[PATCH 1/6] mac80211: minstrel_ht: use bitfields to encode rate indexes

[PATCH 1/6] mac80211: minstrel_ht: use bitfields to encode rate indexes

[Felix Fietkau]

Get rid of a lot of divisions and modulo operations
Reduces code size and improves performance

Signed-off-by: Felix Fietkau <nbd@nbd.name>
---
 net/mac80211/rc80211_minstrel_ht.c         | 123 +++++++++++----------
 net/mac80211/rc80211_minstrel_ht.h         |  13 +++
 net/mac80211/rc80211_minstrel_ht_debugfs.c |   4 +-
 3 files changed, 78 insertions(+), 62 deletions(-)

diff --git a/net/mac80211/rc80211_minstrel_ht.c b/net/mac80211/rc80211_minstrel_ht.c
index e35948f4e1bf..a3b86fd300f0 100644
--- a/net/mac80211/rc80211_minstrel_ht.c
+++ b/net/mac80211/rc80211_minstrel_ht.c
@@ -379,13 +379,13 @@ minstrel_ht_get_stats(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
 static inline struct minstrel_rate_stats *
 minstrel_get_ratestats(struct minstrel_ht_sta *mi, int index)
 {
-	return &mi->groups[index / MCS_GROUP_RATES].rates[index % MCS_GROUP_RATES];
+	return &mi->groups[MI_RATE_GROUP(index)].rates[MI_RATE_IDX(index)];
 }
 
 static inline int minstrel_get_duration(int index)
 {
-	const struct mcs_group *group = &minstrel_mcs_groups[index / MCS_GROUP_RATES];
-	unsigned int duration = group->duration[index % MCS_GROUP_RATES];
+	const struct mcs_group *group = &minstrel_mcs_groups[MI_RATE_GROUP(index)];
+	unsigned int duration = group->duration[MI_RATE_IDX(index)];
 
 	return duration << group->shift;
 }
@@ -398,7 +398,7 @@ minstrel_ht_avg_ampdu_len(struct minstrel_ht_sta *mi)
 	if (mi->avg_ampdu_len)
 		return MINSTREL_TRUNC(mi->avg_ampdu_len);
 
-	if (minstrel_ht_is_legacy_group(mi->max_tp_rate[0] / MCS_GROUP_RATES))
+	if (minstrel_ht_is_legacy_group(MI_RATE_GROUP(mi->max_tp_rate[0])))
 		return 1;
 
 	duration = minstrel_get_duration(mi->max_tp_rate[0]);
@@ -465,14 +465,14 @@ minstrel_ht_sort_best_tp_rates(struct minstrel_ht_sta *mi, u16 index,
 	int tmp_group, tmp_idx, tmp_tp_avg, tmp_prob;
 	int j = MAX_THR_RATES;
 
-	cur_group = index / MCS_GROUP_RATES;
-	cur_idx = index  % MCS_GROUP_RATES;
+	cur_group = MI_RATE_GROUP(index);
+	cur_idx = MI_RATE_IDX(index);
 	cur_prob = mi->groups[cur_group].rates[cur_idx].prob_avg;
 	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_group = MI_RATE_GROUP(tp_list[j - 1]);
+		tmp_idx = MI_RATE_IDX(tp_list[j - 1]);
 		tmp_prob = mi->groups[tmp_group].rates[tmp_idx].prob_avg;
 		tmp_tp_avg = minstrel_ht_get_tp_avg(mi, tmp_group, tmp_idx,
 						    tmp_prob);
@@ -504,23 +504,23 @@ minstrel_ht_set_best_prob_rate(struct minstrel_ht_sta *mi, u16 *dest, u16 index)
 	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;
-	mg = &mi->groups[index / MCS_GROUP_RATES];
-	mrs = &mg->rates[index % MCS_GROUP_RATES];
+	cur_group = MI_RATE_GROUP(index);
+	cur_idx = MI_RATE_IDX(index);
+	mg = &mi->groups[cur_group];
+	mrs = &mg->rates[cur_idx];
 
-	tmp_group = *dest / MCS_GROUP_RATES;
-	tmp_idx = *dest % MCS_GROUP_RATES;
+	tmp_group = MI_RATE_GROUP(*dest);
+	tmp_idx = MI_RATE_IDX(*dest);
 	tmp_prob = mi->groups[tmp_group].rates[tmp_idx].prob_avg;
 	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 */
-	max_tp_group = mi->max_tp_rate[0] / MCS_GROUP_RATES;
-	max_tp_idx = mi->max_tp_rate[0] % MCS_GROUP_RATES;
+	max_tp_group = MI_RATE_GROUP(mi->max_tp_rate[0]);
+	max_tp_idx = MI_RATE_IDX(mi->max_tp_rate[0]);
 	max_tp_prob = mi->groups[max_tp_group].rates[max_tp_idx].prob_avg;
 
-	if (minstrel_ht_is_legacy_group(index / MCS_GROUP_RATES) &&
+	if (minstrel_ht_is_legacy_group(MI_RATE_GROUP(index)) &&
 	    !minstrel_ht_is_legacy_group(max_tp_group))
 		return;
 
@@ -529,8 +529,8 @@ minstrel_ht_set_best_prob_rate(struct minstrel_ht_sta *mi, u16 *dest, u16 index)
 	    mrs->prob_avg < max_tp_prob)
 		return;
 
-	max_gpr_group = mg->max_group_prob_rate / MCS_GROUP_RATES;
-	max_gpr_idx = mg->max_group_prob_rate % MCS_GROUP_RATES;
+	max_gpr_group = MI_RATE_GROUP(mg->max_group_prob_rate);
+	max_gpr_idx = MI_RATE_IDX(mg->max_group_prob_rate);
 	max_gpr_prob = mi->groups[max_gpr_group].rates[max_gpr_idx].prob_avg;
 
 	if (mrs->prob_avg > MINSTREL_FRAC(75, 100)) {
@@ -567,13 +567,13 @@ minstrel_ht_assign_best_tp_rates(struct minstrel_ht_sta *mi,
 	unsigned int tmp_group, tmp_idx, tmp_cck_tp, tmp_mcs_tp, tmp_prob;
 	int i;
 
-	tmp_group = tmp_legacy_tp_rate[0] / MCS_GROUP_RATES;
-	tmp_idx = tmp_legacy_tp_rate[0] % MCS_GROUP_RATES;
+	tmp_group = MI_RATE_GROUP(tmp_legacy_tp_rate[0]);
+	tmp_idx = MI_RATE_IDX(tmp_legacy_tp_rate[0]);
 	tmp_prob = mi->groups[tmp_group].rates[tmp_idx].prob_avg;
 	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_group = MI_RATE_GROUP(tmp_mcs_tp_rate[0]);
+	tmp_idx = MI_RATE_IDX(tmp_mcs_tp_rate[0]);
 	tmp_prob = mi->groups[tmp_group].rates[tmp_idx].prob_avg;
 	tmp_mcs_tp = minstrel_ht_get_tp_avg(mi, tmp_group, tmp_idx, tmp_prob);
 
@@ -600,14 +600,14 @@ minstrel_ht_prob_rate_reduce_streams(struct minstrel_ht_sta *mi)
 	if (!mi->sta->ht_cap.ht_supported)
 		return;
 
-	tmp_max_streams = minstrel_mcs_groups[mi->max_tp_rate[0] /
-			  MCS_GROUP_RATES].streams;
+	group = MI_RATE_GROUP(mi->max_tp_rate[0]);
+	tmp_max_streams = minstrel_mcs_groups[group].streams;
 	for (group = 0; group < ARRAY_SIZE(minstrel_mcs_groups); group++) {
 		mg = &mi->groups[group];
 		if (!mi->supported[group] || group == MINSTREL_CCK_GROUP)
 			continue;
 
-		tmp_idx = mg->max_group_prob_rate % MCS_GROUP_RATES;
+		tmp_idx = MI_RATE_IDX(mg->max_group_prob_rate);
 		tmp_prob = mi->groups[group].rates[tmp_idx].prob_avg;
 
 		if (tmp_tp < minstrel_ht_get_tp_avg(mi, group, tmp_idx, tmp_prob) &&
@@ -644,8 +644,8 @@ minstrel_ht_find_probe_rates(struct minstrel_ht_sta *mi, u16 *rates, int *n_rate
 	int i, g, max_dur;
 	int tp_idx;
 
-	tp_group = &minstrel_mcs_groups[mi->max_tp_rate[0] / MCS_GROUP_RATES];
-	tp_idx = mi->max_tp_rate[0] % MCS_GROUP_RATES;
+	tp_group = &minstrel_mcs_groups[MI_RATE_GROUP(mi->max_tp_rate[0])];
+	tp_idx = MI_RATE_IDX(mi->max_tp_rate[0]);
 
 	max_dur = minstrel_get_duration(mi->max_tp_rate[0]);
 	if (faster_rate)
@@ -670,7 +670,7 @@ minstrel_ht_find_probe_rates(struct minstrel_ht_sta *mi, u16 *rates, int *n_rate
 			if ((group->duration[i] << group->shift) > max_dur)
 				continue;
 
-			idx = g * MCS_GROUP_RATES + i;
+			idx = MI_RATE(g, i);
 			if (idx == mi->max_tp_rate[0])
 				continue;
 
@@ -712,10 +712,10 @@ minstrel_ht_rate_sample_switch(struct minstrel_priv *mp,
 
 	/* If no suitable rate was found, try to pick the next one in the group */
 	if (!n_rates) {
-		int g_idx = mi->max_tp_rate[0] / MCS_GROUP_RATES;
+		int g_idx = MI_RATE_GROUP(mi->max_tp_rate[0]);
 		u16 supported = mi->supported[g_idx];
 
-		supported >>= mi->max_tp_rate[0] % MCS_GROUP_RATES;
+		supported >>= MI_RATE_IDX(mi->max_tp_rate[0]);
 		for (i = 0; supported; supported >>= 1, i++) {
 			if (!(supported & 1))
 				continue;
@@ -856,22 +856,26 @@ minstrel_ht_update_stats(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
 
 	memset(tmp_mcs_tp_rate, 0, sizeof(tmp_mcs_tp_rate));
 	memset(tmp_legacy_tp_rate, 0, sizeof(tmp_legacy_tp_rate));
+
 	if (mi->supported[MINSTREL_CCK_GROUP])
-		for (j = 0; j < ARRAY_SIZE(tmp_legacy_tp_rate); j++)
-			tmp_legacy_tp_rate[j] = MINSTREL_CCK_GROUP * MCS_GROUP_RATES;
+		group = MINSTREL_CCK_GROUP;
 	else if (mi->supported[MINSTREL_OFDM_GROUP])
-		for (j = 0; j < ARRAY_SIZE(tmp_legacy_tp_rate); j++)
-			tmp_legacy_tp_rate[j] = MINSTREL_OFDM_GROUP * MCS_GROUP_RATES;
+		group = MINSTREL_OFDM_GROUP;
+
+	index = MI_RATE(group, 0);
+	for (j = 0; j < ARRAY_SIZE(tmp_legacy_tp_rate); j++)
+		tmp_legacy_tp_rate[j] = index;
 
 	if (mi->supported[MINSTREL_VHT_GROUP_0])
-		index = MINSTREL_VHT_GROUP_0 * MCS_GROUP_RATES;
+		group = MINSTREL_VHT_GROUP_0;
 	else if (ht_supported)
-		index = MINSTREL_HT_GROUP_0 * MCS_GROUP_RATES;
+		group = MINSTREL_HT_GROUP_0;
 	else if (mi->supported[MINSTREL_CCK_GROUP])
-		index = MINSTREL_CCK_GROUP * MCS_GROUP_RATES;
+		group = MINSTREL_CCK_GROUP;
 	else
-		index = MINSTREL_OFDM_GROUP * MCS_GROUP_RATES;
+		group = MINSTREL_OFDM_GROUP;
 
+	index = MI_RATE(group, 0);
 	tmp_max_prob_rate = index;
 	for (j = 0; j < ARRAY_SIZE(tmp_mcs_tp_rate); j++)
 		tmp_mcs_tp_rate[j] = index;
@@ -888,7 +892,7 @@ minstrel_ht_update_stats(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
 
 		/* (re)Initialize group rate indexes */
 		for(j = 0; j < MAX_THR_RATES; j++)
-			tmp_group_tp_rate[j] = MCS_GROUP_RATES * group;
+			tmp_group_tp_rate[j] = MI_RATE(group, 0);
 
 		if (group == MINSTREL_CCK_GROUP && ht_supported)
 			tp_rate = tmp_legacy_tp_rate;
@@ -897,7 +901,7 @@ minstrel_ht_update_stats(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
 			if (!(mi->supported[group] & BIT(i)))
 				continue;
 
-			index = MCS_GROUP_RATES * group + i;
+			index = MI_RATE(group, i);
 
 			mrs = &mg->rates[i];
 			mrs->retry_updated = false;
@@ -929,13 +933,13 @@ minstrel_ht_update_stats(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
 			continue;
 
 		mg = &mi->groups[group];
-		mg->max_group_prob_rate = MCS_GROUP_RATES * group;
+		mg->max_group_prob_rate = MI_RATE(group, 0);
 
 		for (i = 0; i < MCS_GROUP_RATES; i++) {
 			if (!(mi->supported[group] & BIT(i)))
 				continue;
 
-			index = MCS_GROUP_RATES * group + i;
+			index = MI_RATE(group, i);
 
 			/* Find max probability rate per group and global */
 			minstrel_ht_set_best_prob_rate(mi, &tmp_max_prob_rate,
@@ -1022,7 +1026,7 @@ minstrel_downgrade_rate(struct minstrel_ht_sta *mi, u16 *idx, bool primary)
 {
 	int group, orig_group;
 
-	orig_group = group = *idx / MCS_GROUP_RATES;
+	orig_group = group = MI_RATE_GROUP(*idx);
 	while (group > 0) {
 		group--;
 
@@ -1206,7 +1210,7 @@ minstrel_calc_retransmit(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
 	ctime += (t_slot * cw) >> 1;
 	cw = min((cw << 1) | 1, mp->cw_max);
 
-	if (minstrel_ht_is_legacy_group(index / MCS_GROUP_RATES)) {
+	if (minstrel_ht_is_legacy_group(MI_RATE_GROUP(index))) {
 		overhead = mi->overhead_legacy;
 		overhead_rtscts = mi->overhead_legacy_rtscts;
 	} else {
@@ -1239,7 +1243,7 @@ static void
 minstrel_ht_set_rate(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
                      struct ieee80211_sta_rates *ratetbl, int offset, int index)
 {
-	int group_idx = index / MCS_GROUP_RATES;
+	int group_idx = MI_RATE_GROUP(index);
 	const struct mcs_group *group = &minstrel_mcs_groups[group_idx];
 	struct minstrel_rate_stats *mrs;
 	u8 idx;
@@ -1259,7 +1263,7 @@ minstrel_ht_set_rate(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
 		ratetbl->rate[offset].count_rts = mrs->retry_count_rtscts;
 	}
 
-	index %= MCS_GROUP_RATES;
+	index = MI_RATE_IDX(index);
 	if (group_idx == MINSTREL_CCK_GROUP)
 		idx = mp->cck_rates[index % ARRAY_SIZE(mp->cck_rates)];
 	else if (group_idx == MINSTREL_OFDM_GROUP)
@@ -1289,17 +1293,17 @@ minstrel_ht_set_rate(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
 static inline int
 minstrel_ht_get_prob_avg(struct minstrel_ht_sta *mi, int rate)
 {
-	int group = rate / MCS_GROUP_RATES;
-	rate %= MCS_GROUP_RATES;
+	int group = MI_RATE_GROUP(rate);
+	rate = MI_RATE_IDX(rate);
 	return mi->groups[group].rates[rate].prob_avg;
 }
 
 static int
 minstrel_ht_get_max_amsdu_len(struct minstrel_ht_sta *mi)
 {
-	int group = mi->max_prob_rate / MCS_GROUP_RATES;
+	int group = MI_RATE_GROUP(mi->max_prob_rate);
 	const struct mcs_group *g = &minstrel_mcs_groups[group];
-	int rate = mi->max_prob_rate % MCS_GROUP_RATES;
+	int rate = MI_RATE_IDX(mi->max_prob_rate);
 	unsigned int duration;
 
 	/* Disable A-MSDU if max_prob_rate is bad */
@@ -1405,7 +1409,7 @@ minstrel_get_sample_rate(struct minstrel_priv *mp, struct minstrel_ht_sta *mi)
 		return -1;
 
 	mrs = &mg->rates[sample_idx];
-	sample_idx += sample_group * MCS_GROUP_RATES;
+	sample_idx += MI_RATE(sample_group, 0);
 
 	tp_rate1 = mi->max_tp_rate[0];
 
@@ -1455,8 +1459,7 @@ minstrel_get_sample_rate(struct minstrel_priv *mp, struct minstrel_ht_sta *mi)
 	 * if the link is working perfectly.
 	 */
 
-	cur_max_tp_streams = minstrel_mcs_groups[tp_rate1 /
-		MCS_GROUP_RATES].streams;
+	cur_max_tp_streams = minstrel_mcs_groups[MI_RATE_GROUP(tp_rate1)].streams;
 	if (sample_dur >= minstrel_get_duration(tp_rate2) &&
 	    (cur_max_tp_streams - 1 <
 	     minstrel_mcs_groups[sample_group].streams ||
@@ -1484,7 +1487,7 @@ minstrel_ht_get_rate(void *priv, struct ieee80211_sta *sta, void *priv_sta,
 	int sample_idx;
 
 	if (!(info->flags & IEEE80211_TX_CTL_AMPDU) &&
-	    !minstrel_ht_is_legacy_group(mi->max_prob_rate / MCS_GROUP_RATES))
+	    !minstrel_ht_is_legacy_group(MI_RATE_GROUP(mi->max_prob_rate)))
 		minstrel_aggr_check(sta, txrc->skb);
 
 	info->flags |= mi->tx_flags;
@@ -1512,8 +1515,8 @@ minstrel_ht_get_rate(void *priv, struct ieee80211_sta *sta, void *priv_sta,
 	if (sample_idx < 0)
 		return;
 
-	sample_group = &minstrel_mcs_groups[sample_idx / MCS_GROUP_RATES];
-	sample_idx %= MCS_GROUP_RATES;
+	sample_group = &minstrel_mcs_groups[MI_RATE_GROUP(sample_idx)];
+	sample_idx = MI_RATE_IDX(sample_idx);
 
 	if (sample_group == &minstrel_mcs_groups[MINSTREL_CCK_GROUP] &&
 	    (sample_idx >= 4) != txrc->short_preamble)
@@ -1529,7 +1532,7 @@ minstrel_ht_get_rate(void *priv, struct ieee80211_sta *sta, void *priv_sta,
 		int idx = sample_idx % ARRAY_SIZE(mp->ofdm_rates[0]);
 		rate->idx = mp->ofdm_rates[mi->band][idx];
 	} else if (sample_group->flags & IEEE80211_TX_RC_VHT_MCS) {
-		ieee80211_rate_set_vht(rate, sample_idx % MCS_GROUP_RATES,
+		ieee80211_rate_set_vht(rate, MI_RATE_IDX(sample_idx),
 				       sample_group->streams);
 	} else {
 		rate->idx = sample_idx + (sample_group->streams - 1) * 8;
@@ -1898,8 +1901,8 @@ static u32 minstrel_ht_get_expected_throughput(void *priv_sta)
 	struct minstrel_ht_sta *mi = priv_sta;
 	int i, j, prob, tp_avg;
 
-	i = mi->max_tp_rate[0] / MCS_GROUP_RATES;
-	j = mi->max_tp_rate[0] % MCS_GROUP_RATES;
+	i = MI_RATE_GROUP(mi->max_tp_rate[0]);
+	j = MI_RATE_IDX(mi->max_tp_rate[0]);
 	prob = mi->groups[i].rates[j].prob_avg;
 
 	/* convert tp_avg from pkt per second in kbps */
diff --git a/net/mac80211/rc80211_minstrel_ht.h b/net/mac80211/rc80211_minstrel_ht.h
index 7d6d0b720f6d..5912f7dc5267 100644
--- a/net/mac80211/rc80211_minstrel_ht.h
+++ b/net/mac80211/rc80211_minstrel_ht.h
@@ -6,6 +6,8 @@
 #ifndef __RC_MINSTREL_HT_H
 #define __RC_MINSTREL_HT_H
 
+#include <linux/bitfield.h>
+
 /* number of highest throughput rates to consider*/
 #define MAX_THR_RATES 4
 #define SAMPLE_COLUMNS	10	/* number of columns in sample table */
@@ -57,6 +59,17 @@
 
 #define MCS_GROUP_RATES		10
 
+#define MI_RATE_IDX_MASK	GENMASK(3, 0)
+#define MI_RATE_GROUP_MASK	GENMASK(15, 4)
+
+#define MI_RATE(_group, _idx)				\
+	(FIELD_PREP(MI_RATE_GROUP_MASK, _group) |	\
+	 FIELD_PREP(MI_RATE_IDX_MASK, _idx))
+
+#define MI_RATE_IDX(_rate) FIELD_GET(MI_RATE_IDX_MASK, _rate)
+#define MI_RATE_GROUP(_rate) FIELD_GET(MI_RATE_GROUP_MASK, _rate)
+
+
 struct minstrel_priv {
 	struct ieee80211_hw *hw;
 	bool has_mrr;
diff --git a/net/mac80211/rc80211_minstrel_ht_debugfs.c b/net/mac80211/rc80211_minstrel_ht_debugfs.c
index 3b7af242cde6..067d10383fa7 100644
--- a/net/mac80211/rc80211_minstrel_ht_debugfs.c
+++ b/net/mac80211/rc80211_minstrel_ht_debugfs.c
@@ -56,7 +56,7 @@ minstrel_ht_stats_dump(struct minstrel_ht_sta *mi, int i, char *p)
 
 	for (j = 0; j < MCS_GROUP_RATES; j++) {
 		struct minstrel_rate_stats *mrs = &mi->groups[i].rates[j];
-		int idx = i * MCS_GROUP_RATES + j;
+		int idx = MI_RATE(i, j);
 		unsigned int duration;
 
 		if (!(mi->supported[i] & BIT(j)))
@@ -201,7 +201,7 @@ minstrel_ht_stats_csv_dump(struct minstrel_ht_sta *mi, int i, char *p)
 
 	for (j = 0; j < MCS_GROUP_RATES; j++) {
 		struct minstrel_rate_stats *mrs = &mi->groups[i].rates[j];
-		int idx = i * MCS_GROUP_RATES + j;
+		int idx = MI_RATE(i, j);
 		unsigned int duration;
 
 		if (!(mi->supported[i] & BIT(j)))
-- 
2.28.0

[PATCH 2/6] mac80211: minstrel_ht: update total packets counter in tx status path

[Felix Fietkau]

Keep the update in one place and prepare for further rework

Signed-off-by: Felix Fietkau <nbd@nbd.name>
---
 net/mac80211/rc80211_minstrel_ht.c | 21 ++++++++++-----------
 1 file changed, 10 insertions(+), 11 deletions(-)

diff --git a/net/mac80211/rc80211_minstrel_ht.c b/net/mac80211/rc80211_minstrel_ht.c
index a3b86fd300f0..2ef748ca5355 100644
--- a/net/mac80211/rc80211_minstrel_ht.c
+++ b/net/mac80211/rc80211_minstrel_ht.c
@@ -1093,6 +1093,16 @@ minstrel_ht_tx_status(void *priv, struct ieee80211_supported_band *sband,
 		info->status.ampdu_len = 1;
 	}
 
+	/* wraparound */
+	if (mi->total_packets >= ~0 - info->status.ampdu_len) {
+		mi->total_packets = 0;
+		mi->sample_packets = 0;
+	}
+
+	mi->total_packets += info->status.ampdu_len;
+	if (info->flags & IEEE80211_TX_CTL_RATE_CTRL_PROBE)
+		mi->sample_packets += info->status.ampdu_len;
+
 	mi->ampdu_packets++;
 	mi->ampdu_len += info->status.ampdu_len;
 
@@ -1104,9 +1114,6 @@ minstrel_ht_tx_status(void *priv, struct ieee80211_supported_band *sband,
 		mi->sample_count--;
 	}
 
-	if (info->flags & IEEE80211_TX_CTL_RATE_CTRL_PROBE)
-		mi->sample_packets += info->status.ampdu_len;
-
 	if (mi->sample_mode != MINSTREL_SAMPLE_IDLE)
 		rate_sample = minstrel_get_ratestats(mi, mi->sample_rate);
 
@@ -1504,14 +1511,6 @@ minstrel_ht_get_rate(void *priv, struct ieee80211_sta *sta, void *priv_sta,
 	else
 		sample_idx = minstrel_get_sample_rate(mp, mi);
 
-	mi->total_packets++;
-
-	/* wraparound */
-	if (mi->total_packets == ~0) {
-		mi->total_packets = 0;
-		mi->sample_packets = 0;
-	}
-
 	if (sample_idx < 0)
 		return;
 
-- 
2.28.0

[PATCH 3/6] mac80211: minstrel_ht: reduce the need to sample slower rates

[Felix Fietkau]

In order to more gracefully be able to fall back to lower rates without too
much throughput fluctuations, initialize all untested rates below tested ones
to the maximum probabilty of higher rates.
Usually this leads to untested lower rates getting initialized with a
probability value of 100%, making them better candidates for fallback without
having to rely on random probing

Signed-off-by: Felix Fietkau <nbd@nbd.name>
---
 net/mac80211/rc80211_minstrel_ht.c | 18 ++++++++----------
 net/mac80211/rc80211_minstrel_ht.h |  2 --
 2 files changed, 8 insertions(+), 12 deletions(-)

diff --git a/net/mac80211/rc80211_minstrel_ht.c b/net/mac80211/rc80211_minstrel_ht.c
index 2ef748ca5355..22adcebb8d51 100644
--- a/net/mac80211/rc80211_minstrel_ht.c
+++ b/net/mac80211/rc80211_minstrel_ht.c
@@ -791,14 +791,11 @@ minstrel_ht_calc_rate_stats(struct minstrel_priv *mp,
 	unsigned int cur_prob;
 
 	if (unlikely(mrs->attempts > 0)) {
-		mrs->sample_skipped = 0;
 		cur_prob = MINSTREL_FRAC(mrs->success, mrs->attempts);
 		minstrel_filter_avg_add(&mrs->prob_avg,
 					&mrs->prob_avg_1, cur_prob);
 		mrs->att_hist += mrs->attempts;
 		mrs->succ_hist += mrs->success;
-	} else {
-		mrs->sample_skipped++;
 	}
 
 	mrs->last_success = mrs->success;
@@ -851,7 +848,6 @@ minstrel_ht_update_stats(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
 		mi->ampdu_packets = 0;
 	}
 
-	mi->sample_slow = 0;
 	mi->sample_count = 0;
 
 	memset(tmp_mcs_tp_rate, 0, sizeof(tmp_mcs_tp_rate));
@@ -883,6 +879,7 @@ minstrel_ht_update_stats(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
 	/* Find best rate sets within all MCS groups*/
 	for (group = 0; group < ARRAY_SIZE(minstrel_mcs_groups); group++) {
 		u16 *tp_rate = tmp_mcs_tp_rate;
+		u16 last_prob = 0;
 
 		mg = &mi->groups[group];
 		if (!mi->supported[group])
@@ -897,7 +894,7 @@ minstrel_ht_update_stats(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
 		if (group == MINSTREL_CCK_GROUP && ht_supported)
 			tp_rate = tmp_legacy_tp_rate;
 
-		for (i = 0; i < MCS_GROUP_RATES; i++) {
+		for (i = MCS_GROUP_RATES - 1; i >= 0; i--) {
 			if (!(mi->supported[group] & BIT(i)))
 				continue;
 
@@ -906,6 +903,11 @@ minstrel_ht_update_stats(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
 			mrs = &mg->rates[i];
 			mrs->retry_updated = false;
 			minstrel_ht_calc_rate_stats(mp, mrs);
+
+			if (mrs->att_hist)
+				last_prob = max(last_prob, mrs->prob_avg);
+			else
+				mrs->prob_avg = max(last_prob, mrs->prob_avg);
 			cur_prob = mrs->prob_avg;
 
 			if (minstrel_ht_get_tp_avg(mi, group, i, cur_prob) == 0)
@@ -1470,13 +1472,9 @@ minstrel_get_sample_rate(struct minstrel_priv *mp, struct minstrel_ht_sta *mi)
 	if (sample_dur >= minstrel_get_duration(tp_rate2) &&
 	    (cur_max_tp_streams - 1 <
 	     minstrel_mcs_groups[sample_group].streams ||
-	     sample_dur >= minstrel_get_duration(mi->max_prob_rate))) {
-		if (mrs->sample_skipped < 20)
+	     sample_dur >= minstrel_get_duration(mi->max_prob_rate)))
 			return -1;
 
-		if (mi->sample_slow++ > 2)
-			return -1;
-	}
 	mi->sample_tries--;
 
 	return sample_idx;
diff --git a/net/mac80211/rc80211_minstrel_ht.h b/net/mac80211/rc80211_minstrel_ht.h
index 5912f7dc5267..ebb2b88f44d9 100644
--- a/net/mac80211/rc80211_minstrel_ht.h
+++ b/net/mac80211/rc80211_minstrel_ht.h
@@ -123,7 +123,6 @@ struct minstrel_rate_stats {
 	u8 retry_count;
 	u8 retry_count_rtscts;
 
-	u8 sample_skipped;
 	bool retry_updated;
 };
 
@@ -179,7 +178,6 @@ struct minstrel_ht_sta {
 	u8 sample_wait;
 	u8 sample_tries;
 	u8 sample_count;
-	u8 sample_slow;
 
 	enum minstrel_sample_mode sample_mode;
 	u16 sample_rate;
-- 
2.28.0

[PATCH 4/6] mac80211: minstrel_ht: significantly redesign the rate probing strategy

[Felix Fietkau]

The biggest flaw in current minstrel_ht is the fact that it needs way too
many probing packets to be able to quickly find the best rate.
Depending on the wifi hardware and operating mode, this can significantly
reduce throughput when not operating at the highest available data rate.

In order to be able to significantly reduce the amount of rate sampling,
we need a much smarter selection of probing rates.

The new approach introduced by this patch maintains a limited set of
available rates to be tested during a statistics window.

They are split into distinct categories:
- MINSTREL_SAMPLE_TYPE_INC - incremental rate upgrade:
  Pick the next rate group and find the first rate that is faster than
  the current max. throughput rate
- MINSTREL_SAMPLE_TYPE_JUMP - random testing of higher rates:
  Pick a random rate from the next group that is faster than the current
  max throughput rate. This allows faster adaptation when the link changes
  significantly
- MINSTREL_SAMPLE_TYPE_SLOW - test a rate between max_prob, max_tp2 and
  max_tp in order to reduce the gap between them

In order to prioritize sampling, every 6 attempts are split into 3x INC,
2x JUMP, 1x SLOW.

Available rates are checked and refilled on every stats window update.

With this approach, we finally get a very small delta in throughput when
comparing setting the optimal data rate as a fixed rate vs normal rate
control operation.

Signed-off-by: Felix Fietkau <nbd@nbd.name>
---
 net/mac80211/rc80211_minstrel_ht.c | 550 +++++++++++++++++------------
 net/mac80211/rc80211_minstrel_ht.h |  25 +-
 2 files changed, 336 insertions(+), 239 deletions(-)

diff --git a/net/mac80211/rc80211_minstrel_ht.c b/net/mac80211/rc80211_minstrel_ht.c
index 22adcebb8d51..95e10c4b1539 100644
--- a/net/mac80211/rc80211_minstrel_ht.c
+++ b/net/mac80211/rc80211_minstrel_ht.c
@@ -266,6 +266,14 @@ const struct mcs_group minstrel_mcs_groups[] = {
 const s16 minstrel_cck_bitrates[4] = { 10, 20, 55, 110 };
 const s16 minstrel_ofdm_bitrates[8] = { 60, 90, 120, 180, 240, 360, 480, 540 };
 static u8 sample_table[SAMPLE_COLUMNS][MCS_GROUP_RATES] __read_mostly;
+static const u8 minstrel_sample_seq[] = {
+	MINSTREL_SAMPLE_TYPE_INC,
+	MINSTREL_SAMPLE_TYPE_JUMP,
+	MINSTREL_SAMPLE_TYPE_INC,
+	MINSTREL_SAMPLE_TYPE_JUMP,
+	MINSTREL_SAMPLE_TYPE_INC,
+	MINSTREL_SAMPLE_TYPE_SLOW,
+};
 
 static void
 minstrel_ht_update_rates(struct minstrel_priv *mp, struct minstrel_ht_sta *mi);
@@ -620,77 +628,31 @@ minstrel_ht_prob_rate_reduce_streams(struct minstrel_ht_sta *mi)
 	}
 }
 
-static bool
-minstrel_ht_probe_group(struct minstrel_ht_sta *mi, const struct mcs_group *tp_group,
-						int tp_idx, const struct mcs_group *group)
-{
-	if (group->bw < tp_group->bw)
-		return false;
-
-	if (group->streams == tp_group->streams)
-		return true;
-
-	if (tp_idx < 4 && group->streams == tp_group->streams - 1)
-		return true;
-
-	return group->streams == tp_group->streams + 1;
-}
-
-static void
-minstrel_ht_find_probe_rates(struct minstrel_ht_sta *mi, u16 *rates, int *n_rates,
-			     bool faster_rate)
+static u16
+__minstrel_ht_get_sample_rate(struct minstrel_ht_sta *mi,
+			      enum minstrel_sample_type type)
 {
-	const struct mcs_group *group, *tp_group;
-	int i, g, max_dur;
-	int tp_idx;
-
-	tp_group = &minstrel_mcs_groups[MI_RATE_GROUP(mi->max_tp_rate[0])];
-	tp_idx = MI_RATE_IDX(mi->max_tp_rate[0]);
-
-	max_dur = minstrel_get_duration(mi->max_tp_rate[0]);
-	if (faster_rate)
-		max_dur -= max_dur / 16;
-
-	for (g = 0; g < MINSTREL_GROUPS_NB; g++) {
-		u16 supported = mi->supported[g];
-
-		if (!supported)
-			continue;
+	u16 *rates = mi->sample[type].sample_rates;
+	u16 cur;
+	int i;
 
-		group = &minstrel_mcs_groups[g];
-		if (!minstrel_ht_probe_group(mi, tp_group, tp_idx, group))
+	for (i = 0; i < MINSTREL_SAMPLE_RATES; i++) {
+		if (!rates[i])
 			continue;
 
-		for (i = 0; supported; supported >>= 1, i++) {
-			int idx;
-
-			if (!(supported & 1))
-				continue;
-
-			if ((group->duration[i] << group->shift) > max_dur)
-				continue;
-
-			idx = MI_RATE(g, i);
-			if (idx == mi->max_tp_rate[0])
-				continue;
-
-			rates[(*n_rates)++] = idx;
-			break;
-		}
+		cur = rates[i];
+		rates[i] = 0;
+		return cur;
 	}
+
+	return 0;
 }
 
 static void
 minstrel_ht_rate_sample_switch(struct minstrel_priv *mp,
 			       struct minstrel_ht_sta *mi)
 {
-	struct minstrel_rate_stats *mrs;
-	u16 rates[MINSTREL_GROUPS_NB];
-	int n_rates = 0;
-	int probe_rate = 0;
-	bool faster_rate;
-	int i;
-	u8 random;
+	u16 rate;
 
 	/*
 	 * Use rate switching instead of probing packets for devices with
@@ -699,43 +661,11 @@ minstrel_ht_rate_sample_switch(struct minstrel_priv *mp,
 	if (mp->hw->max_rates > 1)
 		return;
 
-	/*
-	 * If the current EWMA prob is >75%, look for a rate that's 6.25%
-	 * faster than the max tp rate.
-	 * If that fails, look again for a rate that is at least as fast
-	 */
-	mrs = minstrel_get_ratestats(mi, mi->max_tp_rate[0]);
-	faster_rate = mrs->prob_avg > MINSTREL_FRAC(75, 100);
-	minstrel_ht_find_probe_rates(mi, rates, &n_rates, faster_rate);
-	if (!n_rates && faster_rate)
-		minstrel_ht_find_probe_rates(mi, rates, &n_rates, false);
-
-	/* If no suitable rate was found, try to pick the next one in the group */
-	if (!n_rates) {
-		int g_idx = MI_RATE_GROUP(mi->max_tp_rate[0]);
-		u16 supported = mi->supported[g_idx];
-
-		supported >>= MI_RATE_IDX(mi->max_tp_rate[0]);
-		for (i = 0; supported; supported >>= 1, i++) {
-			if (!(supported & 1))
-				continue;
-
-			probe_rate = mi->max_tp_rate[0] + i;
-			goto out;
-		}
-
+	rate = __minstrel_ht_get_sample_rate(mi, MINSTREL_SAMPLE_TYPE_INC);
+	if (!rate)
 		return;
-	}
 
-	i = 0;
-	if (n_rates > 1) {
-		random = prandom_u32();
-		i = random % n_rates;
-	}
-	probe_rate = rates[i];
-
-out:
-	mi->sample_rate = probe_rate;
+	mi->sample_rate = rate;
 	mi->sample_mode = MINSTREL_SAMPLE_ACTIVE;
 }
 
@@ -804,6 +734,274 @@ minstrel_ht_calc_rate_stats(struct minstrel_priv *mp,
 	mrs->attempts = 0;
 }
 
+static bool
+minstrel_ht_find_sample_rate(struct minstrel_ht_sta *mi, int type, int idx)
+{
+	int i;
+
+	for (i = 0; i < MINSTREL_SAMPLE_RATES; i++) {
+		u16 cur = mi->sample[type].sample_rates[i];
+
+		if (cur == idx)
+			return true;
+
+		if (!cur)
+			break;
+	}
+
+	return false;
+}
+
+static int
+minstrel_ht_move_sample_rates(struct minstrel_ht_sta *mi, int type,
+			      u32 fast_rate_dur, u32 slow_rate_dur)
+{
+	u16 *rates = mi->sample[type].sample_rates;
+	int i, j;
+
+	for (i = 0, j = 0; i < MINSTREL_SAMPLE_RATES; i++) {
+		u32 duration;
+		bool valid = false;
+		u16 cur;
+
+		cur = rates[i];
+		if (!cur)
+			continue;
+
+		duration = minstrel_get_duration(cur);
+		switch (type) {
+		case MINSTREL_SAMPLE_TYPE_SLOW:
+			valid = duration > fast_rate_dur &&
+				duration < slow_rate_dur;
+			break;
+		case MINSTREL_SAMPLE_TYPE_INC:
+		case MINSTREL_SAMPLE_TYPE_JUMP:
+			valid = duration < fast_rate_dur;
+			break;
+		default:
+			valid = false;
+			break;
+		}
+
+		if (!valid) {
+			rates[i] = 0;
+			continue;
+		}
+
+		if (i == j)
+			continue;
+
+		rates[j++] = cur;
+		rates[i] = 0;
+	}
+
+	return j;
+}
+
+static int
+minstrel_ht_group_min_rate_offset(struct minstrel_ht_sta *mi, int group,
+				  u32 max_duration)
+{
+	u16 supported = mi->supported[group];
+	int i;
+
+	for (i = 0; i < MCS_GROUP_RATES && supported; i++, supported >>= 1) {
+		if (!(supported & BIT(0)))
+			continue;
+
+		if (minstrel_get_duration(MI_RATE(group, i)) >= max_duration)
+			continue;
+
+		return i;
+	}
+
+	return -1;
+}
+
+/*
+ * Incremental update rates:
+ * Flip through groups and pick the first group rate that is faster than the
+ * highest currently selected rate
+ */
+static u16
+minstrel_ht_next_inc_rate(struct minstrel_ht_sta *mi, u32 fast_rate_dur)
+{
+	struct minstrel_mcs_group_data *mg;
+	u8 type = MINSTREL_SAMPLE_TYPE_INC;
+	int i, index = 0;
+	u8 group;
+
+	group = mi->sample[type].sample_group;
+	for (i = 0; i < ARRAY_SIZE(minstrel_mcs_groups); i++) {
+		group = (group + 1) % ARRAY_SIZE(minstrel_mcs_groups);
+		mg = &mi->groups[group];
+
+		index = minstrel_ht_group_min_rate_offset(mi, group,
+							  fast_rate_dur);
+		if (index < 0)
+			continue;
+
+		index = MI_RATE(group, index & 0xf);
+		if (!minstrel_ht_find_sample_rate(mi, type, index))
+			goto out;
+	}
+	index = 0;
+
+out:
+	mi->sample[type].sample_group = group;
+
+	return index;
+}
+
+static int
+minstrel_ht_next_group_sample_rate(struct minstrel_ht_sta *mi, int group,
+				   u16 supported, int offset)
+{
+	struct minstrel_mcs_group_data *mg = &mi->groups[group];
+	u16 idx;
+	int i;
+
+	for (i = 0; i < MCS_GROUP_RATES; i++) {
+		idx = sample_table[mg->column][mg->index];
+		if (++mg->index >= MCS_GROUP_RATES) {
+			mg->index = 0;
+			if (++mg->column >= ARRAY_SIZE(sample_table))
+				mg->column = 0;
+		}
+
+		if (idx < offset)
+			continue;
+
+		if (!(supported & BIT(idx)))
+			continue;
+
+		return MI_RATE(group, idx);
+	}
+
+	return -1;
+}
+
+/*
+ * Jump rates:
+ * Sample random rates, use those that are faster than the highest
+ * currently selected rate. Rates between the fastest and the slowest
+ * get sorted into the slow sample bucket, but only if it has room
+ */
+static u16
+minstrel_ht_next_jump_rate(struct minstrel_ht_sta *mi, u32 fast_rate_dur,
+			   u32 slow_rate_dur, int *slow_rate_ofs)
+{
+	struct minstrel_mcs_group_data *mg;
+	struct minstrel_rate_stats *mrs;
+	u32 max_duration = slow_rate_dur;
+	int i, index, offset;
+	u16 *slow_rates;
+	u16 supported;
+	u32 duration;
+	u8 group;
+
+	if (*slow_rate_ofs >= MINSTREL_SAMPLE_RATES)
+		max_duration = fast_rate_dur;
+
+	slow_rates = mi->sample[MINSTREL_SAMPLE_TYPE_SLOW].sample_rates;
+	group = mi->sample[MINSTREL_SAMPLE_TYPE_JUMP].sample_group;
+	for (i = 0; i < ARRAY_SIZE(minstrel_mcs_groups); i++) {
+		u8 type;
+
+		group = (group + 1) % ARRAY_SIZE(minstrel_mcs_groups);
+		mg = &mi->groups[group];
+
+		supported = mi->supported[group];
+		if (!supported)
+			continue;
+
+		offset = minstrel_ht_group_min_rate_offset(mi, group,
+							   max_duration);
+		if (offset < 0)
+			continue;
+
+		index = minstrel_ht_next_group_sample_rate(mi, group, supported,
+							   offset);
+		if (index < 0)
+			continue;
+
+		duration = minstrel_get_duration(index);
+		if (duration < fast_rate_dur)
+			type = MINSTREL_SAMPLE_TYPE_JUMP;
+		else
+			type = MINSTREL_SAMPLE_TYPE_SLOW;
+
+		if (minstrel_ht_find_sample_rate(mi, type, index))
+			continue;
+
+		if (type == MINSTREL_SAMPLE_TYPE_JUMP)
+			goto found;
+
+		if (*slow_rate_ofs >= MINSTREL_SAMPLE_RATES)
+			continue;
+
+		if (duration >= slow_rate_dur)
+			continue;
+
+		/* skip slow rates with high success probability */
+		mrs = minstrel_get_ratestats(mi, index);
+		if (mrs->prob_avg > MINSTREL_FRAC(95, 100))
+			continue;
+
+		slow_rates[(*slow_rate_ofs)++] = index;
+		if (*slow_rate_ofs >= MINSTREL_SAMPLE_RATES)
+			max_duration = fast_rate_dur;
+	}
+	index = 0;
+
+found:
+	mi->sample[MINSTREL_SAMPLE_TYPE_JUMP].sample_group = group;
+
+	return index;
+}
+
+static void
+minstrel_ht_refill_sample_rates(struct minstrel_ht_sta *mi)
+{
+	u32 prob_dur = minstrel_get_duration(mi->max_prob_rate);
+	u32 tp_dur = minstrel_get_duration(mi->max_tp_rate[0]);
+	u32 tp2_dur = minstrel_get_duration(mi->max_tp_rate[1]);
+	u32 fast_rate_dur = min(min(tp_dur, tp2_dur), prob_dur);
+	u32 slow_rate_dur = max(max(tp_dur, tp2_dur), prob_dur);
+	u16 *rates;
+	int i, j;
+
+	rates = mi->sample[MINSTREL_SAMPLE_TYPE_INC].sample_rates;
+	i = minstrel_ht_move_sample_rates(mi, MINSTREL_SAMPLE_TYPE_INC,
+					  fast_rate_dur, slow_rate_dur);
+	while (i < MINSTREL_SAMPLE_RATES) {
+		rates[i] = minstrel_ht_next_inc_rate(mi, tp_dur);
+		if (!rates[i])
+			break;
+
+		i++;
+	}
+
+	rates = mi->sample[MINSTREL_SAMPLE_TYPE_JUMP].sample_rates;
+	i = minstrel_ht_move_sample_rates(mi, MINSTREL_SAMPLE_TYPE_JUMP,
+					  fast_rate_dur, slow_rate_dur);
+	j = minstrel_ht_move_sample_rates(mi, MINSTREL_SAMPLE_TYPE_SLOW,
+					  fast_rate_dur, slow_rate_dur);
+	while (i < MINSTREL_SAMPLE_RATES) {
+		rates[i] = minstrel_ht_next_jump_rate(mi, fast_rate_dur,
+						      slow_rate_dur, &j);
+		if (!rates[i])
+			break;
+
+		i++;
+	}
+
+	for (i = 0; i < ARRAY_SIZE(mi->sample); i++)
+		memcpy(mi->sample[i].cur_sample_rates, mi->sample[i].sample_rates,
+		       sizeof(mi->sample[i].cur_sample_rates));
+}
+
+
 /*
  * Update rate statistics and select new primary rates
  *
@@ -848,8 +1046,6 @@ minstrel_ht_update_stats(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
 		mi->ampdu_packets = 0;
 	}
 
-	mi->sample_count = 0;
-
 	memset(tmp_mcs_tp_rate, 0, sizeof(tmp_mcs_tp_rate));
 	memset(tmp_legacy_tp_rate, 0, sizeof(tmp_legacy_tp_rate));
 
@@ -885,8 +1081,6 @@ minstrel_ht_update_stats(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
 		if (!mi->supported[group])
 			continue;
 
-		mi->sample_count++;
-
 		/* (re)Initialize group rate indexes */
 		for(j = 0; j < MAX_THR_RATES; j++)
 			tmp_group_tp_rate[j] = MI_RATE(group, 0);
@@ -953,9 +1147,7 @@ minstrel_ht_update_stats(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
 
 	/* Try to increase robustness of max_prob_rate*/
 	minstrel_ht_prob_rate_reduce_streams(mi);
-
-	/* try to sample half of all available rates during each interval */
-	mi->sample_count *= 4;
+	minstrel_ht_refill_sample_rates(mi);
 
 	if (sample)
 		minstrel_ht_rate_sample_switch(mp, mi);
@@ -972,6 +1164,7 @@ minstrel_ht_update_stats(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
 
 	/* Reset update timer */
 	mi->last_stats_update = jiffies;
+	mi->sample_time = jiffies;
 }
 
 static bool
@@ -1001,28 +1194,6 @@ minstrel_ht_txstat_valid(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
 	return false;
 }
 
-static void
-minstrel_set_next_sample_idx(struct minstrel_ht_sta *mi)
-{
-	struct minstrel_mcs_group_data *mg;
-
-	for (;;) {
-		mi->sample_group++;
-		mi->sample_group %= ARRAY_SIZE(minstrel_mcs_groups);
-		mg = &mi->groups[mi->sample_group];
-
-		if (!mi->supported[mi->sample_group])
-			continue;
-
-		if (++mg->index >= MCS_GROUP_RATES) {
-			mg->index = 0;
-			if (++mg->column >= ARRAY_SIZE(sample_table))
-				mg->column = 0;
-		}
-		break;
-	}
-}
-
 static void
 minstrel_downgrade_rate(struct minstrel_ht_sta *mi, u16 *idx, bool primary)
 {
@@ -1108,14 +1279,6 @@ minstrel_ht_tx_status(void *priv, struct ieee80211_supported_band *sband,
 	mi->ampdu_packets++;
 	mi->ampdu_len += info->status.ampdu_len;
 
-	if (!mi->sample_wait && !mi->sample_tries && mi->sample_count > 0) {
-		int avg_ampdu_len = minstrel_ht_avg_ampdu_len(mi);
-
-		mi->sample_wait = 16 + 2 * avg_ampdu_len;
-		mi->sample_tries = 1;
-		mi->sample_count--;
-	}
-
 	if (mi->sample_mode != MINSTREL_SAMPLE_IDLE)
 		rate_sample = minstrel_get_ratestats(mi, mi->sample_rate);
 
@@ -1387,97 +1550,20 @@ minstrel_ht_update_rates(struct minstrel_priv *mp, struct minstrel_ht_sta *mi)
 	rate_control_set_rates(mp->hw, mi->sta, rates);
 }
 
-static int
-minstrel_get_sample_rate(struct minstrel_priv *mp, struct minstrel_ht_sta *mi)
+static u16
+minstrel_ht_get_sample_rate(struct minstrel_priv *mp, struct minstrel_ht_sta *mi)
 {
-	struct minstrel_rate_stats *mrs;
-	struct minstrel_mcs_group_data *mg;
-	unsigned int sample_dur, sample_group, cur_max_tp_streams;
-	int tp_rate1, tp_rate2;
-	int sample_idx = 0;
-
-	if (mp->hw->max_rates == 1 && mp->sample_switch &&
-	    (mi->total_packets_cur >= SAMPLE_SWITCH_THR ||
-	     mp->sample_switch == 1))
-		return -1;
+	u8 seq;
 
-	if (mi->sample_wait > 0) {
-		mi->sample_wait--;
-		return -1;
-	}
-
-	if (!mi->sample_tries)
-		return -1;
-
-	sample_group = mi->sample_group;
-	mg = &mi->groups[sample_group];
-	sample_idx = sample_table[mg->column][mg->index];
-	minstrel_set_next_sample_idx(mi);
-
-	if (!(mi->supported[sample_group] & BIT(sample_idx)))
-		return -1;
-
-	mrs = &mg->rates[sample_idx];
-	sample_idx += MI_RATE(sample_group, 0);
-
-	tp_rate1 = mi->max_tp_rate[0];
-
-	/* Set tp_rate2 to the second highest max_tp_rate */
-	if (minstrel_get_duration(mi->max_tp_rate[0]) >
-	    minstrel_get_duration(mi->max_tp_rate[1])) {
-		tp_rate2 = mi->max_tp_rate[0];
+	if (mp->hw->max_rates > 1) {
+		seq = mi->sample_seq;
+		mi->sample_seq = (seq + 1) % ARRAY_SIZE(minstrel_sample_seq);
+		seq = minstrel_sample_seq[seq];
 	} else {
-		tp_rate2 = mi->max_tp_rate[1];
+		seq = MINSTREL_SAMPLE_TYPE_INC;
 	}
 
-	/*
-	 * Sampling might add some overhead (RTS, no aggregation)
-	 * to the frame. Hence, don't use sampling for the highest currently
-	 * used highest throughput or probability rate.
-	 */
-	if (sample_idx == mi->max_tp_rate[0] || sample_idx == mi->max_prob_rate)
-		return -1;
-
-	/*
-	 * Do not sample if the probability is already higher than 95%,
-	 * or if the rate is 3 times slower than the current max probability
-	 * rate, to avoid wasting airtime.
-	 */
-	sample_dur = minstrel_get_duration(sample_idx);
-	if (mrs->prob_avg > MINSTREL_FRAC(95, 100) ||
-	    minstrel_get_duration(mi->max_prob_rate) * 3 < sample_dur)
-		return -1;
-
-
-	/*
-	 * For devices with no configurable multi-rate retry, skip sampling
-	 * below the per-group max throughput rate, and only use one sampling
-	 * attempt per rate
-	 */
-	if (mp->hw->max_rates == 1 &&
-	    (minstrel_get_duration(mg->max_group_tp_rate[0]) < sample_dur ||
-	     mrs->attempts))
-		return -1;
-
-	/* Skip already sampled slow rates */
-	if (sample_dur >= minstrel_get_duration(tp_rate1) && mrs->attempts)
-		return -1;
-
-	/*
-	 * Make sure that lower rates get sampled only occasionally,
-	 * if the link is working perfectly.
-	 */
-
-	cur_max_tp_streams = minstrel_mcs_groups[MI_RATE_GROUP(tp_rate1)].streams;
-	if (sample_dur >= minstrel_get_duration(tp_rate2) &&
-	    (cur_max_tp_streams - 1 <
-	     minstrel_mcs_groups[sample_group].streams ||
-	     sample_dur >= minstrel_get_duration(mi->max_prob_rate)))
-			return -1;
-
-	mi->sample_tries--;
-
-	return sample_idx;
+	return __minstrel_ht_get_sample_rate(mi, seq);
 }
 
 static void
@@ -1489,7 +1575,7 @@ minstrel_ht_get_rate(void *priv, struct ieee80211_sta *sta, void *priv_sta,
 	struct ieee80211_tx_rate *rate = &info->status.rates[0];
 	struct minstrel_ht_sta *mi = priv_sta;
 	struct minstrel_priv *mp = priv;
-	int sample_idx;
+	u16 sample_idx;
 
 	if (!(info->flags & IEEE80211_TX_CTL_AMPDU) &&
 	    !minstrel_ht_is_legacy_group(MI_RATE_GROUP(mi->max_prob_rate)))
@@ -1505,11 +1591,19 @@ minstrel_ht_get_rate(void *priv, struct ieee80211_sta *sta, void *priv_sta,
 	/* Don't use EAPOL frames for sampling on non-mrr hw */
 	if (mp->hw->max_rates == 1 &&
 	    (info->control.flags & IEEE80211_TX_CTRL_PORT_CTRL_PROTO))
-		sample_idx = -1;
-	else
-		sample_idx = minstrel_get_sample_rate(mp, mi);
+		return;
+
+	if (mp->hw->max_rates == 1 && mp->sample_switch &&
+	    (mi->total_packets_cur >= SAMPLE_SWITCH_THR ||
+	     mp->sample_switch == 1))
+		return;
+
+	if (time_is_before_jiffies(mi->sample_time))
+		return;
 
-	if (sample_idx < 0)
+	mi->sample_time = jiffies + MINSTREL_SAMPLE_INTERVAL;
+	sample_idx = minstrel_ht_get_sample_rate(mp, mi);
+	if (!sample_idx)
 		return;
 
 	sample_group = &minstrel_mcs_groups[MI_RATE_GROUP(sample_idx)];
@@ -1630,16 +1724,6 @@ minstrel_ht_update_caps(void *priv, struct ieee80211_supported_band *sband,
 
 	mi->avg_ampdu_len = MINSTREL_FRAC(1, 1);
 
-	/* When using MRR, sample more on the first attempt, without delay */
-	if (mp->has_mrr) {
-		mi->sample_count = 16;
-		mi->sample_wait = 0;
-	} else {
-		mi->sample_count = 8;
-		mi->sample_wait = 8;
-	}
-	mi->sample_tries = 4;
-
 	if (!use_vht) {
 		stbc = (ht_cap & IEEE80211_HT_CAP_RX_STBC) >>
 			IEEE80211_HT_CAP_RX_STBC_SHIFT;
diff --git a/net/mac80211/rc80211_minstrel_ht.h b/net/mac80211/rc80211_minstrel_ht.h
index ebb2b88f44d9..0d8c15f83f5d 100644
--- a/net/mac80211/rc80211_minstrel_ht.h
+++ b/net/mac80211/rc80211_minstrel_ht.h
@@ -69,6 +69,8 @@
 #define MI_RATE_IDX(_rate) FIELD_GET(MI_RATE_IDX_MASK, _rate)
 #define MI_RATE_GROUP(_rate) FIELD_GET(MI_RATE_GROUP_MASK, _rate)
 
+#define MINSTREL_SAMPLE_RATES		5 /* rates per sample type */
+#define MINSTREL_SAMPLE_INTERVAL	(HZ / 50)
 
 struct minstrel_priv {
 	struct ieee80211_hw *hw;
@@ -126,6 +128,13 @@ struct minstrel_rate_stats {
 	bool retry_updated;
 };
 
+enum minstrel_sample_type {
+	MINSTREL_SAMPLE_TYPE_INC,
+	MINSTREL_SAMPLE_TYPE_JUMP,
+	MINSTREL_SAMPLE_TYPE_SLOW,
+	__MINSTREL_SAMPLE_TYPE_MAX
+};
+
 struct minstrel_mcs_group_data {
 	u8 index;
 	u8 column;
@@ -144,6 +153,12 @@ enum minstrel_sample_mode {
 	MINSTREL_SAMPLE_PENDING,
 };
 
+struct minstrel_sample_category {
+	u8 sample_group;
+	u16 sample_rates[MINSTREL_SAMPLE_RATES];
+	u16 cur_sample_rates[MINSTREL_SAMPLE_RATES];
+};
+
 struct minstrel_ht_sta {
 	struct ieee80211_sta *sta;
 
@@ -175,16 +190,14 @@ struct minstrel_ht_sta {
 	/* tx flags to add for frames for this sta */
 	u32 tx_flags;
 
-	u8 sample_wait;
-	u8 sample_tries;
-	u8 sample_count;
+	unsigned long sample_time;
+	struct minstrel_sample_category sample[__MINSTREL_SAMPLE_TYPE_MAX];
+
+	u8 sample_seq;
 
 	enum minstrel_sample_mode sample_mode;
 	u16 sample_rate;
 
-	/* current MCS group to be sampled */
-	u8 sample_group;
-
 	u8 band;
 
 	/* Bitfield of supported MCS rates of all groups */
-- 
2.28.0

Re: [PATCH 4/6] mac80211: minstrel_ht: significantly redesign the rate probing strategy

[Toke Høiland-Jørgensen]

Felix Fietkau <nbd@nbd.name> writes:

> The biggest flaw in current minstrel_ht is the fact that it needs way too
> many probing packets to be able to quickly find the best rate.
> Depending on the wifi hardware and operating mode, this can significantly
> reduce throughput when not operating at the highest available data rate.
>
> In order to be able to significantly reduce the amount of rate sampling,
> we need a much smarter selection of probing rates.
>
> The new approach introduced by this patch maintains a limited set of
> available rates to be tested during a statistics window.
>
> They are split into distinct categories:
> - MINSTREL_SAMPLE_TYPE_INC - incremental rate upgrade:
>   Pick the next rate group and find the first rate that is faster than
>   the current max. throughput rate
> - MINSTREL_SAMPLE_TYPE_JUMP - random testing of higher rates:
>   Pick a random rate from the next group that is faster than the current
>   max throughput rate. This allows faster adaptation when the link changes
>   significantly
> - MINSTREL_SAMPLE_TYPE_SLOW - test a rate between max_prob, max_tp2 and
>   max_tp in order to reduce the gap between them
>
> In order to prioritize sampling, every 6 attempts are split into 3x INC,
> 2x JUMP, 1x SLOW.
>
> Available rates are checked and refilled on every stats window update.

Very cool!

> With this approach, we finally get a very small delta in throughput when
> comparing setting the optimal data rate as a fixed rate vs normal rate
> control operation.

Can you quantify this "very small delta"? Would love to see some
benchmark data :)

-Toke

Re: [PATCH 4/6] mac80211: minstrel_ht: significantly redesign the rate probing strategy

[Felix Fietkau]

On 2021-01-25 12:56, Toke Høiland-Jørgensen wrote:
> Felix Fietkau <nbd@nbd.name> writes:
> 
>> The biggest flaw in current minstrel_ht is the fact that it needs way too
>> many probing packets to be able to quickly find the best rate.
>> Depending on the wifi hardware and operating mode, this can significantly
>> reduce throughput when not operating at the highest available data rate.
>>
>> In order to be able to significantly reduce the amount of rate sampling,
>> we need a much smarter selection of probing rates.
>>
>> The new approach introduced by this patch maintains a limited set of
>> available rates to be tested during a statistics window.
>>
>> They are split into distinct categories:
>> - MINSTREL_SAMPLE_TYPE_INC - incremental rate upgrade:
>>   Pick the next rate group and find the first rate that is faster than
>>   the current max. throughput rate
>> - MINSTREL_SAMPLE_TYPE_JUMP - random testing of higher rates:
>>   Pick a random rate from the next group that is faster than the current
>>   max throughput rate. This allows faster adaptation when the link changes
>>   significantly
>> - MINSTREL_SAMPLE_TYPE_SLOW - test a rate between max_prob, max_tp2 and
>>   max_tp in order to reduce the gap between them
>>
>> In order to prioritize sampling, every 6 attempts are split into 3x INC,
>> 2x JUMP, 1x SLOW.
>>
>> Available rates are checked and refilled on every stats window update.
> 
> Very cool!
> 
>> With this approach, we finally get a very small delta in throughput when
>> comparing setting the optimal data rate as a fixed rate vs normal rate
>> control operation.
> 
> Can you quantify this "very small delta"? Would love to see some
> benchmark data :)
Based on a quick test it seems to be around 5% (sometimes less) at VHT80
MCS6 nss=4 with ~350 mbit/s TCP throughput. I guess I might be able to
bring that down even further, once I optimize it some more.

- Felix

Re: [PATCH 4/6] mac80211: minstrel_ht: significantly redesign the rate probing strategy

[Toke Høiland-Jørgensen]

Felix Fietkau <nbd@nbd.name> writes:

> On 2021-01-25 12:56, Toke Høiland-Jørgensen wrote:
>> Felix Fietkau <nbd@nbd.name> writes:
>> 
>>> The biggest flaw in current minstrel_ht is the fact that it needs way too
>>> many probing packets to be able to quickly find the best rate.
>>> Depending on the wifi hardware and operating mode, this can significantly
>>> reduce throughput when not operating at the highest available data rate.
>>>
>>> In order to be able to significantly reduce the amount of rate sampling,
>>> we need a much smarter selection of probing rates.
>>>
>>> The new approach introduced by this patch maintains a limited set of
>>> available rates to be tested during a statistics window.
>>>
>>> They are split into distinct categories:
>>> - MINSTREL_SAMPLE_TYPE_INC - incremental rate upgrade:
>>>   Pick the next rate group and find the first rate that is faster than
>>>   the current max. throughput rate
>>> - MINSTREL_SAMPLE_TYPE_JUMP - random testing of higher rates:
>>>   Pick a random rate from the next group that is faster than the current
>>>   max throughput rate. This allows faster adaptation when the link changes
>>>   significantly
>>> - MINSTREL_SAMPLE_TYPE_SLOW - test a rate between max_prob, max_tp2 and
>>>   max_tp in order to reduce the gap between them
>>>
>>> In order to prioritize sampling, every 6 attempts are split into 3x INC,
>>> 2x JUMP, 1x SLOW.
>>>
>>> Available rates are checked and refilled on every stats window update.
>> 
>> Very cool!
>> 
>>> With this approach, we finally get a very small delta in throughput when
>>> comparing setting the optimal data rate as a fixed rate vs normal rate
>>> control operation.
>> 
>> Can you quantify this "very small delta"? Would love to see some
>> benchmark data :)
> Based on a quick test it seems to be around 5% (sometimes less) at VHT80
> MCS6 nss=4 with ~350 mbit/s TCP throughput. I guess I might be able to
> bring that down even further, once I optimize it some more.

Cool! And pre-patch?

-Toke

Re: [PATCH 4/6] mac80211: minstrel_ht: significantly redesign the rate probing strategy

[Felix Fietkau]

On 2021-01-25 22:21, Toke Høiland-Jørgensen wrote:
> Felix Fietkau <nbd@nbd.name> writes:
> 
>> On 2021-01-25 12:56, Toke Høiland-Jørgensen wrote:
>>> Felix Fietkau <nbd@nbd.name> writes:
>>>> With this approach, we finally get a very small delta in throughput when
>>>> comparing setting the optimal data rate as a fixed rate vs normal rate
>>>> control operation.
>>> 
>>> Can you quantify this "very small delta"? Would love to see some
>>> benchmark data :)
>> Based on a quick test it seems to be around 5% (sometimes less) at VHT80
>> MCS6 nss=4 with ~350 mbit/s TCP throughput. I guess I might be able to
>> bring that down even further, once I optimize it some more.
> 
> Cool! And pre-patch?
Some users reported more than 30%

- Felix

[PATCH 5/6] mac80211: minstrel_ht: show sampling rates in debugfs

[Felix Fietkau]

This makes it easier to see what rates are going to be tested next

Signed-off-by: Felix Fietkau <nbd@nbd.name>
---
 net/mac80211/rc80211_minstrel_ht_debugfs.c | 19 +++++++++++++++++--
 1 file changed, 17 insertions(+), 2 deletions(-)

diff --git a/net/mac80211/rc80211_minstrel_ht_debugfs.c b/net/mac80211/rc80211_minstrel_ht_debugfs.c
index 067d10383fa7..07aa877652a4 100644
--- a/net/mac80211/rc80211_minstrel_ht_debugfs.c
+++ b/net/mac80211/rc80211_minstrel_ht_debugfs.c
@@ -32,6 +32,18 @@ minstrel_stats_release(struct inode *inode, struct file *file)
 	return 0;
 }
 
+static bool
+minstrel_ht_is_sample_rate(struct minstrel_ht_sta *mi, int idx)
+{
+	int type, i;
+
+	for (type = 0; type < ARRAY_SIZE(mi->sample); type++)
+		for (i = 0; i < MINSTREL_SAMPLE_RATES; i++)
+			if (mi->sample[type].cur_sample_rates[i] == idx)
+				return true;
+	return false;
+}
+
 static char *
 minstrel_ht_stats_dump(struct minstrel_ht_sta *mi, int i, char *p)
 {
@@ -84,6 +96,7 @@ minstrel_ht_stats_dump(struct minstrel_ht_sta *mi, int i, char *p)
 		*(p++) = (idx == mi->max_tp_rate[2]) ? 'C' : ' ';
 		*(p++) = (idx == mi->max_tp_rate[3]) ? 'D' : ' ';
 		*(p++) = (idx == mi->max_prob_rate) ? 'P' : ' ';
+		*(p++) = minstrel_ht_is_sample_rate(mi, idx) ? 'S' : ' ';
 
 		if (gflags & IEEE80211_TX_RC_MCS) {
 			p += sprintf(p, "  MCS%-2u", (mg->streams - 1) * 8 + j);
@@ -145,9 +158,9 @@ minstrel_ht_stats_open(struct inode *inode, struct file *file)
 
 	p += sprintf(p, "\n");
 	p += sprintf(p,
-		     "              best   ____________rate__________    ____statistics___    _____last____    ______sum-of________\n");
+		     "              best    ____________rate__________    ____statistics___    _____last____    ______sum-of________\n");
 	p += sprintf(p,
-		     "mode guard #  rate  [name   idx airtime  max_tp]  [avg(tp) avg(prob)]  [retry|suc|att]  [#success | #attempts]\n");
+		     "mode guard #  rate   [name   idx airtime  max_tp]  [avg(tp) avg(prob)]  [retry|suc|att]  [#success | #attempts]\n");
 
 	p = minstrel_ht_stats_dump(mi, MINSTREL_CCK_GROUP, p);
 	for (i = 0; i < MINSTREL_CCK_GROUP; i++)
@@ -228,6 +241,8 @@ minstrel_ht_stats_csv_dump(struct minstrel_ht_sta *mi, int i, char *p)
 		p += sprintf(p, "%s" ,((idx == mi->max_tp_rate[2]) ? "C" : ""));
 		p += sprintf(p, "%s" ,((idx == mi->max_tp_rate[3]) ? "D" : ""));
 		p += sprintf(p, "%s" ,((idx == mi->max_prob_rate) ? "P" : ""));
+		p += sprintf(p, "%s" ,((idx == mi->max_prob_rate) ? "P" : ""));
+		p += sprintf(p, "%s", (minstrel_ht_is_sample_rate(mi, idx) ? "S" : ""));
 
 		if (gflags & IEEE80211_TX_RC_MCS) {
 			p += sprintf(p, ",MCS%-2u,", (mg->streams - 1) * 8 + j);
-- 
2.28.0

[PATCH 6/6] mac80211: minstrel_ht: remove sample rate switching code for constrained devices

[Felix Fietkau]

This was added to mitigate the effects of too much sampling on devices that
use a static global fallback table instead of configurable multi-rate retry.
Now that the sampling algorithm is improved, this code path no longer performs
any better than the standard probing on affected devices.

Signed-off-by: Felix Fietkau <nbd@nbd.name>
---
 net/mac80211/rc80211_minstrel_ht.c | 95 ++----------------------------
 net/mac80211/rc80211_minstrel_ht.h | 17 +-----
 2 files changed, 9 insertions(+), 103 deletions(-)

diff --git a/net/mac80211/rc80211_minstrel_ht.c b/net/mac80211/rc80211_minstrel_ht.c
index 95e10c4b1539..8e9e30c468a6 100644
--- a/net/mac80211/rc80211_minstrel_ht.c
+++ b/net/mac80211/rc80211_minstrel_ht.c
@@ -648,27 +648,6 @@ __minstrel_ht_get_sample_rate(struct minstrel_ht_sta *mi,
 	return 0;
 }
 
-static void
-minstrel_ht_rate_sample_switch(struct minstrel_priv *mp,
-			       struct minstrel_ht_sta *mi)
-{
-	u16 rate;
-
-	/*
-	 * Use rate switching instead of probing packets for devices with
-	 * little control over retry fallback behavior
-	 */
-	if (mp->hw->max_rates > 1)
-		return;
-
-	rate = __minstrel_ht_get_sample_rate(mi, MINSTREL_SAMPLE_TYPE_INC);
-	if (!rate)
-		return;
-
-	mi->sample_rate = rate;
-	mi->sample_mode = MINSTREL_SAMPLE_ACTIVE;
-}
-
 static inline int
 minstrel_ewma(int old, int new, int weight)
 {
@@ -1012,8 +991,7 @@ minstrel_ht_refill_sample_rates(struct minstrel_ht_sta *mi)
  *    higher throughput rates, even if the probablity is a bit lower
  */
 static void
-minstrel_ht_update_stats(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
-			 bool sample)
+minstrel_ht_update_stats(struct minstrel_priv *mp, struct minstrel_ht_sta *mi)
 {
 	struct minstrel_mcs_group_data *mg;
 	struct minstrel_rate_stats *mrs;
@@ -1023,18 +1001,6 @@ minstrel_ht_update_stats(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
 	u16 index;
 	bool ht_supported = mi->sta->ht_cap.ht_supported;
 
-	mi->sample_mode = MINSTREL_SAMPLE_IDLE;
-
-	if (sample) {
-		mi->total_packets_cur = mi->total_packets -
-					mi->total_packets_last;
-		mi->total_packets_last = mi->total_packets;
-	}
-	if (!mp->sample_switch)
-		sample = false;
-	if (mi->total_packets_cur < SAMPLE_SWITCH_THR && mp->sample_switch != 1)
-	    sample = false;
-
 	if (mi->ampdu_packets > 0) {
 		if (!ieee80211_hw_check(mp->hw, TX_STATUS_NO_AMPDU_LEN))
 			mi->avg_ampdu_len = minstrel_ewma(mi->avg_ampdu_len,
@@ -1149,16 +1115,12 @@ minstrel_ht_update_stats(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
 	minstrel_ht_prob_rate_reduce_streams(mi);
 	minstrel_ht_refill_sample_rates(mi);
 
-	if (sample)
-		minstrel_ht_rate_sample_switch(mp, mi);
-
 #ifdef CONFIG_MAC80211_DEBUGFS
 	/* use fixed index if set */
 	if (mp->fixed_rate_idx != -1) {
 		for (i = 0; i < 4; i++)
 			mi->max_tp_rate[i] = mp->fixed_rate_idx;
 		mi->max_prob_rate = mp->fixed_rate_idx;
-		mi->sample_mode = MINSTREL_SAMPLE_IDLE;
 	}
 #endif
 
@@ -1248,11 +1210,10 @@ minstrel_ht_tx_status(void *priv, struct ieee80211_supported_band *sband,
 	struct ieee80211_tx_info *info = st->info;
 	struct minstrel_ht_sta *mi = priv_sta;
 	struct ieee80211_tx_rate *ar = info->status.rates;
-	struct minstrel_rate_stats *rate, *rate2, *rate_sample = NULL;
+	struct minstrel_rate_stats *rate, *rate2;
 	struct minstrel_priv *mp = priv;
 	u32 update_interval = mp->update_interval;
 	bool last, update = false;
-	bool sample_status = false;
 	int i;
 
 	/* This packet was aggregated but doesn't carry status info */
@@ -1279,49 +1240,18 @@ minstrel_ht_tx_status(void *priv, struct ieee80211_supported_band *sband,
 	mi->ampdu_packets++;
 	mi->ampdu_len += info->status.ampdu_len;
 
-	if (mi->sample_mode != MINSTREL_SAMPLE_IDLE)
-		rate_sample = minstrel_get_ratestats(mi, mi->sample_rate);
-
 	last = !minstrel_ht_txstat_valid(mp, mi, &ar[0]);
 	for (i = 0; !last; i++) {
 		last = (i == IEEE80211_TX_MAX_RATES - 1) ||
 		       !minstrel_ht_txstat_valid(mp, mi, &ar[i + 1]);
 
 		rate = minstrel_ht_get_stats(mp, mi, &ar[i]);
-		if (rate == rate_sample)
-			sample_status = true;
-
 		if (last)
 			rate->success += info->status.ampdu_ack_len;
 
 		rate->attempts += ar[i].count * info->status.ampdu_len;
 	}
 
-	switch (mi->sample_mode) {
-	case MINSTREL_SAMPLE_IDLE:
-		if (mp->hw->max_rates > 1 ||
-		     mi->total_packets_cur < SAMPLE_SWITCH_THR)
-			update_interval /= 2;
-		break;
-
-	case MINSTREL_SAMPLE_ACTIVE:
-		if (!sample_status)
-			break;
-
-		mi->sample_mode = MINSTREL_SAMPLE_PENDING;
-		update = true;
-		break;
-
-	case MINSTREL_SAMPLE_PENDING:
-		if (sample_status)
-			break;
-
-		update = true;
-		minstrel_ht_update_stats(mp, mi, false);
-		break;
-	}
-
-
 	if (mp->hw->max_rates > 1) {
 		/*
 		 * check for sudden death of spatial multiplexing,
@@ -1344,7 +1274,7 @@ minstrel_ht_tx_status(void *priv, struct ieee80211_supported_band *sband,
 
 	if (time_after(jiffies, mi->last_stats_update + update_interval)) {
 		update = true;
-		minstrel_ht_update_stats(mp, mi, true);
+		minstrel_ht_update_stats(mp, mi);
 	}
 
 	if (update)
@@ -1523,18 +1453,14 @@ static void
 minstrel_ht_update_rates(struct minstrel_priv *mp, struct minstrel_ht_sta *mi)
 {
 	struct ieee80211_sta_rates *rates;
-	u16 first_rate = mi->max_tp_rate[0];
 	int i = 0;
 
-	if (mi->sample_mode == MINSTREL_SAMPLE_ACTIVE)
-		first_rate = mi->sample_rate;
-
 	rates = kzalloc(sizeof(*rates), GFP_ATOMIC);
 	if (!rates)
 		return;
 
 	/* Start with max_tp_rate[0] */
-	minstrel_ht_set_rate(mp, mi, rates, i++, first_rate);
+	minstrel_ht_set_rate(mp, mi, rates, i++, mi->max_tp_rate[0]);
 
 	if (mp->hw->max_rates >= 3) {
 		/* At least 3 tx rates supported, use max_tp_rate[1] next */
@@ -1593,11 +1519,6 @@ minstrel_ht_get_rate(void *priv, struct ieee80211_sta *sta, void *priv_sta,
 	    (info->control.flags & IEEE80211_TX_CTRL_PORT_CTRL_PROTO))
 		return;
 
-	if (mp->hw->max_rates == 1 && mp->sample_switch &&
-	    (mi->total_packets_cur >= SAMPLE_SWITCH_THR ||
-	     mp->sample_switch == 1))
-		return;
-
 	if (time_is_before_jiffies(mi->sample_time))
 		return;
 
@@ -1811,7 +1732,7 @@ minstrel_ht_update_caps(void *priv, struct ieee80211_supported_band *sband,
 	minstrel_ht_update_ofdm(mp, mi, sband, sta);
 
 	/* create an initial rate table with the lowest supported rates */
-	minstrel_ht_update_stats(mp, mi, true);
+	minstrel_ht_update_stats(mp, mi);
 	minstrel_ht_update_rates(mp, mi);
 }
 
@@ -1927,8 +1848,6 @@ minstrel_ht_alloc(struct ieee80211_hw *hw)
 	if (!mp)
 		return NULL;
 
-	mp->sample_switch = -1;
-
 	/* contention window settings
 	 * Just an approximation. Using the per-queue values would complicate
 	 * the calculations and is probably unnecessary */
@@ -1948,7 +1867,7 @@ minstrel_ht_alloc(struct ieee80211_hw *hw)
 		mp->has_mrr = true;
 
 	mp->hw = hw;
-	mp->update_interval = HZ / 10;
+	mp->update_interval = HZ / 20;
 
 	minstrel_ht_init_cck_rates(mp);
 	for (i = 0; i < ARRAY_SIZE(mp->hw->wiphy->bands); i++)
@@ -1966,8 +1885,6 @@ static void minstrel_ht_add_debugfs(struct ieee80211_hw *hw, void *priv,
 	mp->fixed_rate_idx = (u32) -1;
 	debugfs_create_u32("fixed_rate_idx", S_IRUGO | S_IWUGO, debugfsdir,
 			   &mp->fixed_rate_idx);
-	debugfs_create_u32("sample_switch", S_IRUGO | S_IWUSR, debugfsdir,
-			   &mp->sample_switch);
 }
 #endif
 
diff --git a/net/mac80211/rc80211_minstrel_ht.h b/net/mac80211/rc80211_minstrel_ht.h
index 0d8c15f83f5d..06e7126727ad 100644
--- a/net/mac80211/rc80211_minstrel_ht.h
+++ b/net/mac80211/rc80211_minstrel_ht.h
@@ -75,7 +75,6 @@
 struct minstrel_priv {
 	struct ieee80211_hw *hw;
 	bool has_mrr;
-	u32 sample_switch;
 	unsigned int cw_min;
 	unsigned int cw_max;
 	unsigned int max_retry;
@@ -147,12 +146,6 @@ struct minstrel_mcs_group_data {
 	struct minstrel_rate_stats rates[MCS_GROUP_RATES];
 };
 
-enum minstrel_sample_mode {
-	MINSTREL_SAMPLE_IDLE,
-	MINSTREL_SAMPLE_ACTIVE,
-	MINSTREL_SAMPLE_PENDING,
-};
-
 struct minstrel_sample_category {
 	u8 sample_group;
 	u16 sample_rates[MINSTREL_SAMPLE_RATES];
@@ -182,23 +175,19 @@ struct minstrel_ht_sta {
 	unsigned int overhead_legacy;
 	unsigned int overhead_legacy_rtscts;
 
-	unsigned int total_packets_last;
-	unsigned int total_packets_cur;
 	unsigned int total_packets;
 	unsigned int sample_packets;
 
 	/* tx flags to add for frames for this sta */
 	u32 tx_flags;
 
-	unsigned long sample_time;
-	struct minstrel_sample_category sample[__MINSTREL_SAMPLE_TYPE_MAX];
+	u8 band;
 
 	u8 sample_seq;
-
-	enum minstrel_sample_mode sample_mode;
 	u16 sample_rate;
 
-	u8 band;
+	unsigned long sample_time;
+	struct minstrel_sample_category sample[__MINSTREL_SAMPLE_TYPE_MAX];
 
 	/* Bitfield of supported MCS rates of all groups */
 	u16 supported[MINSTREL_GROUPS_NB];
-- 
2.28.0

Re: [PATCH 1/6] mac80211: minstrel_ht: use bitfields to encode rate indexes

[kernel test robot]

[-- Attachment #1: Type: text/plain, Size: 14496 bytes --]

Hi Felix,

I love your patch! Perhaps something to improve:

[auto build test WARNING on mac80211-next/master]
[also build test WARNING on next-20210125]
[cannot apply to mac80211/master v5.11-rc5]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:    https://github.com/0day-ci/linux/commits/Felix-Fietkau/mac80211-minstrel_ht-use-bitfields-to-encode-rate-indexes/20210125-210635
base:   https://git.kernel.org/pub/scm/linux/kernel/git/jberg/mac80211-next.git master
config: x86_64-randconfig-a015-20210125 (attached as .config)
compiler: clang version 12.0.0 (https://github.com/llvm/llvm-project 12d0753aca22896fda2cf76781b0ee0524d55065)
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # install x86_64 cross compiling tool for clang build
        # apt-get install binutils-x86-64-linux-gnu
        # https://github.com/0day-ci/linux/commit/8a2d01887013f71806262345f71766d6518e3552
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Felix-Fietkau/mac80211-minstrel_ht-use-bitfields-to-encode-rate-indexes/20210125-210635
        git checkout 8a2d01887013f71806262345f71766d6518e3552
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=x86_64 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All warnings (new ones prefixed by >>):

>> net/mac80211/rc80211_minstrel_ht.c:862:11: warning: variable 'group' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]
           else if (mi->supported[MINSTREL_OFDM_GROUP])
                    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   net/mac80211/rc80211_minstrel_ht.c:865:18: note: uninitialized use occurs here
           index = MI_RATE(group, 0);
                           ^~~~~
   net/mac80211/rc80211_minstrel_ht.h:66:34: note: expanded from macro 'MI_RATE'
           (FIELD_PREP(MI_RATE_GROUP_MASK, _group) |       \
                                           ^~~~~~
   include/linux/bitfield.h:95:20: note: expanded from macro 'FIELD_PREP'
                   ((typeof(_mask))(_val) << __bf_shf(_mask)) & (_mask);   \
                                    ^~~~
   net/mac80211/rc80211_minstrel_ht.c:862:7: note: remove the 'if' if its condition is always true
           else if (mi->supported[MINSTREL_OFDM_GROUP])
                ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   net/mac80211/rc80211_minstrel_ht.c:825:11: note: initialize the variable 'group' to silence this warning
           int group, i, j, cur_prob;
                    ^
                     = 0
   1 warning generated.


vim +862 net/mac80211/rc80211_minstrel_ht.c

cbda98c710d273b Felix Fietkau 2021-01-15  809  
ec8aa669b8393b6 Felix Fietkau 2010-05-13  810  /*
ec8aa669b8393b6 Felix Fietkau 2010-05-13  811   * Update rate statistics and select new primary rates
ec8aa669b8393b6 Felix Fietkau 2010-05-13  812   *
ec8aa669b8393b6 Felix Fietkau 2010-05-13  813   * Rules for rate selection:
ec8aa669b8393b6 Felix Fietkau 2010-05-13  814   *  - max_prob_rate must use only one stream, as a tradeoff between delivery
ec8aa669b8393b6 Felix Fietkau 2010-05-13  815   *    probability and throughput during strong fluctuations
5935839ad735837 Thomas Huehn  2014-09-09  816   *  - as long as the max prob rate has a probability of more than 75%, pick
ec8aa669b8393b6 Felix Fietkau 2010-05-13  817   *    higher throughput rates, even if the probablity is a bit lower
ec8aa669b8393b6 Felix Fietkau 2010-05-13  818   */
ec8aa669b8393b6 Felix Fietkau 2010-05-13  819  static void
48cb39522a9d4d4 Felix Fietkau 2019-08-20  820  minstrel_ht_update_stats(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
48cb39522a9d4d4 Felix Fietkau 2019-08-20  821  			 bool sample)
ec8aa669b8393b6 Felix Fietkau 2010-05-13  822  {
ec8aa669b8393b6 Felix Fietkau 2010-05-13  823  	struct minstrel_mcs_group_data *mg;
9134073bc693633 Thomas Huehn  2015-03-24  824  	struct minstrel_rate_stats *mrs;
50e55a8ea76fb59 Thomas Huehn  2015-03-24  825  	int group, i, j, cur_prob;
d4d141cae804a43 Karl Beldan   2014-10-20  826  	u16 tmp_mcs_tp_rate[MAX_THR_RATES], tmp_group_tp_rate[MAX_THR_RATES];
a7fca4e4037f7e3 Felix Fietkau 2021-01-15  827  	u16 tmp_legacy_tp_rate[MAX_THR_RATES], tmp_max_prob_rate;
a7fca4e4037f7e3 Felix Fietkau 2021-01-15  828  	u16 index;
a7844a53846017c Felix Fietkau 2021-01-15  829  	bool ht_supported = mi->sta->ht_cap.ht_supported;
ec8aa669b8393b6 Felix Fietkau 2010-05-13  830  
48cb39522a9d4d4 Felix Fietkau 2019-08-20  831  	mi->sample_mode = MINSTREL_SAMPLE_IDLE;
48cb39522a9d4d4 Felix Fietkau 2019-08-20  832  
48cb39522a9d4d4 Felix Fietkau 2019-08-20  833  	if (sample) {
48cb39522a9d4d4 Felix Fietkau 2019-08-20  834  		mi->total_packets_cur = mi->total_packets -
48cb39522a9d4d4 Felix Fietkau 2019-08-20  835  					mi->total_packets_last;
48cb39522a9d4d4 Felix Fietkau 2019-08-20  836  		mi->total_packets_last = mi->total_packets;
48cb39522a9d4d4 Felix Fietkau 2019-08-20  837  	}
48cb39522a9d4d4 Felix Fietkau 2019-08-20  838  	if (!mp->sample_switch)
48cb39522a9d4d4 Felix Fietkau 2019-08-20  839  		sample = false;
48cb39522a9d4d4 Felix Fietkau 2019-08-20  840  	if (mi->total_packets_cur < SAMPLE_SWITCH_THR && mp->sample_switch != 1)
48cb39522a9d4d4 Felix Fietkau 2019-08-20  841  	    sample = false;
48cb39522a9d4d4 Felix Fietkau 2019-08-20  842  
ec8aa669b8393b6 Felix Fietkau 2010-05-13  843  	if (mi->ampdu_packets > 0) {
77f7ffdc335de85 Felix Fietkau 2019-01-16  844  		if (!ieee80211_hw_check(mp->hw, TX_STATUS_NO_AMPDU_LEN))
ec8aa669b8393b6 Felix Fietkau 2010-05-13  845  			mi->avg_ampdu_len = minstrel_ewma(mi->avg_ampdu_len,
77f7ffdc335de85 Felix Fietkau 2019-01-16  846  				MINSTREL_FRAC(mi->ampdu_len, mi->ampdu_packets),
77f7ffdc335de85 Felix Fietkau 2019-01-16  847  					      EWMA_LEVEL);
77f7ffdc335de85 Felix Fietkau 2019-01-16  848  		else
77f7ffdc335de85 Felix Fietkau 2019-01-16  849  			mi->avg_ampdu_len = 0;
ec8aa669b8393b6 Felix Fietkau 2010-05-13  850  		mi->ampdu_len = 0;
ec8aa669b8393b6 Felix Fietkau 2010-05-13  851  		mi->ampdu_packets = 0;
ec8aa669b8393b6 Felix Fietkau 2010-05-13  852  	}
ec8aa669b8393b6 Felix Fietkau 2010-05-13  853  
ec8aa669b8393b6 Felix Fietkau 2010-05-13  854  	mi->sample_slow = 0;
ec8aa669b8393b6 Felix Fietkau 2010-05-13  855  	mi->sample_count = 0;
ec8aa669b8393b6 Felix Fietkau 2010-05-13  856  
21f7981b4bd9048 Felix Fietkau 2019-08-20  857  	memset(tmp_mcs_tp_rate, 0, sizeof(tmp_mcs_tp_rate));
a7844a53846017c Felix Fietkau 2021-01-15  858  	memset(tmp_legacy_tp_rate, 0, sizeof(tmp_legacy_tp_rate));
8a2d01887013f71 Felix Fietkau 2021-01-24  859  
21f7981b4bd9048 Felix Fietkau 2019-08-20  860  	if (mi->supported[MINSTREL_CCK_GROUP])
8a2d01887013f71 Felix Fietkau 2021-01-24  861  		group = MINSTREL_CCK_GROUP;
a7844a53846017c Felix Fietkau 2021-01-15 @862  	else if (mi->supported[MINSTREL_OFDM_GROUP])
8a2d01887013f71 Felix Fietkau 2021-01-24  863  		group = MINSTREL_OFDM_GROUP;
8a2d01887013f71 Felix Fietkau 2021-01-24  864  
8a2d01887013f71 Felix Fietkau 2021-01-24  865  	index = MI_RATE(group, 0);
a7844a53846017c Felix Fietkau 2021-01-15  866  	for (j = 0; j < ARRAY_SIZE(tmp_legacy_tp_rate); j++)
8a2d01887013f71 Felix Fietkau 2021-01-24  867  		tmp_legacy_tp_rate[j] = index;
21f7981b4bd9048 Felix Fietkau 2019-08-20  868  
21f7981b4bd9048 Felix Fietkau 2019-08-20  869  	if (mi->supported[MINSTREL_VHT_GROUP_0])
8a2d01887013f71 Felix Fietkau 2021-01-24  870  		group = MINSTREL_VHT_GROUP_0;
a7844a53846017c Felix Fietkau 2021-01-15  871  	else if (ht_supported)
8a2d01887013f71 Felix Fietkau 2021-01-24  872  		group = MINSTREL_HT_GROUP_0;
a7844a53846017c Felix Fietkau 2021-01-15  873  	else if (mi->supported[MINSTREL_CCK_GROUP])
8a2d01887013f71 Felix Fietkau 2021-01-24  874  		group = MINSTREL_CCK_GROUP;
a7844a53846017c Felix Fietkau 2021-01-15  875  	else
8a2d01887013f71 Felix Fietkau 2021-01-24  876  		group = MINSTREL_OFDM_GROUP;
21f7981b4bd9048 Felix Fietkau 2019-08-20  877  
8a2d01887013f71 Felix Fietkau 2021-01-24  878  	index = MI_RATE(group, 0);
a7fca4e4037f7e3 Felix Fietkau 2021-01-15  879  	tmp_max_prob_rate = index;
21f7981b4bd9048 Felix Fietkau 2019-08-20  880  	for (j = 0; j < ARRAY_SIZE(tmp_mcs_tp_rate); j++)
21f7981b4bd9048 Felix Fietkau 2019-08-20  881  		tmp_mcs_tp_rate[j] = index;
c2eb5b0f342c9b1 Karl Beldan   2013-04-18  882  
5935839ad735837 Thomas Huehn  2014-09-09  883  	/* Find best rate sets within all MCS groups*/
5935839ad735837 Thomas Huehn  2014-09-09  884  	for (group = 0; group < ARRAY_SIZE(minstrel_mcs_groups); group++) {
a7844a53846017c Felix Fietkau 2021-01-15  885  		u16 *tp_rate = tmp_mcs_tp_rate;
ec8aa669b8393b6 Felix Fietkau 2010-05-13  886  
ec8aa669b8393b6 Felix Fietkau 2010-05-13  887  		mg = &mi->groups[group];
41d085835d3d225 Felix Fietkau 2016-12-14  888  		if (!mi->supported[group])
ec8aa669b8393b6 Felix Fietkau 2010-05-13  889  			continue;
ec8aa669b8393b6 Felix Fietkau 2010-05-13  890  
ec8aa669b8393b6 Felix Fietkau 2010-05-13  891  		mi->sample_count++;
ec8aa669b8393b6 Felix Fietkau 2010-05-13  892  
5935839ad735837 Thomas Huehn  2014-09-09  893  		/* (re)Initialize group rate indexes */
5935839ad735837 Thomas Huehn  2014-09-09  894  		for(j = 0; j < MAX_THR_RATES; j++)
8a2d01887013f71 Felix Fietkau 2021-01-24  895  			tmp_group_tp_rate[j] = MI_RATE(group, 0);
5935839ad735837 Thomas Huehn  2014-09-09  896  
a7844a53846017c Felix Fietkau 2021-01-15  897  		if (group == MINSTREL_CCK_GROUP && ht_supported)
a7844a53846017c Felix Fietkau 2021-01-15  898  			tp_rate = tmp_legacy_tp_rate;
a7844a53846017c Felix Fietkau 2021-01-15  899  
ec8aa669b8393b6 Felix Fietkau 2010-05-13  900  		for (i = 0; i < MCS_GROUP_RATES; i++) {
41d085835d3d225 Felix Fietkau 2016-12-14  901  			if (!(mi->supported[group] & BIT(i)))
ec8aa669b8393b6 Felix Fietkau 2010-05-13  902  				continue;
ec8aa669b8393b6 Felix Fietkau 2010-05-13  903  
8a2d01887013f71 Felix Fietkau 2021-01-24  904  			index = MI_RATE(group, i);
351df099721e02e Karl Beldan   2013-11-13  905  
9134073bc693633 Thomas Huehn  2015-03-24  906  			mrs = &mg->rates[i];
9134073bc693633 Thomas Huehn  2015-03-24  907  			mrs->retry_updated = false;
cbda98c710d273b Felix Fietkau 2021-01-15  908  			minstrel_ht_calc_rate_stats(mp, mrs);
5f63afe0288d955 Felix Fietkau 2019-10-08  909  			cur_prob = mrs->prob_avg;
ec8aa669b8393b6 Felix Fietkau 2010-05-13  910  
50e55a8ea76fb59 Thomas Huehn  2015-03-24  911  			if (minstrel_ht_get_tp_avg(mi, group, i, cur_prob) == 0)
ec8aa669b8393b6 Felix Fietkau 2010-05-13  912  				continue;
ec8aa669b8393b6 Felix Fietkau 2010-05-13  913  
5935839ad735837 Thomas Huehn  2014-09-09  914  			/* Find max throughput rate set */
a7844a53846017c Felix Fietkau 2021-01-15  915  			minstrel_ht_sort_best_tp_rates(mi, index, tp_rate);
ec8aa669b8393b6 Felix Fietkau 2010-05-13  916  
5935839ad735837 Thomas Huehn  2014-09-09  917  			/* Find max throughput rate set within a group */
5935839ad735837 Thomas Huehn  2014-09-09  918  			minstrel_ht_sort_best_tp_rates(mi, index,
5935839ad735837 Thomas Huehn  2014-09-09  919  						       tmp_group_tp_rate);
ec8aa669b8393b6 Felix Fietkau 2010-05-13  920  		}
ec8aa669b8393b6 Felix Fietkau 2010-05-13  921  
5935839ad735837 Thomas Huehn  2014-09-09  922  		memcpy(mg->max_group_tp_rate, tmp_group_tp_rate,
5935839ad735837 Thomas Huehn  2014-09-09  923  		       sizeof(mg->max_group_tp_rate));
ec8aa669b8393b6 Felix Fietkau 2010-05-13  924  	}
ec8aa669b8393b6 Felix Fietkau 2010-05-13  925  
5935839ad735837 Thomas Huehn  2014-09-09  926  	/* Assign new rate set per sta */
a7844a53846017c Felix Fietkau 2021-01-15  927  	minstrel_ht_assign_best_tp_rates(mi, tmp_mcs_tp_rate,
a7844a53846017c Felix Fietkau 2021-01-15  928  					 tmp_legacy_tp_rate);
5935839ad735837 Thomas Huehn  2014-09-09  929  	memcpy(mi->max_tp_rate, tmp_mcs_tp_rate, sizeof(mi->max_tp_rate));
ec8aa669b8393b6 Felix Fietkau 2010-05-13  930  
a7fca4e4037f7e3 Felix Fietkau 2021-01-15  931  	for (group = 0; group < ARRAY_SIZE(minstrel_mcs_groups); group++) {
a7fca4e4037f7e3 Felix Fietkau 2021-01-15  932  		if (!mi->supported[group])
a7fca4e4037f7e3 Felix Fietkau 2021-01-15  933  			continue;
a7fca4e4037f7e3 Felix Fietkau 2021-01-15  934  
a7fca4e4037f7e3 Felix Fietkau 2021-01-15  935  		mg = &mi->groups[group];
8a2d01887013f71 Felix Fietkau 2021-01-24  936  		mg->max_group_prob_rate = MI_RATE(group, 0);
a7fca4e4037f7e3 Felix Fietkau 2021-01-15  937  
a7fca4e4037f7e3 Felix Fietkau 2021-01-15  938  		for (i = 0; i < MCS_GROUP_RATES; i++) {
a7fca4e4037f7e3 Felix Fietkau 2021-01-15  939  			if (!(mi->supported[group] & BIT(i)))
a7fca4e4037f7e3 Felix Fietkau 2021-01-15  940  				continue;
a7fca4e4037f7e3 Felix Fietkau 2021-01-15  941  
8a2d01887013f71 Felix Fietkau 2021-01-24  942  			index = MI_RATE(group, i);
a7fca4e4037f7e3 Felix Fietkau 2021-01-15  943  
a7fca4e4037f7e3 Felix Fietkau 2021-01-15  944  			/* Find max probability rate per group and global */
a7fca4e4037f7e3 Felix Fietkau 2021-01-15  945  			minstrel_ht_set_best_prob_rate(mi, &tmp_max_prob_rate,
a7fca4e4037f7e3 Felix Fietkau 2021-01-15  946  						       index);
a7fca4e4037f7e3 Felix Fietkau 2021-01-15  947  		}
a7fca4e4037f7e3 Felix Fietkau 2021-01-15  948  	}
a7fca4e4037f7e3 Felix Fietkau 2021-01-15  949  
a7fca4e4037f7e3 Felix Fietkau 2021-01-15  950  	mi->max_prob_rate = tmp_max_prob_rate;
a7fca4e4037f7e3 Felix Fietkau 2021-01-15  951  
5935839ad735837 Thomas Huehn  2014-09-09  952  	/* Try to increase robustness of max_prob_rate*/
5935839ad735837 Thomas Huehn  2014-09-09  953  	minstrel_ht_prob_rate_reduce_streams(mi);
a299c6d591f8f6a Felix Fietkau 2013-03-02  954  
eeafcb0c80c81d6 Felix Fietkau 2021-01-15  955  	/* try to sample half of all available rates during each interval */
eeafcb0c80c81d6 Felix Fietkau 2021-01-15  956  	mi->sample_count *= 4;
a299c6d591f8f6a Felix Fietkau 2013-03-02  957  
48cb39522a9d4d4 Felix Fietkau 2019-08-20  958  	if (sample)
48cb39522a9d4d4 Felix Fietkau 2019-08-20  959  		minstrel_ht_rate_sample_switch(mp, mi);
48cb39522a9d4d4 Felix Fietkau 2019-08-20  960  

---
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https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org

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Re: [PATCH 1/6] mac80211: minstrel_ht: use bitfields to encode rate indexes

[kernel test robot]

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Hi Felix,

I love your patch! Perhaps something to improve:

[auto build test WARNING on mac80211-next/master]
[also build test WARNING on next-20210125]
[cannot apply to mac80211/master v5.11-rc5]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:    https://github.com/0day-ci/linux/commits/Felix-Fietkau/mac80211-minstrel_ht-use-bitfields-to-encode-rate-indexes/20210125-210635
base:   https://git.kernel.org/pub/scm/linux/kernel/git/jberg/mac80211-next.git master
config: x86_64-randconfig-a015-20210125 (attached as .config)
compiler: clang version 12.0.0 (https://github.com/llvm/llvm-project 12d0753aca22896fda2cf76781b0ee0524d55065)
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # install x86_64 cross compiling tool for clang build
        # apt-get install binutils-x86-64-linux-gnu
        # https://github.com/0day-ci/linux/commit/8a2d01887013f71806262345f71766d6518e3552
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Felix-Fietkau/mac80211-minstrel_ht-use-bitfields-to-encode-rate-indexes/20210125-210635
        git checkout 8a2d01887013f71806262345f71766d6518e3552
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=x86_64 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All warnings (new ones prefixed by >>):

>> net/mac80211/rc80211_minstrel_ht.c:862:11: warning: variable 'group' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]
           else if (mi->supported[MINSTREL_OFDM_GROUP])
                    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   net/mac80211/rc80211_minstrel_ht.c:865:18: note: uninitialized use occurs here
           index = MI_RATE(group, 0);
                           ^~~~~
   net/mac80211/rc80211_minstrel_ht.h:66:34: note: expanded from macro 'MI_RATE'
           (FIELD_PREP(MI_RATE_GROUP_MASK, _group) |       \
                                           ^~~~~~
   include/linux/bitfield.h:95:20: note: expanded from macro 'FIELD_PREP'
                   ((typeof(_mask))(_val) << __bf_shf(_mask)) & (_mask);   \
                                    ^~~~
   net/mac80211/rc80211_minstrel_ht.c:862:7: note: remove the 'if' if its condition is always true
           else if (mi->supported[MINSTREL_OFDM_GROUP])
                ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   net/mac80211/rc80211_minstrel_ht.c:825:11: note: initialize the variable 'group' to silence this warning
           int group, i, j, cur_prob;
                    ^
                     = 0
   1 warning generated.


vim +862 net/mac80211/rc80211_minstrel_ht.c

cbda98c710d273b Felix Fietkau 2021-01-15  809  
ec8aa669b8393b6 Felix Fietkau 2010-05-13  810  /*
ec8aa669b8393b6 Felix Fietkau 2010-05-13  811   * Update rate statistics and select new primary rates
ec8aa669b8393b6 Felix Fietkau 2010-05-13  812   *
ec8aa669b8393b6 Felix Fietkau 2010-05-13  813   * Rules for rate selection:
ec8aa669b8393b6 Felix Fietkau 2010-05-13  814   *  - max_prob_rate must use only one stream, as a tradeoff between delivery
ec8aa669b8393b6 Felix Fietkau 2010-05-13  815   *    probability and throughput during strong fluctuations
5935839ad735837 Thomas Huehn  2014-09-09  816   *  - as long as the max prob rate has a probability of more than 75%, pick
ec8aa669b8393b6 Felix Fietkau 2010-05-13  817   *    higher throughput rates, even if the probablity is a bit lower
ec8aa669b8393b6 Felix Fietkau 2010-05-13  818   */
ec8aa669b8393b6 Felix Fietkau 2010-05-13  819  static void
48cb39522a9d4d4 Felix Fietkau 2019-08-20  820  minstrel_ht_update_stats(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
48cb39522a9d4d4 Felix Fietkau 2019-08-20  821  			 bool sample)
ec8aa669b8393b6 Felix Fietkau 2010-05-13  822  {
ec8aa669b8393b6 Felix Fietkau 2010-05-13  823  	struct minstrel_mcs_group_data *mg;
9134073bc693633 Thomas Huehn  2015-03-24  824  	struct minstrel_rate_stats *mrs;
50e55a8ea76fb59 Thomas Huehn  2015-03-24  825  	int group, i, j, cur_prob;
d4d141cae804a43 Karl Beldan   2014-10-20  826  	u16 tmp_mcs_tp_rate[MAX_THR_RATES], tmp_group_tp_rate[MAX_THR_RATES];
a7fca4e4037f7e3 Felix Fietkau 2021-01-15  827  	u16 tmp_legacy_tp_rate[MAX_THR_RATES], tmp_max_prob_rate;
a7fca4e4037f7e3 Felix Fietkau 2021-01-15  828  	u16 index;
a7844a53846017c Felix Fietkau 2021-01-15  829  	bool ht_supported = mi->sta->ht_cap.ht_supported;
ec8aa669b8393b6 Felix Fietkau 2010-05-13  830  
48cb39522a9d4d4 Felix Fietkau 2019-08-20  831  	mi->sample_mode = MINSTREL_SAMPLE_IDLE;
48cb39522a9d4d4 Felix Fietkau 2019-08-20  832  
48cb39522a9d4d4 Felix Fietkau 2019-08-20  833  	if (sample) {
48cb39522a9d4d4 Felix Fietkau 2019-08-20  834  		mi->total_packets_cur = mi->total_packets -
48cb39522a9d4d4 Felix Fietkau 2019-08-20  835  					mi->total_packets_last;
48cb39522a9d4d4 Felix Fietkau 2019-08-20  836  		mi->total_packets_last = mi->total_packets;
48cb39522a9d4d4 Felix Fietkau 2019-08-20  837  	}
48cb39522a9d4d4 Felix Fietkau 2019-08-20  838  	if (!mp->sample_switch)
48cb39522a9d4d4 Felix Fietkau 2019-08-20  839  		sample = false;
48cb39522a9d4d4 Felix Fietkau 2019-08-20  840  	if (mi->total_packets_cur < SAMPLE_SWITCH_THR && mp->sample_switch != 1)
48cb39522a9d4d4 Felix Fietkau 2019-08-20  841  	    sample = false;
48cb39522a9d4d4 Felix Fietkau 2019-08-20  842  
ec8aa669b8393b6 Felix Fietkau 2010-05-13  843  	if (mi->ampdu_packets > 0) {
77f7ffdc335de85 Felix Fietkau 2019-01-16  844  		if (!ieee80211_hw_check(mp->hw, TX_STATUS_NO_AMPDU_LEN))
ec8aa669b8393b6 Felix Fietkau 2010-05-13  845  			mi->avg_ampdu_len = minstrel_ewma(mi->avg_ampdu_len,
77f7ffdc335de85 Felix Fietkau 2019-01-16  846  				MINSTREL_FRAC(mi->ampdu_len, mi->ampdu_packets),
77f7ffdc335de85 Felix Fietkau 2019-01-16  847  					      EWMA_LEVEL);
77f7ffdc335de85 Felix Fietkau 2019-01-16  848  		else
77f7ffdc335de85 Felix Fietkau 2019-01-16  849  			mi->avg_ampdu_len = 0;
ec8aa669b8393b6 Felix Fietkau 2010-05-13  850  		mi->ampdu_len = 0;
ec8aa669b8393b6 Felix Fietkau 2010-05-13  851  		mi->ampdu_packets = 0;
ec8aa669b8393b6 Felix Fietkau 2010-05-13  852  	}
ec8aa669b8393b6 Felix Fietkau 2010-05-13  853  
ec8aa669b8393b6 Felix Fietkau 2010-05-13  854  	mi->sample_slow = 0;
ec8aa669b8393b6 Felix Fietkau 2010-05-13  855  	mi->sample_count = 0;
ec8aa669b8393b6 Felix Fietkau 2010-05-13  856  
21f7981b4bd9048 Felix Fietkau 2019-08-20  857  	memset(tmp_mcs_tp_rate, 0, sizeof(tmp_mcs_tp_rate));
a7844a53846017c Felix Fietkau 2021-01-15  858  	memset(tmp_legacy_tp_rate, 0, sizeof(tmp_legacy_tp_rate));
8a2d01887013f71 Felix Fietkau 2021-01-24  859  
21f7981b4bd9048 Felix Fietkau 2019-08-20  860  	if (mi->supported[MINSTREL_CCK_GROUP])
8a2d01887013f71 Felix Fietkau 2021-01-24  861  		group = MINSTREL_CCK_GROUP;
a7844a53846017c Felix Fietkau 2021-01-15 @862  	else if (mi->supported[MINSTREL_OFDM_GROUP])
8a2d01887013f71 Felix Fietkau 2021-01-24  863  		group = MINSTREL_OFDM_GROUP;
8a2d01887013f71 Felix Fietkau 2021-01-24  864  
8a2d01887013f71 Felix Fietkau 2021-01-24  865  	index = MI_RATE(group, 0);
a7844a53846017c Felix Fietkau 2021-01-15  866  	for (j = 0; j < ARRAY_SIZE(tmp_legacy_tp_rate); j++)
8a2d01887013f71 Felix Fietkau 2021-01-24  867  		tmp_legacy_tp_rate[j] = index;
21f7981b4bd9048 Felix Fietkau 2019-08-20  868  
21f7981b4bd9048 Felix Fietkau 2019-08-20  869  	if (mi->supported[MINSTREL_VHT_GROUP_0])
8a2d01887013f71 Felix Fietkau 2021-01-24  870  		group = MINSTREL_VHT_GROUP_0;
a7844a53846017c Felix Fietkau 2021-01-15  871  	else if (ht_supported)
8a2d01887013f71 Felix Fietkau 2021-01-24  872  		group = MINSTREL_HT_GROUP_0;
a7844a53846017c Felix Fietkau 2021-01-15  873  	else if (mi->supported[MINSTREL_CCK_GROUP])
8a2d01887013f71 Felix Fietkau 2021-01-24  874  		group = MINSTREL_CCK_GROUP;
a7844a53846017c Felix Fietkau 2021-01-15  875  	else
8a2d01887013f71 Felix Fietkau 2021-01-24  876  		group = MINSTREL_OFDM_GROUP;
21f7981b4bd9048 Felix Fietkau 2019-08-20  877  
8a2d01887013f71 Felix Fietkau 2021-01-24  878  	index = MI_RATE(group, 0);
a7fca4e4037f7e3 Felix Fietkau 2021-01-15  879  	tmp_max_prob_rate = index;
21f7981b4bd9048 Felix Fietkau 2019-08-20  880  	for (j = 0; j < ARRAY_SIZE(tmp_mcs_tp_rate); j++)
21f7981b4bd9048 Felix Fietkau 2019-08-20  881  		tmp_mcs_tp_rate[j] = index;
c2eb5b0f342c9b1 Karl Beldan   2013-04-18  882  
5935839ad735837 Thomas Huehn  2014-09-09  883  	/* Find best rate sets within all MCS groups*/
5935839ad735837 Thomas Huehn  2014-09-09  884  	for (group = 0; group < ARRAY_SIZE(minstrel_mcs_groups); group++) {
a7844a53846017c Felix Fietkau 2021-01-15  885  		u16 *tp_rate = tmp_mcs_tp_rate;
ec8aa669b8393b6 Felix Fietkau 2010-05-13  886  
ec8aa669b8393b6 Felix Fietkau 2010-05-13  887  		mg = &mi->groups[group];
41d085835d3d225 Felix Fietkau 2016-12-14  888  		if (!mi->supported[group])
ec8aa669b8393b6 Felix Fietkau 2010-05-13  889  			continue;
ec8aa669b8393b6 Felix Fietkau 2010-05-13  890  
ec8aa669b8393b6 Felix Fietkau 2010-05-13  891  		mi->sample_count++;
ec8aa669b8393b6 Felix Fietkau 2010-05-13  892  
5935839ad735837 Thomas Huehn  2014-09-09  893  		/* (re)Initialize group rate indexes */
5935839ad735837 Thomas Huehn  2014-09-09  894  		for(j = 0; j < MAX_THR_RATES; j++)
8a2d01887013f71 Felix Fietkau 2021-01-24  895  			tmp_group_tp_rate[j] = MI_RATE(group, 0);
5935839ad735837 Thomas Huehn  2014-09-09  896  
a7844a53846017c Felix Fietkau 2021-01-15  897  		if (group == MINSTREL_CCK_GROUP && ht_supported)
a7844a53846017c Felix Fietkau 2021-01-15  898  			tp_rate = tmp_legacy_tp_rate;
a7844a53846017c Felix Fietkau 2021-01-15  899  
ec8aa669b8393b6 Felix Fietkau 2010-05-13  900  		for (i = 0; i < MCS_GROUP_RATES; i++) {
41d085835d3d225 Felix Fietkau 2016-12-14  901  			if (!(mi->supported[group] & BIT(i)))
ec8aa669b8393b6 Felix Fietkau 2010-05-13  902  				continue;
ec8aa669b8393b6 Felix Fietkau 2010-05-13  903  
8a2d01887013f71 Felix Fietkau 2021-01-24  904  			index = MI_RATE(group, i);
351df099721e02e Karl Beldan   2013-11-13  905  
9134073bc693633 Thomas Huehn  2015-03-24  906  			mrs = &mg->rates[i];
9134073bc693633 Thomas Huehn  2015-03-24  907  			mrs->retry_updated = false;
cbda98c710d273b Felix Fietkau 2021-01-15  908  			minstrel_ht_calc_rate_stats(mp, mrs);
5f63afe0288d955 Felix Fietkau 2019-10-08  909  			cur_prob = mrs->prob_avg;
ec8aa669b8393b6 Felix Fietkau 2010-05-13  910  
50e55a8ea76fb59 Thomas Huehn  2015-03-24  911  			if (minstrel_ht_get_tp_avg(mi, group, i, cur_prob) == 0)
ec8aa669b8393b6 Felix Fietkau 2010-05-13  912  				continue;
ec8aa669b8393b6 Felix Fietkau 2010-05-13  913  
5935839ad735837 Thomas Huehn  2014-09-09  914  			/* Find max throughput rate set */
a7844a53846017c Felix Fietkau 2021-01-15  915  			minstrel_ht_sort_best_tp_rates(mi, index, tp_rate);
ec8aa669b8393b6 Felix Fietkau 2010-05-13  916  
5935839ad735837 Thomas Huehn  2014-09-09  917  			/* Find max throughput rate set within a group */
5935839ad735837 Thomas Huehn  2014-09-09  918  			minstrel_ht_sort_best_tp_rates(mi, index,
5935839ad735837 Thomas Huehn  2014-09-09  919  						       tmp_group_tp_rate);
ec8aa669b8393b6 Felix Fietkau 2010-05-13  920  		}
ec8aa669b8393b6 Felix Fietkau 2010-05-13  921  
5935839ad735837 Thomas Huehn  2014-09-09  922  		memcpy(mg->max_group_tp_rate, tmp_group_tp_rate,
5935839ad735837 Thomas Huehn  2014-09-09  923  		       sizeof(mg->max_group_tp_rate));
ec8aa669b8393b6 Felix Fietkau 2010-05-13  924  	}
ec8aa669b8393b6 Felix Fietkau 2010-05-13  925  
5935839ad735837 Thomas Huehn  2014-09-09  926  	/* Assign new rate set per sta */
a7844a53846017c Felix Fietkau 2021-01-15  927  	minstrel_ht_assign_best_tp_rates(mi, tmp_mcs_tp_rate,
a7844a53846017c Felix Fietkau 2021-01-15  928  					 tmp_legacy_tp_rate);
5935839ad735837 Thomas Huehn  2014-09-09  929  	memcpy(mi->max_tp_rate, tmp_mcs_tp_rate, sizeof(mi->max_tp_rate));
ec8aa669b8393b6 Felix Fietkau 2010-05-13  930  
a7fca4e4037f7e3 Felix Fietkau 2021-01-15  931  	for (group = 0; group < ARRAY_SIZE(minstrel_mcs_groups); group++) {
a7fca4e4037f7e3 Felix Fietkau 2021-01-15  932  		if (!mi->supported[group])
a7fca4e4037f7e3 Felix Fietkau 2021-01-15  933  			continue;
a7fca4e4037f7e3 Felix Fietkau 2021-01-15  934  
a7fca4e4037f7e3 Felix Fietkau 2021-01-15  935  		mg = &mi->groups[group];
8a2d01887013f71 Felix Fietkau 2021-01-24  936  		mg->max_group_prob_rate = MI_RATE(group, 0);
a7fca4e4037f7e3 Felix Fietkau 2021-01-15  937  
a7fca4e4037f7e3 Felix Fietkau 2021-01-15  938  		for (i = 0; i < MCS_GROUP_RATES; i++) {
a7fca4e4037f7e3 Felix Fietkau 2021-01-15  939  			if (!(mi->supported[group] & BIT(i)))
a7fca4e4037f7e3 Felix Fietkau 2021-01-15  940  				continue;
a7fca4e4037f7e3 Felix Fietkau 2021-01-15  941  
8a2d01887013f71 Felix Fietkau 2021-01-24  942  			index = MI_RATE(group, i);
a7fca4e4037f7e3 Felix Fietkau 2021-01-15  943  
a7fca4e4037f7e3 Felix Fietkau 2021-01-15  944  			/* Find max probability rate per group and global */
a7fca4e4037f7e3 Felix Fietkau 2021-01-15  945  			minstrel_ht_set_best_prob_rate(mi, &tmp_max_prob_rate,
a7fca4e4037f7e3 Felix Fietkau 2021-01-15  946  						       index);
a7fca4e4037f7e3 Felix Fietkau 2021-01-15  947  		}
a7fca4e4037f7e3 Felix Fietkau 2021-01-15  948  	}
a7fca4e4037f7e3 Felix Fietkau 2021-01-15  949  
a7fca4e4037f7e3 Felix Fietkau 2021-01-15  950  	mi->max_prob_rate = tmp_max_prob_rate;
a7fca4e4037f7e3 Felix Fietkau 2021-01-15  951  
5935839ad735837 Thomas Huehn  2014-09-09  952  	/* Try to increase robustness of max_prob_rate*/
5935839ad735837 Thomas Huehn  2014-09-09  953  	minstrel_ht_prob_rate_reduce_streams(mi);
a299c6d591f8f6a Felix Fietkau 2013-03-02  954  
eeafcb0c80c81d6 Felix Fietkau 2021-01-15  955  	/* try to sample half of all available rates during each interval */
eeafcb0c80c81d6 Felix Fietkau 2021-01-15  956  	mi->sample_count *= 4;
a299c6d591f8f6a Felix Fietkau 2013-03-02  957  
48cb39522a9d4d4 Felix Fietkau 2019-08-20  958  	if (sample)
48cb39522a9d4d4 Felix Fietkau 2019-08-20  959  		minstrel_ht_rate_sample_switch(mp, mi);
48cb39522a9d4d4 Felix Fietkau 2019-08-20  960  

---
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