mac80211: add an improved moving average algorithm to minstrel

Improves rate control responsiveness and performance

Signed-off-by: Felix Fietkau <nbd@nbd.name>
[reworked to apply on 4.19.79 mac80211 + renumbered + refreshed]
Signed-off-by: Koen Vandeputte <koen.vandeputte@ncentric.com>

3 files changed, 733 insertions, 0 deletions

diff --git a/package/kernel/mac80211/patches/subsys/362-mac80211-minstrel-remove-divisions-in-tx-status-path.patch b/package/kernel/mac80211/patches/subsys/362-mac80211-minstrel-remove-divisions-in-tx-status-path.patch
new file mode 100644
index 0000000000..d38d33b41e
--- /dev/null
+++ b/package/kernel/mac80211/patches/subsys/362-mac80211-minstrel-remove-divisions-in-tx-status-path.patch
@@ -0,0 +1,61 @@
+From: Felix Fietkau <nbd@nbd.name>
+Date: Sat, 28 Sep 2019 15:44:06 +0200
+Subject: [PATCH] mac80211: minstrel: remove divisions in tx status path
+
+Use a slightly different threshold for downgrading spatial streams to
+make it easier to calculate without divisions.
+Slightly reduces CPU overhead.
+
+Signed-off-by: Felix Fietkau <nbd@nbd.name>
+---
+
+--- a/net/mac80211/rc80211_minstrel.c
++++ b/net/mac80211/rc80211_minstrel.c
+@@ -295,8 +295,7 @@ minstrel_tx_status(void *priv, struct ie
+ 	if (mi->sample_deferred > 0)
+ 		mi->sample_deferred--;
+ 
+-	if (time_after(jiffies, mi->last_stats_update +
+-				(mp->update_interval * HZ) / 1000))
++	if (time_after(jiffies, mi->last_stats_update + mp->update_interval))
+ 		minstrel_update_stats(mp, mi);
+ }
+ 
+--- a/net/mac80211/rc80211_minstrel_ht.c
++++ b/net/mac80211/rc80211_minstrel_ht.c
+@@ -937,23 +937,21 @@ minstrel_ht_tx_status(void *priv, struct
+ 		 */
+ 		rate = minstrel_get_ratestats(mi, mi->max_tp_rate[0]);
+ 		if (rate->attempts > 30 &&
+-		    MINSTREL_FRAC(rate->success, rate->attempts) <
+-		    MINSTREL_FRAC(20, 100)) {
++		    rate->success < rate->attempts / 4) {
+ 			minstrel_downgrade_rate(mi, &mi->max_tp_rate[0], true);
+ 			update = true;
+ 		}
+ 
+ 		rate2 = minstrel_get_ratestats(mi, mi->max_tp_rate[1]);
+ 		if (rate2->attempts > 30 &&
+-		    MINSTREL_FRAC(rate2->success, rate2->attempts) <
+-		    MINSTREL_FRAC(20, 100)) {
++		    rate2->success < rate2->attempts / 4) {
+ 			minstrel_downgrade_rate(mi, &mi->max_tp_rate[1], false);
+ 			update = true;
+ 		}
+ 	}
+ 
+ 	if (time_after(jiffies, mi->last_stats_update +
+-				(mp->update_interval / 2 * HZ) / 1000)) {
++				mp->update_interval / 2)) {
+ 		update = true;
+ 		minstrel_ht_update_stats(mp, mi, true);
+ 	}
+@@ -1640,7 +1638,7 @@ minstrel_ht_alloc(struct ieee80211_hw *h
+ 		mp->has_mrr = true;
+ 
+ 	mp->hw = hw;
+-	mp->update_interval = 100;
++	mp->update_interval = HZ / 10;
+ 
+ #ifdef CPTCFG_MAC80211_DEBUGFS
+ 	mp->fixed_rate_idx = (u32) -1;
diff --git a/package/kernel/mac80211/patches/subsys/363-mac80211-minstrel_ht-replace-rate-stats-ewma-with-a-.patch b/package/kernel/mac80211/patches/subsys/363-mac80211-minstrel_ht-replace-rate-stats-ewma-with-a-.patch
new file mode 100644
index 0000000000..5e2a017865
--- /dev/null
+++ b/package/kernel/mac80211/patches/subsys/363-mac80211-minstrel_ht-replace-rate-stats-ewma-with-a-.patch
@@ -0,0 +1,235 @@
+From: Felix Fietkau <nbd@nbd.name>
+Date: Sat, 28 Sep 2019 15:46:06 +0200
+Subject: [PATCH] mac80211: minstrel_ht: replace rate stats ewma with a
+ better moving average
+
+Rate success probability usually fluctuates a lot under normal conditions.
+With a simple EWMA, noise and fluctuation can be reduced by increasing the
+window length, but that comes at the cost of introducing lag on sudden
+changes.
+
+This change replaces the EWMA implementation with a moving average that's
+designed to significantly reduce lag while keeping a bigger window size
+by being better at filtering out noise.
+
+It is only slightly more expensive than the simple EWMA and still avoids
+divisions in its calculation.
+
+The algorithm is adapted from an implementation intended for a completely
+different field (stock market trading), where the tradeoff of lag vs
+noise filtering is equally important.
+
+The algorithm works in the same way as the "smoothing filter" from
+http://www.stockspotter.com/files/PredictiveIndicators.pdf adapted for
+fixed-point math with some constants, using only addition, bit shifts
+and multiplication
+
+To better make use of the filtering and bigger window size, the update
+interval is cut in half.
+
+For testing, the algorithm can be reverted to the older one via debugfs
+
+Signed-off-by: Felix Fietkau <nbd@nbd.name>
+---
+
+--- a/net/mac80211/rc80211_minstrel.c
++++ b/net/mac80211/rc80211_minstrel.c
+@@ -157,14 +157,18 @@ minstrel_update_rates(struct minstrel_pr
+ * Recalculate statistics and counters of a given rate
+ */
+ void
+-minstrel_calc_rate_stats(struct minstrel_rate_stats *mrs)
++minstrel_calc_rate_stats(struct minstrel_priv *mp,
++			 struct minstrel_rate_stats *mrs)
+ {
+ 	unsigned int cur_prob;
+ 
+ 	if (unlikely(mrs->attempts > 0)) {
+ 		mrs->sample_skipped = 0;
+ 		cur_prob = MINSTREL_FRAC(mrs->success, mrs->attempts);
+-		if (unlikely(!mrs->att_hist)) {
++		if (mp->new_avg) {
++			mrs->prob_ewma = minstrel_filter_avg_add(&mrs->avg,
++								 cur_prob);
++		} else if (unlikely(!mrs->att_hist)) {
+ 			mrs->prob_ewma = cur_prob;
+ 		} else {
+ 			/* update exponential weighted moving variance */
+@@ -206,7 +210,7 @@ minstrel_update_stats(struct minstrel_pr
+ 		struct minstrel_rate_stats *tmp_mrs = &mi->r[tmp_prob_rate].stats;
+ 
+ 		/* Update statistics of success probability per rate */
+-		minstrel_calc_rate_stats(mrs);
++		minstrel_calc_rate_stats(mp, mrs);
+ 
+ 		/* Sample less often below the 10% chance of success.
+ 		 * Sample less often above the 95% chance of success. */
+@@ -295,7 +299,8 @@ minstrel_tx_status(void *priv, struct ie
+ 	if (mi->sample_deferred > 0)
+ 		mi->sample_deferred--;
+ 
+-	if (time_after(jiffies, mi->last_stats_update + mp->update_interval))
++	if (time_after(jiffies, mi->last_stats_update +
++				mp->update_interval / (mp->new_avg ? 2 : 1)))
+ 		minstrel_update_stats(mp, mi);
+ }
+ 
+--- a/net/mac80211/rc80211_minstrel.h
++++ b/net/mac80211/rc80211_minstrel.h
+@@ -22,6 +22,21 @@
+ #define MAX_THR_RATES 4
+ 
+ /*
++ * Coefficients for moving average with noise filter (period=16),
++ * scaled by 10 bits
++ *
++ * a1 = exp(-pi * sqrt(2) / period)
++ * coeff2 = 2 * a1 * cos(sqrt(2) * 2 * pi / period)
++ * coeff3 = -sqr(a1)
++ * coeff1 = 1 - coeff2 - coeff3
++ */
++#define MINSTREL_AVG_COEFF1		(MINSTREL_FRAC(1, 1) - \
++					 MINSTREL_AVG_COEFF2 - \
++					 MINSTREL_AVG_COEFF3)
++#define MINSTREL_AVG_COEFF2		0x00001499
++#define MINSTREL_AVG_COEFF3		-0x0000092e
++
++/*
+  * Perform EWMA (Exponentially Weighted Moving Average) calculation
+  */
+ static inline int
+@@ -48,6 +63,41 @@ minstrel_ewmv(int old_ewmv, int cur_prob
+ 	return weight * (old_ewmv + MINSTREL_TRUNC(diff * incr)) / EWMA_DIV;
+ }
+ 
++struct minstrel_avg_ctx {
++	s32 prev[2];
++};
++
++static inline int minstrel_filter_avg_add(struct minstrel_avg_ctx *ctx, s32 in)
++{
++	s32 out_1 = ctx->prev[0];
++	s32 out_2 = ctx->prev[1];
++	s32 val;
++
++	if (!in)
++		in += 1;
++
++	if (!out_1) {
++		val = out_1 = in;
++		goto out;
++	}
++
++	val = MINSTREL_AVG_COEFF1 * in;
++	val += MINSTREL_AVG_COEFF2 * out_1;
++	val += MINSTREL_AVG_COEFF3 * out_2;
++	val >>= MINSTREL_SCALE;
++
++	if (val > 1 << MINSTREL_SCALE)
++		val = 1 << MINSTREL_SCALE;
++	if (val < 0)
++		val = 1;
++
++out:
++	ctx->prev[1] = out_1;
++	ctx->prev[0] = val;
++
++	return val;
++}
++
+ struct minstrel_rate_stats {
+ 	/* current / last sampling period attempts/success counters */
+ 	u16 attempts, last_attempts;
+@@ -56,6 +106,8 @@ struct minstrel_rate_stats {
+ 	/* total attempts/success counters */
+ 	u32 att_hist, succ_hist;
+ 
++	struct minstrel_avg_ctx avg;
++
+ 	/* statistis of packet delivery probability
+ 	 *  prob_ewma - exponential weighted moving average of prob
+ 	 *  prob_ewmsd - exp. weighted moving standard deviation of prob */
+@@ -114,6 +166,7 @@ struct minstrel_sta_info {
+ struct minstrel_priv {
+ 	struct ieee80211_hw *hw;
+ 	bool has_mrr;
++	bool new_avg;
+ 	u32 sample_switch;
+ 	unsigned int cw_min;
+ 	unsigned int cw_max;
+@@ -153,7 +206,8 @@ extern const struct rate_control_ops mac
+ void minstrel_add_sta_debugfs(void *priv, void *priv_sta, struct dentry *dir);
+ 
+ /* Recalculate success probabilities and counters for a given rate using EWMA */
+-void minstrel_calc_rate_stats(struct minstrel_rate_stats *mrs);
++void minstrel_calc_rate_stats(struct minstrel_priv *mp,
++			      struct minstrel_rate_stats *mrs);
+ int minstrel_get_tp_avg(struct minstrel_rate *mr, int prob_ewma);
+ 
+ /* debugfs */
+--- a/net/mac80211/rc80211_minstrel_ht.c
++++ b/net/mac80211/rc80211_minstrel_ht.c
+@@ -704,7 +704,7 @@ minstrel_ht_update_stats(struct minstrel
+ 
+ 			mrs = &mg->rates[i];
+ 			mrs->retry_updated = false;
+-			minstrel_calc_rate_stats(mrs);
++			minstrel_calc_rate_stats(mp, mrs);
+ 			cur_prob = mrs->prob_ewma;
+ 
+ 			if (minstrel_ht_get_tp_avg(mi, group, i, cur_prob) == 0)
+@@ -740,6 +740,8 @@ minstrel_ht_update_stats(struct minstrel
+ 
+ 	/* try to sample all available rates during each interval */
+ 	mi->sample_count *= 8;
++	if (mp->new_avg)
++		mi->sample_count /= 2;
+ 
+ 	if (sample)
+ 		minstrel_ht_rate_sample_switch(mp, mi);
+@@ -856,6 +858,7 @@ minstrel_ht_tx_status(void *priv, struct
+ 	struct ieee80211_tx_rate *ar = info->status.rates;
+ 	struct minstrel_rate_stats *rate, *rate2, *rate_sample = NULL;
+ 	struct minstrel_priv *mp = priv;
++	u32 update_interval = mp->update_interval / 2;
+ 	bool last, update = false;
+ 	bool sample_status = false;
+ 	int i;
+@@ -910,6 +913,10 @@ minstrel_ht_tx_status(void *priv, struct
+ 
+ 	switch (mi->sample_mode) {
+ 	case MINSTREL_SAMPLE_IDLE:
++		if (mp->new_avg &&
++		    (mp->hw->max_rates > 1 ||
++		     mi->total_packets_cur < SAMPLE_SWITCH_THR))
++			update_interval /= 2;
+ 		break;
+ 
+ 	case MINSTREL_SAMPLE_ACTIVE:
+@@ -950,8 +957,7 @@ minstrel_ht_tx_status(void *priv, struct
+ 		}
+ 	}
+ 
+-	if (time_after(jiffies, mi->last_stats_update +
+-				mp->update_interval / 2)) {
++	if (time_after(jiffies, mi->last_stats_update + update_interval)) {
+ 		update = true;
+ 		minstrel_ht_update_stats(mp, mi, true);
+ 	}
+@@ -1639,6 +1645,7 @@ minstrel_ht_alloc(struct ieee80211_hw *h
+ 
+ 	mp->hw = hw;
+ 	mp->update_interval = HZ / 10;
++	mp->new_avg = true;
+ 
+ #ifdef CPTCFG_MAC80211_DEBUGFS
+ 	mp->fixed_rate_idx = (u32) -1;
+@@ -1646,6 +1653,8 @@ minstrel_ht_alloc(struct ieee80211_hw *h
+ 			   &mp->fixed_rate_idx);
+ 	debugfs_create_u32("sample_switch", S_IRUGO | S_IWUSR, debugfsdir,
+ 			   &mp->sample_switch);
++	debugfs_create_bool("new_avg", S_IRUGO | S_IWUSR, debugfsdir,
++			   &mp->new_avg);
+ #endif
+ 
+ 	minstrel_ht_init_cck_rates(mp);
diff --git a/package/kernel/mac80211/patches/subsys/364-mac80211-minstrel_ht-rename-prob_ewma-to-prob_avg-us.patch b/package/kernel/mac80211/patches/subsys/364-mac80211-minstrel_ht-rename-prob_ewma-to-prob_avg-us.patch
new file mode 100644
index 0000000000..c919643505
--- /dev/null
+++ b/package/kernel/mac80211/patches/subsys/364-mac80211-minstrel_ht-rename-prob_ewma-to-prob_avg-us.patch
@@ -0,0 +1,437 @@
+From: Felix Fietkau <nbd@nbd.name>
+Date: Tue, 8 Oct 2019 18:54:46 +0200
+Subject: [PATCH] mac80211: minstrel_ht: rename prob_ewma to prob_avg, use it
+ for the new average
+
+Reduces per-rate data structure size
+
+Signed-off-by: Felix Fietkau <nbd@nbd.name>
+---
+
+--- a/net/mac80211/rc80211_minstrel.c
++++ b/net/mac80211/rc80211_minstrel.c
+@@ -70,7 +70,7 @@ rix_to_ndx(struct minstrel_sta_info *mi,
+ }
+ 
+ /* return current EMWA throughput */
+-int minstrel_get_tp_avg(struct minstrel_rate *mr, int prob_ewma)
++int minstrel_get_tp_avg(struct minstrel_rate *mr, int prob_avg)
+ {
+ 	int usecs;
+ 
+@@ -79,13 +79,13 @@ int minstrel_get_tp_avg(struct minstrel_
+ 		usecs = 1000000;
+ 
+ 	/* reset thr. below 10% success */
+-	if (mr->stats.prob_ewma < MINSTREL_FRAC(10, 100))
++	if (mr->stats.prob_avg < MINSTREL_FRAC(10, 100))
+ 		return 0;
+ 
+-	if (prob_ewma > MINSTREL_FRAC(90, 100))
++	if (prob_avg > MINSTREL_FRAC(90, 100))
+ 		return MINSTREL_TRUNC(100000 * (MINSTREL_FRAC(90, 100) / usecs));
+ 	else
+-		return MINSTREL_TRUNC(100000 * (prob_ewma / usecs));
++		return MINSTREL_TRUNC(100000 * (prob_avg / usecs));
+ }
+ 
+ /* find & sort topmost throughput rates */
+@@ -98,8 +98,8 @@ minstrel_sort_best_tp_rates(struct minst
+ 
+ 	for (j = MAX_THR_RATES; j > 0; --j) {
+ 		tmp_mrs = &mi->r[tp_list[j - 1]].stats;
+-		if (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))
++		if (minstrel_get_tp_avg(&mi->r[i], cur_mrs->prob_avg) <=
++		    minstrel_get_tp_avg(&mi->r[tp_list[j - 1]], tmp_mrs->prob_avg))
+ 			break;
+ 	}
+ 
+@@ -166,21 +166,21 @@ minstrel_calc_rate_stats(struct minstrel
+ 		mrs->sample_skipped = 0;
+ 		cur_prob = MINSTREL_FRAC(mrs->success, mrs->attempts);
+ 		if (mp->new_avg) {
+-			mrs->prob_ewma = minstrel_filter_avg_add(&mrs->avg,
+-								 cur_prob);
++			minstrel_filter_avg_add(&mrs->prob_avg,
++						&mrs->prob_avg_1, cur_prob);
+ 		} else if (unlikely(!mrs->att_hist)) {
+-			mrs->prob_ewma = cur_prob;
++			mrs->prob_avg = cur_prob;
+ 		} else {
+ 			/* update exponential weighted moving variance */
+ 			mrs->prob_ewmv = minstrel_ewmv(mrs->prob_ewmv,
+ 							cur_prob,
+-							mrs->prob_ewma,
++							mrs->prob_avg,
+ 							EWMA_LEVEL);
+ 
+ 			/*update exponential weighted moving avarage */
+-			mrs->prob_ewma = minstrel_ewma(mrs->prob_ewma,
+-						       cur_prob,
+-						       EWMA_LEVEL);
++			mrs->prob_avg = minstrel_ewma(mrs->prob_avg,
++							cur_prob,
++							EWMA_LEVEL);
+ 		}
+ 		mrs->att_hist += mrs->attempts;
+ 		mrs->succ_hist += mrs->success;
+@@ -214,8 +214,8 @@ minstrel_update_stats(struct minstrel_pr
+ 
+ 		/* Sample less often below the 10% chance of success.
+ 		 * Sample less often above the 95% chance of success. */
+-		if (mrs->prob_ewma > MINSTREL_FRAC(95, 100) ||
+-		    mrs->prob_ewma < MINSTREL_FRAC(10, 100)) {
++		if (mrs->prob_avg > MINSTREL_FRAC(95, 100) ||
++		    mrs->prob_avg < MINSTREL_FRAC(10, 100)) {
+ 			mr->adjusted_retry_count = mrs->retry_count >> 1;
+ 			if (mr->adjusted_retry_count > 2)
+ 				mr->adjusted_retry_count = 2;
+@@ -235,14 +235,14 @@ minstrel_update_stats(struct minstrel_pr
+ 		 * choose the maximum throughput rate as max_prob_rate
+ 		 * (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, mrs->prob_ewma);
++		if (mrs->prob_avg >= MINSTREL_FRAC(95, 100)) {
++			tmp_cur_tp = minstrel_get_tp_avg(mr, mrs->prob_avg);
+ 			tmp_prob_tp = minstrel_get_tp_avg(&mi->r[tmp_prob_rate],
+-							  tmp_mrs->prob_ewma);
++							  tmp_mrs->prob_avg);
+ 			if (tmp_cur_tp >= tmp_prob_tp)
+ 				tmp_prob_rate = i;
+ 		} else {
+-			if (mrs->prob_ewma >= tmp_mrs->prob_ewma)
++			if (mrs->prob_avg >= tmp_mrs->prob_avg)
+ 				tmp_prob_rate = i;
+ 		}
+ 	}
+@@ -436,7 +436,7 @@ minstrel_get_rate(void *priv, struct iee
+ 	 * has a probability of >95%, we shouldn't be attempting
+ 	 * to use it, as this only wastes precious airtime */
+ 	if (!mrr_capable &&
+-	   (mi->r[ndx].stats.prob_ewma > MINSTREL_FRAC(95, 100)))
++	   (mi->r[ndx].stats.prob_avg > MINSTREL_FRAC(95, 100)))
+ 		return;
+ 
+ 	mi->prev_sample = true;
+@@ -587,7 +587,7 @@ static u32 minstrel_get_expected_through
+ 	 * computing cur_tp
+ 	 */
+ 	tmp_mrs = &mi->r[idx].stats;
+-	tmp_cur_tp = minstrel_get_tp_avg(&mi->r[idx], tmp_mrs->prob_ewma) * 10;
++	tmp_cur_tp = minstrel_get_tp_avg(&mi->r[idx], tmp_mrs->prob_avg) * 10;
+ 	tmp_cur_tp = tmp_cur_tp * 1200 * 8 / 1024;
+ 
+ 	return tmp_cur_tp;
+--- a/net/mac80211/rc80211_minstrel.h
++++ b/net/mac80211/rc80211_minstrel.h
+@@ -63,14 +63,10 @@ minstrel_ewmv(int old_ewmv, int cur_prob
+ 	return weight * (old_ewmv + MINSTREL_TRUNC(diff * incr)) / EWMA_DIV;
+ }
+ 
+-struct minstrel_avg_ctx {
+-	s32 prev[2];
+-};
+-
+-static inline int minstrel_filter_avg_add(struct minstrel_avg_ctx *ctx, s32 in)
++static inline int minstrel_filter_avg_add(u16 *prev_1, u16 *prev_2, s32 in)
+ {
+-	s32 out_1 = ctx->prev[0];
+-	s32 out_2 = ctx->prev[1];
++	s32 out_1 = *prev_1;
++	s32 out_2 = *prev_2;
+ 	s32 val;
+ 
+ 	if (!in)
+@@ -92,8 +88,8 @@ static inline int minstrel_filter_avg_ad
+ 		val = 1;
+ 
+ out:
+-	ctx->prev[1] = out_1;
+-	ctx->prev[0] = val;
++	*prev_2 = out_1;
++	*prev_1 = val;
+ 
+ 	return val;
+ }
+@@ -106,14 +102,15 @@ struct minstrel_rate_stats {
+ 	/* total attempts/success counters */
+ 	u32 att_hist, succ_hist;
+ 
+-	struct minstrel_avg_ctx avg;
+-
+ 	/* statistis of packet delivery probability
+ 	 *  prob_ewma - exponential weighted moving average of prob
+ 	 *  prob_ewmsd - exp. weighted moving standard deviation of prob */
+-	u16 prob_ewma;
+ 	u16 prob_ewmv;
+ 
++	/* prob_avg - moving average of prob */
++	u16 prob_avg;
++	u16 prob_avg_1;
++
+ 	/* maximum retry counts */
+ 	u8 retry_count;
+ 	u8 retry_count_rtscts;
+@@ -208,7 +205,7 @@ void minstrel_add_sta_debugfs(void *priv
+ /* Recalculate success probabilities and counters for a given rate using EWMA */
+ void minstrel_calc_rate_stats(struct minstrel_priv *mp,
+ 			      struct minstrel_rate_stats *mrs);
+-int minstrel_get_tp_avg(struct minstrel_rate *mr, int prob_ewma);
++int minstrel_get_tp_avg(struct minstrel_rate *mr, int prob_avg);
+ 
+ /* debugfs */
+ int minstrel_stats_open(struct inode *inode, struct file *file);
+--- a/net/mac80211/rc80211_minstrel_debugfs.c
++++ b/net/mac80211/rc80211_minstrel_debugfs.c
+@@ -91,8 +91,9 @@ minstrel_stats_open(struct inode *inode,
+ 		p += sprintf(p, "%6u ", mr->perfect_tx_time);
+ 
+ 		tp_max = minstrel_get_tp_avg(mr, MINSTREL_FRAC(100,100));
+-		tp_avg = minstrel_get_tp_avg(mr, mrs->prob_ewma);
+-		eprob = MINSTREL_TRUNC(mrs->prob_ewma * 1000);
++		tp_avg = minstrel_get_tp_avg(mr, mrs->prob_avg);
++		eprob = MINSTREL_TRUNC(mrs->prob_avg * 1000);
++
+ 		prob_ewmsd = minstrel_get_ewmsd10(mrs);
+ 
+ 		p += sprintf(p, "%4u.%1u    %4u.%1u     %3u.%1u    %3u.%1u"
+@@ -151,8 +152,8 @@ minstrel_stats_csv_open(struct inode *in
+ 		p += sprintf(p, "%u,",mr->perfect_tx_time);
+ 
+ 		tp_max = minstrel_get_tp_avg(mr, MINSTREL_FRAC(100,100));
+-		tp_avg = minstrel_get_tp_avg(mr, mrs->prob_ewma);
+-		eprob = MINSTREL_TRUNC(mrs->prob_ewma * 1000);
++		tp_avg = minstrel_get_tp_avg(mr, mrs->prob_avg);
++		eprob = MINSTREL_TRUNC(mrs->prob_avg * 1000);
+ 		prob_ewmsd = minstrel_get_ewmsd10(mrs);
+ 
+ 		p += sprintf(p, "%u.%u,%u.%u,%u.%u,%u.%u,%u,%u,%u,"
+--- a/net/mac80211/rc80211_minstrel_ht.c
++++ b/net/mac80211/rc80211_minstrel_ht.c
+@@ -313,12 +313,12 @@ minstrel_ht_avg_ampdu_len(struct minstre
+  */
+ int
+ minstrel_ht_get_tp_avg(struct minstrel_ht_sta *mi, int group, int rate,
+-		       int prob_ewma)
++		       int prob_avg)
+ {
+ 	unsigned int nsecs = 0;
+ 
+ 	/* do not account throughput if sucess prob is below 10% */
+-	if (prob_ewma < MINSTREL_FRAC(10, 100))
++	if (prob_avg < MINSTREL_FRAC(10, 100))
+ 		return 0;
+ 
+ 	if (group != MINSTREL_CCK_GROUP)
+@@ -332,11 +332,11 @@ minstrel_ht_get_tp_avg(struct minstrel_h
+ 	 * account for collision related packet error rate fluctuation
+ 	 * (prob is scaled - see MINSTREL_FRAC above)
+ 	 */
+-	if (prob_ewma > MINSTREL_FRAC(90, 100))
++	if (prob_avg > MINSTREL_FRAC(90, 100))
+ 		return MINSTREL_TRUNC(100000 * ((MINSTREL_FRAC(90, 100) * 1000)
+ 								      / nsecs));
+ 	else
+-		return MINSTREL_TRUNC(100000 * ((prob_ewma * 1000) / nsecs));
++		return MINSTREL_TRUNC(100000 * ((prob_avg * 1000) / nsecs));
+ }
+ 
+ /*
+@@ -356,13 +356,13 @@ minstrel_ht_sort_best_tp_rates(struct mi
+ 
+ 	cur_group = index / MCS_GROUP_RATES;
+ 	cur_idx = index  % MCS_GROUP_RATES;
+-	cur_prob = mi->groups[cur_group].rates[cur_idx].prob_ewma;
++	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_prob = mi->groups[tmp_group].rates[tmp_idx].prob_ewma;
++		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 (cur_tp_avg < tmp_tp_avg ||
+@@ -399,7 +399,7 @@ minstrel_ht_set_best_prob_rate(struct mi
+ 
+ 	tmp_group = mi->max_prob_rate / MCS_GROUP_RATES;
+ 	tmp_idx = mi->max_prob_rate % MCS_GROUP_RATES;
+-	tmp_prob = mi->groups[tmp_group].rates[tmp_idx].prob_ewma;
++	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
+@@ -411,11 +411,11 @@ minstrel_ht_set_best_prob_rate(struct mi
+ 
+ 	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_prob = mi->groups[max_gpr_group].rates[max_gpr_idx].prob_avg;
+ 
+-	if (mrs->prob_ewma > MINSTREL_FRAC(75, 100)) {
++	if (mrs->prob_avg > MINSTREL_FRAC(75, 100)) {
+ 		cur_tp_avg = minstrel_ht_get_tp_avg(mi, cur_group, cur_idx,
+-						    mrs->prob_ewma);
++						    mrs->prob_avg);
+ 		if (cur_tp_avg > tmp_tp_avg)
+ 			mi->max_prob_rate = index;
+ 
+@@ -425,9 +425,9 @@ minstrel_ht_set_best_prob_rate(struct mi
+ 		if (cur_tp_avg > max_gpr_tp_avg)
+ 			mg->max_group_prob_rate = index;
+ 	} else {
+-		if (mrs->prob_ewma > tmp_prob)
++		if (mrs->prob_avg > tmp_prob)
+ 			mi->max_prob_rate = index;
+-		if (mrs->prob_ewma > max_gpr_prob)
++		if (mrs->prob_avg > max_gpr_prob)
+ 			mg->max_group_prob_rate = index;
+ 	}
+ }
+@@ -449,12 +449,12 @@ minstrel_ht_assign_best_tp_rates(struct
+ 
+ 	tmp_group = tmp_cck_tp_rate[0] / MCS_GROUP_RATES;
+ 	tmp_idx = tmp_cck_tp_rate[0] % MCS_GROUP_RATES;
+-	tmp_prob = mi->groups[tmp_group].rates[tmp_idx].prob_ewma;
++	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_prob = mi->groups[tmp_group].rates[tmp_idx].prob_ewma;
++	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);
+ 
+ 	if (tmp_cck_tp_rate && tmp_cck_tp > tmp_mcs_tp) {
+@@ -485,7 +485,7 @@ minstrel_ht_prob_rate_reduce_streams(str
+ 			continue;
+ 
+ 		tmp_idx = mg->max_group_prob_rate % MCS_GROUP_RATES;
+-		tmp_prob = mi->groups[group].rates[tmp_idx].prob_ewma;
++		tmp_prob = mi->groups[group].rates[tmp_idx].prob_avg;
+ 
+ 		if (tmp_tp < minstrel_ht_get_tp_avg(mi, group, tmp_idx, tmp_prob) &&
+ 		   (minstrel_mcs_groups[group].streams < tmp_max_streams)) {
+@@ -590,7 +590,7 @@ minstrel_ht_rate_sample_switch(struct mi
+ 	 * 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_ewma > MINSTREL_FRAC(75, 100);
++	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);
+@@ -705,7 +705,7 @@ minstrel_ht_update_stats(struct minstrel
+ 			mrs = &mg->rates[i];
+ 			mrs->retry_updated = false;
+ 			minstrel_calc_rate_stats(mp, mrs);
+-			cur_prob = mrs->prob_ewma;
++			cur_prob = mrs->prob_avg;
+ 
+ 			if (minstrel_ht_get_tp_avg(mi, group, i, cur_prob) == 0)
+ 				continue;
+@@ -979,7 +979,7 @@ minstrel_calc_retransmit(struct minstrel
+ 	unsigned int overhead = 0, overhead_rtscts = 0;
+ 
+ 	mrs = minstrel_get_ratestats(mi, index);
+-	if (mrs->prob_ewma < MINSTREL_FRAC(1, 10)) {
++	if (mrs->prob_avg < MINSTREL_FRAC(1, 10)) {
+ 		mrs->retry_count = 1;
+ 		mrs->retry_count_rtscts = 1;
+ 		return;
+@@ -1036,7 +1036,7 @@ minstrel_ht_set_rate(struct minstrel_pri
+ 	if (!mrs->retry_updated)
+ 		minstrel_calc_retransmit(mp, mi, index);
+ 
+-	if (mrs->prob_ewma < MINSTREL_FRAC(20, 100) || !mrs->retry_count) {
++	if (mrs->prob_avg < MINSTREL_FRAC(20, 100) || !mrs->retry_count) {
+ 		ratetbl->rate[offset].count = 2;
+ 		ratetbl->rate[offset].count_rts = 2;
+ 		ratetbl->rate[offset].count_cts = 2;
+@@ -1070,11 +1070,11 @@ minstrel_ht_set_rate(struct minstrel_pri
+ }
+ 
+ static inline int
+-minstrel_ht_get_prob_ewma(struct minstrel_ht_sta *mi, int rate)
++minstrel_ht_get_prob_avg(struct minstrel_ht_sta *mi, int rate)
+ {
+ 	int group = rate / MCS_GROUP_RATES;
+ 	rate %= MCS_GROUP_RATES;
+-	return mi->groups[group].rates[rate].prob_ewma;
++	return mi->groups[group].rates[rate].prob_avg;
+ }
+ 
+ static int
+@@ -1086,7 +1086,7 @@ minstrel_ht_get_max_amsdu_len(struct min
+ 	unsigned int duration;
+ 
+ 	/* Disable A-MSDU if max_prob_rate is bad */
+-	if (mi->groups[group].rates[rate].prob_ewma < MINSTREL_FRAC(50, 100))
++	if (mi->groups[group].rates[rate].prob_avg < MINSTREL_FRAC(50, 100))
+ 		return 1;
+ 
+ 	duration = g->duration[rate];
+@@ -1109,7 +1109,7 @@ minstrel_ht_get_max_amsdu_len(struct min
+ 	 * data packet size
+ 	 */
+ 	if (duration > MCS_DURATION(1, 0, 260) ||
+-	    (minstrel_ht_get_prob_ewma(mi, mi->max_tp_rate[0]) <
++	    (minstrel_ht_get_prob_avg(mi, mi->max_tp_rate[0]) <
+ 	     MINSTREL_FRAC(75, 100)))
+ 		return 3200;
+ 
+@@ -1216,7 +1216,7 @@ minstrel_get_sample_rate(struct minstrel
+ 	 * rate, to avoid wasting airtime.
+ 	 */
+ 	sample_dur = minstrel_get_duration(sample_idx);
+-	if (mrs->prob_ewma > MINSTREL_FRAC(95, 100) ||
++	if (mrs->prob_avg > MINSTREL_FRAC(95, 100) ||
+ 	    minstrel_get_duration(mi->max_prob_rate) * 3 < sample_dur)
+ 		return -1;
+ 
+@@ -1679,7 +1679,7 @@ static u32 minstrel_ht_get_expected_thro
+ 
+ 	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;
++	prob = mi->groups[i].rates[j].prob_avg;
+ 
+ 	/* convert tp_avg from pkt per second in kbps */
+ 	tp_avg = minstrel_ht_get_tp_avg(mi, i, j, prob) * 10;
+--- a/net/mac80211/rc80211_minstrel_ht.h
++++ b/net/mac80211/rc80211_minstrel_ht.h
+@@ -122,6 +122,6 @@ struct minstrel_ht_sta_priv {
+ 
+ void minstrel_ht_add_sta_debugfs(void *priv, void *priv_sta, struct dentry *dir);
+ int minstrel_ht_get_tp_avg(struct minstrel_ht_sta *mi, int group, int rate,
+-			   int prob_ewma);
++			   int prob_avg);
+ 
+ #endif
+--- a/net/mac80211/rc80211_minstrel_ht_debugfs.c
++++ b/net/mac80211/rc80211_minstrel_ht_debugfs.c
+@@ -102,8 +102,8 @@ minstrel_ht_stats_dump(struct minstrel_h
+ 		p += sprintf(p, "%6u  ", tx_time);
+ 
+ 		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);
+-		eprob = MINSTREL_TRUNC(mrs->prob_ewma * 1000);
++		tp_avg = minstrel_ht_get_tp_avg(mi, i, j, mrs->prob_avg);
++		eprob = MINSTREL_TRUNC(mrs->prob_avg * 1000);
+ 		prob_ewmsd = minstrel_get_ewmsd10(mrs);
+ 
+ 		p += sprintf(p, "%4u.%1u    %4u.%1u     %3u.%1u    %3u.%1u"
+@@ -250,8 +250,8 @@ minstrel_ht_stats_csv_dump(struct minstr
+ 		p += sprintf(p, "%u,", tx_time);
+ 
+ 		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);
+-		eprob = MINSTREL_TRUNC(mrs->prob_ewma * 1000);
++		tp_avg = minstrel_ht_get_tp_avg(mi, i, j, mrs->prob_avg);
++		eprob = MINSTREL_TRUNC(mrs->prob_avg * 1000);
+ 		prob_ewmsd = minstrel_get_ewmsd10(mrs);
+ 
+ 		p += sprintf(p, "%u.%u,%u.%u,%u.%u,%u.%u,%u,%u,"