Commit 8f157611 authored by Thomas Huehn's avatar Thomas Huehn Committed by Johannes Berg

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: default avatarFelix Fietkau <nbd@openwrt.org>
Signed-off-by: default avatarThomas Huehn <thomas@net.t-labs.tu-berlin.de>
Signed-off-by: default avatarJohannes Berg <johannes.berg@intel.com>
parent c8ca8c2f
......@@ -78,7 +78,6 @@ minstrel_update_stats(struct minstrel_priv *mp, struct minstrel_sta_info *mi)
u32 usecs;
int i;
mi->stats_update = jiffies;
for (i = 0; i < mi->n_rates; i++) {
struct minstrel_rate *mr = &mi->r[i];
......@@ -144,6 +143,9 @@ minstrel_update_stats(struct minstrel_priv *mp, struct minstrel_sta_info *mi)
mi->max_tp_rate = index_max_tp;
mi->max_tp_rate2 = index_max_tp2;
mi->max_prob_rate = index_max_prob;
/* Reset update timer */
mi->stats_update = jiffies;
}
static void
......@@ -204,10 +206,10 @@ 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;
sample_ndx = SAMPLE_TBL(mi, mi->sample_row, mi->sample_column);
mi->sample_row++;
if ((int) mi->sample_row > (mi->n_rates - 2)) {
mi->sample_row = 0;
mi->sample_column++;
if (mi->sample_column >= SAMPLE_COLUMNS)
mi->sample_column = 0;
......@@ -225,31 +227,37 @@ minstrel_get_rate(void *priv, struct ieee80211_sta *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;
bool mrr_capable;
bool indirect_rate_sampling = false;
bool rate_sampling = false;
int i, delta;
int mrr_ndx[3];
int sample_rate;
int sampling_ratio;
/* management/no-ack frames do not use rate control */
if (rate_control_send_low(sta, priv_sta, txrc))
return;
mrr = mp->has_mrr && !txrc->rts && !txrc->bss_conf->use_cts_prot;
/* 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;
/* init rateindex [ndx] with max throughput rate */
ndx = mi->max_tp_rate;
if (mrr)
sample_rate = mp->lookaround_rate_mrr;
else
sample_rate = mp->lookaround_rate;
/* increase sum packet counter */
mi->packet_count++;
delta = (mi->packet_count * sample_rate / 100) -
delta = (mi->packet_count * sampling_ratio / 100) -
(mi->sample_count + mi->sample_deferred / 2);
/* delta > 0: sampling required */
if ((delta > 0) && (mrr || !mi->prev_sample)) {
if ((delta > 0) && (mrr_capable || !mi->prev_sample)) {
struct minstrel_rate *msr;
if (mi->packet_count >= 10000) {
mi->sample_deferred = 0;
......@@ -268,21 +276,25 @@ minstrel_get_rate(void *priv, struct ieee80211_sta *sta,
mi->sample_count += (delta - mi->n_rates * 2);
}
/* get next random rate sample */
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);
rate_sampling = true;
if (!sample_slower) {
/* Decide if direct ( 1st mrr stage) or indirect (2nd mrr stage)
* rate sampling method should be used */
if (mrr_capable &&
msr->perfect_tx_time > mi->r[ndx].perfect_tx_time)
indirect_rate_sampling = true;
if (!indirect_rate_sampling) {
if (msr->sample_limit != 0) {
ndx = sample_ndx;
mi->sample_count++;
if (msr->sample_limit > 0)
msr->sample_limit--;
} else {
sample = false;
}
} else
rate_sampling = false;
} else {
/* Only use IEEE80211_TX_CTL_RATE_CTRL_PROBE to mark
* packets that have the sampling rate deferred to the
......@@ -294,34 +306,39 @@ minstrel_get_rate(void *priv, struct ieee80211_sta *sta,
mi->sample_deferred++;
}
}
mi->prev_sample = sample;
mi->prev_sample = rate_sampling;
/* 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 > MINSTREL_FRAC(95, 100)))
if (!mrr_capable && rate_sampling &&
(mi->r[ndx].probability > MINSTREL_FRAC(95, 100)))
ndx = mi->max_tp_rate;
/* mrr setup for 1st stage */
ar[0].idx = mi->r[ndx].rix;
ar[0].count = minstrel_get_retry_count(&mi->r[ndx], info);
if (!mrr) {
if (!sample)
/* non mrr setup for 2nd stage */
if (!mrr_capable) {
if (!rate_sampling)
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 setup for 2nd stage */
if (rate_sampling) {
if (indirect_rate_sampling)
mrr_ndx[0] = sample_ndx;
else
mrr_ndx[0] = mi->max_tp_rate;
} else {
mrr_ndx[0] = mi->max_tp_rate2;
}
/* mrr setup for 3rd & 4th stage */
mrr_ndx[1] = mi->max_prob_rate;
mrr_ndx[2] = 0;
for (i = 1; i < 4; i++) {
......@@ -352,7 +369,7 @@ init_sample_table(struct minstrel_sta_info *mi)
u8 rnd[8];
mi->sample_column = 0;
mi->sample_idx = 0;
mi->sample_row = 0;
memset(mi->sample_table, 0, SAMPLE_COLUMNS * mi->n_rates);
for (col = 0; col < SAMPLE_COLUMNS; col++) {
......
......@@ -69,7 +69,7 @@ struct minstrel_sta_info {
unsigned int sample_count;
int sample_deferred;
unsigned int sample_idx;
unsigned int sample_row;
unsigned int sample_column;
int n_rates;
......
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