mac80211: add max lossless throughput per rate

This patch adds the new statistic "maximum possible lossless
throughput" to Minstrels and Minstrel-HTs rc_stats (in debugfs). This
enables comprehensive comparison between current per-rate throughput
and max. achievable per-rate throughput.

Signed-off-by: Thomas Huehn <[e-mail]>
Acked-by: Felix Fietkau <[e-mail]>
Signed-off-by: Johannes Berg <[e-mail]>

net/mac80211/rc80211_minstrel.c

···
 }
 
 /* return current EMWA throughput */
-int minstrel_get_tp_avg(struct minstrel_rate *mr)
+int minstrel_get_tp_avg(struct minstrel_rate *mr, int prob_ewma)
 {
 	int usecs;
 
···
 	/* reset thr. below 10% success */
 	if (mr->stats.prob_ewma < MINSTREL_FRAC(10, 100))
 		return 0;
+
+	if (prob_ewma > MINSTREL_FRAC(90, 100))
+		return MINSTREL_TRUNC(100000 * (MINSTREL_FRAC(90, 100) / usecs));
 	else
-		return MINSTREL_TRUNC(mr->stats.prob_ewma * (100000 / usecs));
+		return MINSTREL_TRUNC(100000 * (prob_ewma / usecs));
 }
 
 /* find & sort topmost throughput rates */
···
 minstrel_sort_best_tp_rates(struct minstrel_sta_info *mi, int i, u8 *tp_list)
 {
 	int j = MAX_THR_RATES;
+	struct minstrel_rate_stats *tmp_mrs = &mi->r[j - 1].stats;
+	struct minstrel_rate_stats *cur_mrs = &mi->r[i].stats;
 
-	while (j > 0 && (minstrel_get_tp_avg(&mi->r[i]) >
-	       minstrel_get_tp_avg(&mi->r[tp_list[j - 1]])))
+	while (j > 0 && (minstrel_get_tp_avg(&mi->r[i], cur_mrs->prob_ewma) >
+	       minstrel_get_tp_avg(&mi->r[tp_list[j - 1]], tmp_mrs->prob_ewma))) {
 		j--;
+		tmp_mrs = &mi->r[tp_list[j - 1]].stats;
+	}
 
 	if (j < MAX_THR_RATES - 1)
 		memmove(&tp_list[j + 1], &tp_list[j], MAX_THR_RATES - (j + 1));
···
 	for (i = 0; i < mi->n_rates; i++) {
 		struct minstrel_rate *mr = &mi->r[i];
 		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 */
 		minstrel_calc_rate_stats(mrs);
···
 		 * (2) if all success probabilities < 95%, the rate with
 		 * highest success probability is chosen as max_prob_rate */
 		if (mrs->prob_ewma >= MINSTREL_FRAC(95, 100)) {
-			tmp_cur_tp = minstrel_get_tp_avg(mr);
-			tmp_prob_tp = minstrel_get_tp_avg(&mi->r[tmp_prob_rate]);
+			tmp_cur_tp = minstrel_get_tp_avg(mr, mrs->prob_ewma);
+			tmp_prob_tp = minstrel_get_tp_avg(&mi->r[tmp_prob_rate],
+							  tmp_mrs->prob_ewma);
 			if (tmp_cur_tp >= tmp_prob_tp)
 				tmp_prob_rate = i;
 		} else {
-			if (mrs->prob_ewma >= mi->r[tmp_prob_rate].stats.prob_ewma)
+			if (mrs->prob_ewma >= tmp_mrs->prob_ewma)
 				tmp_prob_rate = i;
 		}
 	}
···
 static u32 minstrel_get_expected_throughput(void *priv_sta)
 {
 	struct minstrel_sta_info *mi = priv_sta;
+	struct minstrel_rate_stats *tmp_mrs;
 	int idx = mi->max_tp_rate[0];
 	int tmp_cur_tp;
 
 	/* convert pkt per sec in kbps (1200 is the average pkt size used for
 	 * computing cur_tp
 	 */
-	tmp_cur_tp = minstrel_get_tp_avg(&mi->r[idx]);
+	tmp_mrs = &mi->r[idx].stats;
+	tmp_cur_tp = minstrel_get_tp_avg(&mi->r[idx], tmp_mrs->prob_ewma);
 	tmp_cur_tp = tmp_cur_tp * 1200 * 8 / 1024;
 
 	return tmp_cur_tp;

net/mac80211/rc80211_minstrel.h

···
 
 /* Recalculate success probabilities and counters for a given rate using EWMA */
 void minstrel_calc_rate_stats(struct minstrel_rate_stats *mrs);
-int minstrel_get_tp_avg(struct minstrel_rate *mr);
+int minstrel_get_tp_avg(struct minstrel_rate *mr, int prob_ewma);
 
 /* debugfs */
 int minstrel_stats_open(struct inode *inode, struct file *file);

net/mac80211/rc80211_minstrel_debugfs.c

···
 {
 	struct minstrel_sta_info *mi = inode->i_private;
 	struct minstrel_debugfs_info *ms;
-	unsigned int i, tp_avg, prob, eprob;
+	unsigned int i, tp_max, tp_avg, prob, eprob;
 	char *p;
 
 	ms = kmalloc(2048, GFP_KERNEL);
···
 	file->private_data = ms;
 	p = ms->buf;
 	p += sprintf(p, "\n");
-	p += sprintf(p, "best   _______rate_____    __statistics__    "
+	p += sprintf(p, "best   __________rate_________    __statistics__    "
 			"________last_______    ______sum-of________\n");
-	p += sprintf(p, "rate  [name idx airtime]  [ ø(tp) ø(prob)]  "
+	p += sprintf(p, "rate  [name idx airtime max_tp]  [ ø(tp) ø(prob)]  "
 			"[prob.|retry|suc|att]  [#success | #attempts]\n");
 
 	for (i = 0; i < mi->n_rates; i++) {
···
 		p += sprintf(p, " %3u%s ", mr->bitrate / 2,
 				(mr->bitrate & 1 ? ".5" : "  "));
 		p += sprintf(p, "%3u  ", i);
-		p += sprintf(p, "%6u  ", mr->perfect_tx_time);
+		p += sprintf(p, "%6u ", mr->perfect_tx_time);
 
-		tp_avg = minstrel_get_tp_avg(mr);
+		tp_max = minstrel_get_tp_avg(mr, MINSTREL_FRAC(100,100));
+		tp_avg = minstrel_get_tp_avg(mr, mrs->prob_ewma);
 		prob = MINSTREL_TRUNC(mrs->cur_prob * 1000);
 		eprob = MINSTREL_TRUNC(mrs->prob_ewma * 1000);
 
-		p += sprintf(p, " %4u.%1u   %3u.%1u     %3u.%1u %3u"
+		p += sprintf(p, "%4u.%1u   %4u.%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,
 				prob / 10, prob % 10,
···
 {
 	struct minstrel_sta_info *mi = inode->i_private;
 	struct minstrel_debugfs_info *ms;
-	unsigned int i, tp_avg, prob, eprob;
+	unsigned int i, tp_max, tp_avg, prob, eprob;
 	char *p;
 
 	ms = kmalloc(2048, GFP_KERNEL);
···
 		p += sprintf(p, "%u,", i);
 		p += sprintf(p, "%u,",mr->perfect_tx_time);
 
-		tp_avg = minstrel_get_tp_avg(mr);
+		tp_max = minstrel_get_tp_avg(mr, MINSTREL_FRAC(100,100));
+		tp_avg = minstrel_get_tp_avg(mr, mrs->prob_ewma);
 		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,"
+		p += sprintf(p, "%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,
 				prob / 10, prob % 10,

net/mac80211/rc80211_minstrel_ht.c

···
  * account the expected number of retransmissions and their expected length
  */
 int
-minstrel_ht_get_tp_avg(struct minstrel_ht_sta *mi, int group, int rate)
+minstrel_ht_get_tp_avg(struct minstrel_ht_sta *mi, int group, int rate,
+		       int prob_ewma)
 {
-	struct minstrel_rate_stats *mrs;
 	unsigned int nsecs = 0;
-	unsigned int tmp_prob_ewma;
-
-	mrs = &mi->groups[group].rates[rate];
-	tmp_prob_ewma = mrs->prob_ewma;
 
 	/* do not account throughput if sucess prob is below 10% */
-	if (mrs->prob_ewma < MINSTREL_FRAC(10, 100))
+	if (prob_ewma < MINSTREL_FRAC(10, 100))
 		return 0;
-
-	/*
-	 * For the throughput calculation, limit the probability value to 90% to
-	 * account for collision related packet error rate fluctuation
-	 */
-	if (mrs->prob_ewma > MINSTREL_FRAC(90, 100))
-		tmp_prob_ewma = MINSTREL_FRAC(90, 100);
 
 	if (group != MINSTREL_CCK_GROUP)
 		nsecs = 1000 * mi->overhead / MINSTREL_TRUNC(mi->avg_ampdu_len);
 
 	nsecs += minstrel_mcs_groups[group].duration[rate];
 
-	/* prob is scaled - see MINSTREL_FRAC above */
-	return MINSTREL_TRUNC(100000 * ((tmp_prob_ewma * 1000) / nsecs));
+	/*
+	 * For the throughput calculation, limit the probability value to 90% to
+	 * account for collision related packet error rate fluctuation
+	 * (prob is scaled - see MINSTREL_FRAC above)
+	 */
+	if (prob_ewma > MINSTREL_FRAC(90, 100))
+		return MINSTREL_TRUNC(100000 * ((MINSTREL_FRAC(90, 100) * 1000)
+								      / nsecs));
+	else
+		return MINSTREL_TRUNC(100000 * ((prob_ewma * 1000) / nsecs));
 }
 
 /*
···
 
 	cur_group = index / MCS_GROUP_RATES;
 	cur_idx = index  % MCS_GROUP_RATES;
-	cur_tp_avg = minstrel_ht_get_tp_avg(mi, cur_group, cur_idx);
 	cur_prob = mi->groups[cur_group].rates[cur_idx].prob_ewma;
+	cur_tp_avg = minstrel_ht_get_tp_avg(mi, cur_group, cur_idx, cur_prob);
 
 	do {
 		tmp_group = tp_list[j - 1] / MCS_GROUP_RATES;
 		tmp_idx = tp_list[j - 1] % MCS_GROUP_RATES;
-		tmp_tp_avg = minstrel_ht_get_tp_avg(mi, tmp_group, tmp_idx);
 		tmp_prob = mi->groups[tmp_group].rates[tmp_idx].prob_ewma;
+		tmp_tp_avg = minstrel_ht_get_tp_avg(mi, tmp_group, tmp_idx,
+						    tmp_prob);
 		if (cur_tp_avg < tmp_tp_avg ||
 		    (cur_tp_avg == tmp_tp_avg && cur_prob <= tmp_prob))
 			break;
···
 	struct minstrel_rate_stats *mrs;
 	int tmp_group, tmp_idx, tmp_tp_avg, tmp_prob;
 	int max_tp_group, cur_tp_avg, cur_group, cur_idx;
-	int max_group_prob_rate_group, max_group_prob_rate_idx;
-	int max_group_prob_rate_tp_avg;
+	int max_gpr_group, max_gpr_idx;
+	int max_gpr_tp_avg, max_gpr_prob;
 
 	cur_group = index / MCS_GROUP_RATES;
 	cur_idx = index % MCS_GROUP_RATES;
···
 
 	tmp_group = mi->max_prob_rate / MCS_GROUP_RATES;
 	tmp_idx = mi->max_prob_rate % MCS_GROUP_RATES;
-	tmp_tp_avg = minstrel_ht_get_tp_avg(mi, tmp_group, tmp_idx);
 	tmp_prob = mi->groups[tmp_group].rates[tmp_idx].prob_ewma;
+	tmp_tp_avg = minstrel_ht_get_tp_avg(mi, tmp_group, tmp_idx, tmp_prob);
 
 	/* if max_tp_rate[0] is from MCS_GROUP max_prob_rate get selected from
 	 * MCS_GROUP as well as CCK_GROUP rates do not allow aggregation */
···
 		return;
 
 	if (mrs->prob_ewma > MINSTREL_FRAC(75, 100)) {
-		cur_tp_avg = minstrel_ht_get_tp_avg(mi, cur_group, cur_idx);
+		cur_tp_avg = minstrel_ht_get_tp_avg(mi, cur_group, cur_idx,
+						    mrs->prob_ewma);
 		if (cur_tp_avg > tmp_tp_avg)
 			mi->max_prob_rate = index;
 
-		max_group_prob_rate_group = mg->max_group_prob_rate /
-								MCS_GROUP_RATES;
-		max_group_prob_rate_idx = mg->max_group_prob_rate %
-								MCS_GROUP_RATES;
-		max_group_prob_rate_tp_avg = minstrel_ht_get_tp_avg(mi,
-						max_group_prob_rate_group,
-						max_group_prob_rate_idx);
-		if (cur_tp_avg > max_group_prob_rate_tp_avg)
+		max_gpr_group = mg->max_group_prob_rate / MCS_GROUP_RATES;
+		max_gpr_idx = mg->max_group_prob_rate %	MCS_GROUP_RATES;
+		max_gpr_prob = mi->groups[max_gpr_group].rates[max_gpr_idx].prob_ewma;
+		max_gpr_tp_avg = minstrel_ht_get_tp_avg(mi, max_gpr_group,
+							max_gpr_idx,
+							max_gpr_prob);
+		if (cur_tp_avg > max_gpr_tp_avg)
 			mg->max_group_prob_rate = index;
 	} else {
 		if (mrs->prob_ewma > tmp_prob)
···
 				 u16 tmp_mcs_tp_rate[MAX_THR_RATES],
 				 u16 tmp_cck_tp_rate[MAX_THR_RATES])
 {
-	unsigned int tmp_group, tmp_idx, tmp_cck_tp, tmp_mcs_tp;
+	unsigned int tmp_group, tmp_idx, tmp_cck_tp, tmp_mcs_tp, tmp_prob;
 	int i;
 
 	tmp_group = tmp_cck_tp_rate[0] / MCS_GROUP_RATES;
 	tmp_idx = tmp_cck_tp_rate[0] % MCS_GROUP_RATES;
-	tmp_cck_tp = minstrel_ht_get_tp_avg(mi, tmp_group, tmp_idx);
+	tmp_prob = mi->groups[tmp_group].rates[tmp_idx].prob_ewma;
+	tmp_cck_tp = minstrel_ht_get_tp_avg(mi, tmp_group, tmp_idx, tmp_prob);
 
 	tmp_group = tmp_mcs_tp_rate[0] / MCS_GROUP_RATES;
 	tmp_idx = tmp_mcs_tp_rate[0] % MCS_GROUP_RATES;
-	tmp_mcs_tp = minstrel_ht_get_tp_avg(mi, tmp_group, tmp_idx);
+	tmp_prob = mi->groups[tmp_group].rates[tmp_idx].prob_ewma;
+	tmp_mcs_tp = minstrel_ht_get_tp_avg(mi, tmp_group, tmp_idx, tmp_prob);
 
 	if (tmp_cck_tp > tmp_mcs_tp) {
 		for(i = 0; i < MAX_THR_RATES; i++) {
···
 minstrel_ht_prob_rate_reduce_streams(struct minstrel_ht_sta *mi)
 {
 	struct minstrel_mcs_group_data *mg;
-	int tmp_max_streams, group, tmp_idx;
+	int tmp_max_streams, group, tmp_idx, tmp_prob;
 	int tmp_tp = 0;
 
 	tmp_max_streams = minstrel_mcs_groups[mi->max_tp_rate[0] /
···
 			continue;
 
 		tmp_idx = mg->max_group_prob_rate % MCS_GROUP_RATES;
+		tmp_prob = mi->groups[group].rates[tmp_idx].prob_ewma;
 
-		if (tmp_tp < minstrel_ht_get_tp_avg(mi, group, tmp_idx) &&
+		if (tmp_tp < minstrel_ht_get_tp_avg(mi, group, tmp_idx, tmp_prob) &&
 		   (minstrel_mcs_groups[group].streams < tmp_max_streams)) {
 				mi->max_prob_rate = mg->max_group_prob_rate;
 				tmp_tp = minstrel_ht_get_tp_avg(mi, group,
-								tmp_idx);
+								tmp_idx,
+								tmp_prob);
 		}
 	}
 }
···
 {
 	struct minstrel_mcs_group_data *mg;
 	struct minstrel_rate_stats *mrs;
-	int group, i, j;
+	int group, i, j, cur_prob;
 	u16 tmp_mcs_tp_rate[MAX_THR_RATES], tmp_group_tp_rate[MAX_THR_RATES];
 	u16 tmp_cck_tp_rate[MAX_THR_RATES], index;
 
···
 			mrs = &mg->rates[i];
 			mrs->retry_updated = false;
 			minstrel_calc_rate_stats(mrs);
+			cur_prob = mrs->prob_ewma;
 
-			if (minstrel_ht_get_tp_avg(mi, group, i) == 0)
+			if (minstrel_ht_get_tp_avg(mi, group, i, cur_prob) == 0)
 				continue;
 
 			/* Find max throughput rate set */
···
 {
 	struct minstrel_ht_sta_priv *msp = priv_sta;
 	struct minstrel_ht_sta *mi = &msp->ht;
-	int i, j, tp_avg;
+	int i, j, prob, tp_avg;
 
 	if (!msp->is_ht)
 		return mac80211_minstrel.get_expected_throughput(priv_sta);
 
 	i = mi->max_tp_rate[0] / MCS_GROUP_RATES;
 	j = mi->max_tp_rate[0] % MCS_GROUP_RATES;
+	prob = mi->groups[i].rates[j].prob_ewma;
 
 	/* convert tp_avg from pkt per second in kbps */
-	tp_avg = minstrel_ht_get_tp_avg(mi, i, j) * AVG_PKT_SIZE * 8 / 1024;
+	tp_avg = minstrel_ht_get_tp_avg(mi, i, j, prob) * AVG_PKT_SIZE * 8 / 1024;
 
 	return tp_avg;
 }

net/mac80211/rc80211_minstrel_ht.h

···
 
 void minstrel_ht_add_sta_debugfs(void *priv, void *priv_sta, struct dentry *dir);
 void minstrel_ht_remove_sta_debugfs(void *priv, void *priv_sta);
-int minstrel_ht_get_tp_avg(struct minstrel_ht_sta *mi, int group, int rate);
+int minstrel_ht_get_tp_avg(struct minstrel_ht_sta *mi, int group, int rate,
+			   int prob_ewma);
 
 #endif

net/mac80211/rc80211_minstrel_ht_debugfs.c

···
 minstrel_ht_stats_dump(struct minstrel_ht_sta *mi, int i, char *p)
 {
 	const struct mcs_group *mg;
-	unsigned int j, tp_avg, prob, eprob, tx_time;
+	unsigned int j, tp_max, tp_avg, prob, eprob, tx_time;
 	char htmode = '2';
 	char gimode = 'L';
 	u32 gflags;
···
 
 		/* tx_time[rate(i)] in usec */
 		tx_time = DIV_ROUND_CLOSEST(mg->duration[j], 1000);
-		p += sprintf(p, "%6u   ", tx_time);
+		p += sprintf(p, "%6u  ", tx_time);
 
-		tp_avg = minstrel_ht_get_tp_avg(mi, i, j);
+		tp_max = minstrel_ht_get_tp_avg(mi, i, j, MINSTREL_FRAC(100, 100));
+		tp_avg = minstrel_ht_get_tp_avg(mi, i, j, mrs->prob_ewma);
 		prob = MINSTREL_TRUNC(mrs->cur_prob * 1000);
 		eprob = MINSTREL_TRUNC(mrs->prob_ewma * 1000);
 
-		p += sprintf(p, "%4u.%1u   %3u.%1u     %3u.%1u "
+		p += sprintf(p, "%4u.%1u    %4u.%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,
 				prob / 10, prob % 10,
···
 	p = ms->buf;
 
 	p += sprintf(p, "\n");
-	p += sprintf(p, "              best   ________rate______    "
+	p += sprintf(p, "              best   ____________rate__________    "
 			"__statistics__    ________last_______    "
 			"______sum-of________\n");
-	p += sprintf(p, "mode guard #  rate  [name   idx airtime]  [ ø(tp) "
-			"ø(prob)]  [prob.|retry|suc|att]  [#success | "
+	p += sprintf(p, "mode guard #  rate  [name   idx airtime  max_tp]  "
+			"[ ø(tp) ø(prob)]  [prob.|retry|suc|att]  [#success | "
 			"#attempts]\n");
 
 	p = minstrel_ht_stats_dump(mi, MINSTREL_CCK_GROUP, p);
···
 minstrel_ht_stats_csv_dump(struct minstrel_ht_sta *mi, int i, char *p)
 {
 	const struct mcs_group *mg;
-	unsigned int j, tp_avg, prob, eprob, tx_time;
+	unsigned int j, tp_max, tp_avg, prob, eprob, tx_time;
 	char htmode = '2';
 	char gimode = 'L';
 	u32 gflags;
···
 		tx_time = DIV_ROUND_CLOSEST(mg->duration[j], 1000);
 		p += sprintf(p, "%u,", tx_time);
 
-		tp_avg = minstrel_ht_get_tp_avg(mi, i, j);
+		tp_max = minstrel_ht_get_tp_avg(mi, i, j, MINSTREL_FRAC(100, 100));
+		tp_avg = minstrel_ht_get_tp_avg(mi, i, j, mrs->prob_ewma);
 		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,%llu,%llu,",
+		p += sprintf(p, "%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,
 				prob / 10, prob % 10,