rate *ar = info->control.rates;
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unsigned int ndx, sample_ndx = 0;
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bool mrr;
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bool sample_slower = false;
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bool sample = false;
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bool mrr_capable;
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bool indirect_rate_sampling = false;
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bool rate_sampling = false;
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int i, delta;
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int mrr_ndx[3];
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int sample_rate;
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int sampling_ratio;
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/* management/no-ack frames do not use rate control */
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if (rate_control_send_low(sta, priv_sta, txrc))
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return;
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mrr = mp->has_mrr && !txrc->rts && !txrc->bss_conf->use_cts_prot;
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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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/* init rateindex [ndx] with max throughput rate */
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ndx = mi->max_tp_rate;
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if (mrr)
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sample_rate = mp->lookaround_rate_mrr;
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else
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sample_rate = mp->lookaround_rate;
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/* increase sum packet counter */
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mi->packet_count++;
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delta = (mi->packet_count * sample_rate / 100) -
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delta = (mi->packet_count * sampling_ratio / 100) -
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(mi->sample_count + mi->sample_deferred / 2);
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/* delta > 0: sampling required */
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if ((delta > 0) && (mrr || !mi->prev_sample)) {
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if ((delta > 0) && (mrr_capable || !mi->prev_sample)) {
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struct minstrel_rate *msr;
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if (mi->packet_count >= 10000) {
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mi->sample_deferred = 0;
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@ -268,21 +276,25 @@ minstrel_get_rate(void *priv, struct ieee80211_sta *sta,
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mi->sample_count += (delta - mi->n_rates * 2);
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}
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/* get next random rate sample */
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sample_ndx = minstrel_get_next_sample(mi);
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msr = &mi->r[sample_ndx];
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sample = true;
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sample_slower = mrr && (msr->perfect_tx_time >
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mi->r[ndx].perfect_tx_time);
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rate_sampling = true;
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if (!sample_slower) {
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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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if (mrr_capable &&
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msr->perfect_tx_time > mi->r[ndx].perfect_tx_time)
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indirect_rate_sampling = true;
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if (!indirect_rate_sampling) {
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if (msr->sample_limit != 0) {
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ndx = sample_ndx;
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mi->sample_count++;
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if (msr->sample_limit > 0)
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msr->sample_limit--;
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} else {
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sample = false;
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}
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} else
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rate_sampling = false;
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} else {
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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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@ -294,34 +306,39 @@ minstrel_get_rate(void *priv, struct ieee80211_sta *sta,
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mi->sample_deferred++;
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}
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}
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mi->prev_sample = sample;
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mi->prev_sample = rate_sampling;
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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 && sample && (mi->r[ndx].probability > MINSTREL_FRAC(95, 100)))
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if (!mrr_capable && rate_sampling &&
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(mi->r[ndx].probability > MINSTREL_FRAC(95, 100)))
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ndx = mi->max_tp_rate;
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/* mrr setup for 1st stage */
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ar[0].idx = mi->r[ndx].rix;
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ar[0].count = minstrel_get_retry_count(&mi->r[ndx], info);
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if (!mrr) {
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if (!sample)
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/* non mrr setup for 2nd stage */
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if (!mrr_capable) {
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if (!rate_sampling)
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ar[0].count = mp->max_retry;
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ar[1].idx = mi->lowest_rix;
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ar[1].count = mp->max_retry;
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return;
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}
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/* MRR setup */
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if (sample) {
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if (sample_slower)
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/* mrr setup for 2nd stage */
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if (rate_sampling) {
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if (indirect_rate_sampling)
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mrr_ndx[0] = sample_ndx;
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else
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mrr_ndx[0] = mi->max_tp_rate;
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} else {
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mrr_ndx[0] = mi->max_tp_rate2;
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}
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/* mrr setup for 3rd & 4th stage */
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mrr_ndx[1] = mi->max_prob_rate;
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mrr_ndx[2] = 0;
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for (i = 1; i < 4; i++) {
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@ -352,7 +369,7 @@ init_sample_table(struct minstrel_sta_info *mi)
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u8 rnd[8];
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mi->sample_column = 0;
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mi->sample_idx = 0;
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mi->sample_row = 0;
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memset(mi->sample_table, 0, SAMPLE_COLUMNS * mi->n_rates);
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for (col = 0; col < SAMPLE_COLUMNS; col++) {
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@ -69,7 +69,7 @@ struct minstrel_sta_info {
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unsigned int sample_count;
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int sample_deferred;
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unsigned int sample_idx;
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unsigned int sample_row;
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unsigned int sample_column;
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int n_rates;
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