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authorThomas Huehn <thomas@net.t-labs.tu-berlin.de>2013-03-04 23:30:03 +0100
committerJohannes Berg <johannes.berg@intel.com>2013-03-06 16:36:08 +0100
commit8f15761197c73e1968777e4b4d968ab0fba2cb74 (patch)
treefbc4072aa6e30a49801b57865f21cc6ede73bee5 /net/mac80211/rc80211_minstrel.c
parentc8ca8c2f933a516b5f4586d7dc6055b72107f246 (diff)
downloadlinux-8f15761197c73e1968777e4b4d968ab0fba2cb74.tar.bz2
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>
Diffstat (limited to 'net/mac80211/rc80211_minstrel.c')
-rw-r--r--net/mac80211/rc80211_minstrel.c81
1 files changed, 49 insertions, 32 deletions
diff --git a/net/mac80211/rc80211_minstrel.c b/net/mac80211/rc80211_minstrel.c
index c9b990237991..152bb0e37865 100644
--- a/net/mac80211/rc80211_minstrel.c
+++ b/net/mac80211/rc80211_minstrel.c
@@ -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++) {