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

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

net/mac80211/rc80211_minstrel.c

+49 −32
Original line number Diff line number Diff line
@@ -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;



		/* 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 (!sample_slower) {

		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++) {

net/mac80211/rc80211_minstrel.h

+1 −1
Original line number Diff line number Diff line
@@ -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;