mac80211: replace legacy minstrel with minstrel_ht, improve rate selection

Legacy minstrel is essentially unmaintained and was showing poor performance
Replace it with minstrel_ht and improve rate selection and sampling behavior

Signed-off-by: Felix Fietkau <nbd@nbd.name>

1 files changed, 96 insertions, 0 deletions

diff --git a/package/kernel/mac80211/patches/subsys/340-mac80211-minstrel_ht-remove-old-ewma-based-rate-aver.patch b/package/kernel/mac80211/patches/subsys/340-mac80211-minstrel_ht-remove-old-ewma-based-rate-aver.patch
new file mode 100644
index 0000000000..9b6a614aa8
--- /dev/null
+++ b/package/kernel/mac80211/patches/subsys/340-mac80211-minstrel_ht-remove-old-ewma-based-rate-aver.patch
@@ -0,0 +1,96 @@
+From: Felix Fietkau <nbd@nbd.name>
+Date: Sat, 26 Dec 2020 14:34:30 +0100
+Subject: [PATCH] mac80211: minstrel_ht: remove old ewma based rate average
+ code
+
+The new noise filter has been the default for a while now with no reported
+downside and significant improvement compared to the old code.
+
+Signed-off-by: Felix Fietkau <nbd@nbd.name>
+---
+
+--- a/net/mac80211/rc80211_minstrel_ht.c
++++ b/net/mac80211/rc80211_minstrel_ht.c
+@@ -769,17 +769,8 @@ minstrel_ht_calc_rate_stats(struct minst
+ 	if (unlikely(mrs->attempts > 0)) {
+ 		mrs->sample_skipped = 0;
+ 		cur_prob = MINSTREL_FRAC(mrs->success, mrs->attempts);
+-		if (mp->new_avg) {
+-			minstrel_filter_avg_add(&mrs->prob_avg,
+-						&mrs->prob_avg_1, cur_prob);
+-		} else if (unlikely(!mrs->att_hist)) {
+-			mrs->prob_avg = cur_prob;
+-		} else {
+-			/*update exponential weighted moving avarage */
+-			mrs->prob_avg = minstrel_ewma(mrs->prob_avg,
+-						      cur_prob,
+-						      EWMA_LEVEL);
+-		}
++		minstrel_filter_avg_add(&mrs->prob_avg,
++					&mrs->prob_avg_1, cur_prob);
+ 		mrs->att_hist += mrs->attempts;
+ 		mrs->succ_hist += mrs->success;
+ 	} else {
+@@ -913,10 +904,8 @@ minstrel_ht_update_stats(struct minstrel
+ 	/* Try to increase robustness of max_prob_rate*/
+ 	minstrel_ht_prob_rate_reduce_streams(mi);
+ 
+-	/* try to sample all available rates during each interval */
+-	mi->sample_count *= 8;
+-	if (mp->new_avg)
+-		mi->sample_count /= 2;
++	/* try to sample half of all available rates during each interval */
++	mi->sample_count *= 4;
+ 
+ 	if (sample)
+ 		minstrel_ht_rate_sample_switch(mp, mi);
+@@ -1040,7 +1029,7 @@ 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;
++	u32 update_interval = mp->update_interval;
+ 	bool last, update = false;
+ 	bool sample_status = false;
+ 	int i;
+@@ -1090,9 +1079,8 @@ 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))
++		if (mp->hw->max_rates > 1 ||
++		     mi->total_packets_cur < SAMPLE_SWITCH_THR)
+ 			update_interval /= 2;
+ 		break;
+ 
+@@ -1832,8 +1820,7 @@ minstrel_ht_alloc(struct ieee80211_hw *h
+ 		mp->has_mrr = true;
+ 
+ 	mp->hw = hw;
+-	mp->update_interval = HZ / 10;
+-	mp->new_avg = true;
++	mp->update_interval = HZ / 20;
+ 
+ 	minstrel_ht_init_cck_rates(mp);
+ 	for (i = 0; i < ARRAY_SIZE(mp->hw->wiphy->bands); i++)
+@@ -1853,8 +1840,6 @@ static void minstrel_ht_add_debugfs(stru
+ 			   &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
+ 
+--- a/net/mac80211/rc80211_minstrel_ht.h
++++ b/net/mac80211/rc80211_minstrel_ht.h
+@@ -60,7 +60,6 @@
+ struct minstrel_priv {
+ 	struct ieee80211_hw *hw;
+ 	bool has_mrr;
+-	bool new_avg;
+ 	u32 sample_switch;
+ 	unsigned int cw_min;
+ 	unsigned int cw_max;