Commit 5f919abc authored by Thomas Huehn's avatar Thomas Huehn Committed by Johannes Berg
Browse files

mac80211: add standard deviation to Minstrel stats 



This patch adds the statistical descriptor "standard deviation"
to better describe the current properties of Minstrel and
Minstrel-HTs success probability distribution. The standard
deviation (SD) is calculated as exponential weighted moving
standard deviation (EWMSD) and its current value is added as
new column in all rc_stats (in debugfs).

Signed-off-by: default avatarThomas Huehn <thomas@net.t-labs.tu-berlin.de>
Acked-by: default avatarFelix Fietkau <nbd@openwrt.org>
Signed-off-by: default avatarJohannes Berg <johannes.berg@intel.com>
parent ade6d4a2

net/mac80211/rc80211_minstrel.c

+14 −5
Original line number Diff line number Diff line
@@ -153,7 +153,7 @@ minstrel_update_rates(struct minstrel_priv *mp, struct minstrel_sta_info *mi) 
}



/*

* Recalculate success probabilities and counters for a given rate using EWMA

* Recalculate statistics and counters of a given rate

*/

void

minstrel_calc_rate_stats(struct minstrel_rate_stats *mrs)
@@ -161,11 +161,20 @@ minstrel_calc_rate_stats(struct minstrel_rate_stats *mrs) 
	if (unlikely(mrs->attempts > 0)) {

		mrs->sample_skipped = 0;

		mrs->cur_prob = MINSTREL_FRAC(mrs->success, mrs->attempts);

		if (unlikely(!mrs->att_hist))

		if (unlikely(!mrs->att_hist)) {

			mrs->prob_ewma = mrs->cur_prob;

		else

		} else {

			/* update exponential weighted moving variance */

			mrs->prob_ewmsd = minstrel_ewmsd(mrs->prob_ewmsd,

							 mrs->cur_prob,

							 mrs->prob_ewma,

							 EWMA_LEVEL);



			/*update exponential weighted moving avarage */

			mrs->prob_ewma = minstrel_ewma(mrs->prob_ewma,

						     mrs->cur_prob, EWMA_LEVEL);

						       mrs->cur_prob,

						       EWMA_LEVEL);

		}

		mrs->att_hist += mrs->attempts;

		mrs->succ_hist += mrs->success;

	} else {
@@ -193,7 +202,7 @@ minstrel_update_stats(struct minstrel_priv *mp, struct minstrel_sta_info *mi) 
		struct minstrel_rate_stats *mrs = &mi->r[i].stats;

		struct minstrel_rate_stats *tmp_mrs = &mi->r[tmp_prob_rate].stats;



		/* Update success probabilities per rate */

		/* Update statistics of success probability per rate */

		minstrel_calc_rate_stats(mrs);



		/* Sample less often below the 10% chance of success.

net/mac80211/rc80211_minstrel.h

+21 −1
Original line number Diff line number Diff line
@@ -35,6 +35,24 @@ minstrel_ewma(int old, int new, int weight) 
	return old + incr;

}



/*

 * Perform EWMSD (Exponentially Weighted Moving Standard Deviation) calculation

 */

static inline int

minstrel_ewmsd(int old_ewmsd, int cur_prob, int prob_ewma, int weight)

{

	int diff, incr, tmp_var;



	/* calculate exponential weighted moving variance */

	diff = MINSTREL_TRUNC((cur_prob - prob_ewma) * 1000000);

	incr = (EWMA_DIV - weight) * diff / EWMA_DIV;

	tmp_var = old_ewmsd * old_ewmsd;

	tmp_var = weight * (tmp_var + diff * incr / 1000000) / EWMA_DIV;



	/* return standard deviation */

	return (u16) int_sqrt(tmp_var);

}



struct minstrel_rate_stats {

	/* current / last sampling period attempts/success counters */

	u16 attempts, last_attempts;
@@ -45,9 +63,11 @@ struct minstrel_rate_stats { 


	/* statistis of packet delivery probability

	 *  cur_prob  - current prob within last update intervall

	 *  prob_ewma - exponential weighted moving average of prob */

	 *  prob_ewma - exponential weighted moving average of prob

	 *  prob_ewmsd - exp. weighted moving standard deviation of prob */

	unsigned int cur_prob;

	unsigned int prob_ewma;

	u16 prob_ewmsd;



	/* maximum retry counts */

	u8 retry_count;

net/mac80211/rc80211_minstrel_debugfs.c

+12 −7
Original line number Diff line number Diff line
@@ -85,10 +85,12 @@ minstrel_stats_open(struct inode *inode, struct file *file) 
	file->private_data = ms;

	p = ms->buf;

	p += sprintf(p, "\n");

	p += sprintf(p, "best   __________rate_________    __statistics__    "

			"________last_______    ______sum-of________\n");

	p += sprintf(p, "rate  [name idx airtime max_tp]  [ ø(tp) ø(prob)]  "

			"[prob.|retry|suc|att]  [#success | #attempts]\n");

	p += sprintf(p, "best   __________rate_________    ______"

			"statistics______    ________last_______    "

			"______sum-of________\n");

	p += sprintf(p, "rate  [name idx airtime max_tp]  [ ø(tp) ø(prob) "

			"sd(prob)]  [prob.|retry|suc|att]  "

			"[#success | #attempts]\n");



	for (i = 0; i < mi->n_rates; i++) {

		struct minstrel_rate *mr = &mi->r[i];
@@ -110,11 +112,13 @@ minstrel_stats_open(struct inode *inode, struct file *file) 
		prob = MINSTREL_TRUNC(mrs->cur_prob * 1000);

		eprob = MINSTREL_TRUNC(mrs->prob_ewma * 1000);



		p += sprintf(p, "%4u.%1u   %4u.%1u   %3u.%1u     %3u.%1u %3u"

				"   %3u %-3u   %9llu   %-9llu\n",

		p += sprintf(p, "%4u.%1u   %4u.%1u   %3u.%1u    %3u.%1u"

				"     %3u.%1u %3u   %3u %-3u   "

				"%9llu   %-9llu\n",

				tp_max / 10, tp_max % 10,

				tp_avg / 10, tp_avg % 10,

				eprob / 10, eprob % 10,

				mrs->prob_ewmsd / 10, mrs->prob_ewmsd % 10,

				prob / 10, prob % 10,

				mrs->retry_count,

				mrs->last_success,
@@ -176,11 +180,12 @@ minstrel_stats_csv_open(struct inode *inode, struct file *file) 
		prob = MINSTREL_TRUNC(mrs->cur_prob * 1000);

		eprob = MINSTREL_TRUNC(mrs->prob_ewma * 1000);



		p += sprintf(p, "%u.%u,%u.%u,%u.%u,%u.%u,%u,%u,%u,"

		p += sprintf(p, "%u.%u,%u.%u,%u.%u,%u.%u,%u.%u,%u,%u,%u,"

				"%llu,%llu,%d,%d\n",

				tp_max / 10, tp_max % 10,

				tp_avg / 10, tp_avg % 10,

				eprob / 10, eprob % 10,

				mrs->prob_ewmsd / 10, mrs->prob_ewmsd % 10,

				prob / 10, prob % 10,

				mrs->retry_count,

				mrs->last_success,

net/mac80211/rc80211_minstrel_ht_debugfs.c

+9 −5
Original line number Diff line number Diff line
@@ -87,10 +87,12 @@ minstrel_ht_stats_dump(struct minstrel_ht_sta *mi, int i, char *p) 
		eprob = MINSTREL_TRUNC(mrs->prob_ewma * 1000);



		p += sprintf(p, "%4u.%1u   %4u.%1u   %3u.%1u    %3u.%1u"

				"%3u   %3u %-3u   %9llu   %-9llu\n",

				"     %3u.%1u %3u   %3u %-3u   "

				"%9llu   %-9llu\n",

				tp_max / 10, tp_max % 10,

				tp_avg / 10, tp_avg % 10,

				eprob / 10, eprob % 10,

				mrs->prob_ewmsd / 10, mrs->prob_ewmsd % 10,

				prob / 10, prob % 10,

				mrs->retry_count,

				mrs->last_success,
@@ -128,10 +130,10 @@ minstrel_ht_stats_open(struct inode *inode, struct file *file) 


	p += sprintf(p, "\n");

	p += sprintf(p, "              best   ____________rate__________    "

			"__statistics__    ________last_______    "

			"______statistics______    ________last_______    "

			"______sum-of________\n");

	p += sprintf(p, "mode guard #  rate  [name   idx airtime  max_tp]  "

			"[ ø(tp) ø(prob)]  [prob.|retry|suc|att]  [#success | "

			"[ ø(tp) ø(prob) sd(prob)]  [prob.|retry|suc|att]  [#success | "

			"#attempts]\n");



	p = minstrel_ht_stats_dump(mi, MINSTREL_CCK_GROUP, p);
@@ -229,10 +231,12 @@ minstrel_ht_stats_csv_dump(struct minstrel_ht_sta *mi, int i, char *p) 
		prob = MINSTREL_TRUNC(mrs->cur_prob * 1000);

		eprob = MINSTREL_TRUNC(mrs->prob_ewma * 1000);



		p += sprintf(p, "%u.%u,%u.%u,%u.%u,%u.%u,%u,%u,%u,%llu,%llu,",

		p += sprintf(p, "%u.%u,%u.%u,%u.%u,%u.%u,%u.%u,%u,%u,"

				"%u,%llu,%llu,",

				tp_max / 10, tp_max % 10,

				tp_avg / 10, tp_avg % 10,

				eprob / 10, eprob % 10,

				mrs->prob_ewmsd / 10, mrs->prob_ewmsd % 10,

				prob / 10, prob % 10,

				mrs->retry_count,

				mrs->last_success,

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